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  • 51.
    Clément, Gaël
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för fysiologi och utvecklingsbiologi, Evolutionär organismbiologi.
    Ahlberg, Per E
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    The endocranial anatomy of the early sarcopterygian Powichthys from Spitsbergen, based on CT scanning2010Ingår i: Morphology, Phylogeny and Paleobiogeography of Fossil Fishes: honoring Meemann Chang / [ed] David K. Elliott, John G. Maisey, Xiaobo Yu, Desui Miao, München: Dr. Friedrich Pfeil , 2010, s. 363-377Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 52.
    Dupret, Vincent
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab. Australian Natl Univ, Dept Appl Math, Res Sch Phys & Engn, Canberra, ACT, Australia..
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab. European Synchrotron Radiat Facil, Grenoble, France..
    Goujet, Daniel
    UPMC Paris 6, CNRS, MNHN, CR2P UMR 7207,Sorbonne Univ,Museum Natl Hist Nat, Paris, France..
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    The internal cranial anatomy of Romundina stellina Orvig, 1975 (Vertebrata, Placodermi, Acanthothoraci) and the origin of jawed vertebrates: Anatomical atlas of a primitive gnathostome2017Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, nr 2, artikel-id e0171241Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Placoderms are considered as the first jawed vertebrates and constitute a paraphyletic group in the stem-gnathostome grade. The acanthothoracid placoderms are among the phylogenetically most basal and morphologically primitive gnathostomes, but their neurocranial anatomy is poorly understood. Here we present a near-complete three-dimensional skull of Romundina stellina, a small Early Devonian acanthothoracid from the Canadian Arctic Archipelago, scanned with propagation phase contrast microtomography at a 7.46 mu m isotropic voxel size at the European Synchrotron Radiation Facility, Grenoble, France. This is the first model of an early gnathostome skull produced using this technique, and as such represents a major advance in objectivity compared to past descriptions of placoderm neurocrania on the basis of grinding series. Despite some loss of material along an oblique crack, most of the internal structures are remarkably preserved, and most of the missing structures can be reconstructed by symmetry. This virtual approach offers the possibility to connect with certainty all the external foramina to the blood and nerve canals and the central structures, and thus identify accurate homologies without destroying the specimen. The high level of detail enables description of the main arterial, venous and nerve canals of the skull, and other perichondrally ossified endocranial structures such as the palatoquadrate articulations, the endocranial cavity and the inner ear cavities. The braincase morphology appears less extreme than that of Brindabellaspis, and is in some respects more reminiscent of a basal arthrodire such as Kujdanowiaspis.

  • 53.
    Dupret, Vincent
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Goujet, Daniel
    Muséum National D'Histoire Naturelle, Paris, France.
    Tafforeau, Paul
    European Synchrotron Radiation Facility, Grenoble, France.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Being Romundina stellina Ørvig, 1975 (Vertebrate, Placodermi, Acanthothoraci): itracranial anatomy of one of the deepest gnathostomes revealed by synchrotron tomograpy in phase contrast protocole2012Ingår i: / [ed] Malvesy, T., Gauthrot, M., Fuchs, C., Berthoz, A., Blieck, A., Becker, D., Buffetaut, E., Mazin, J. -M.,, Montbéliard, 2012, s. 19-19Konferensbidrag (Refereegranskat)
    Abstract [en]

    Dans la peau de Romundina stellina Ørvig, 1975 (Vertebrata, Placodermi, Acanthothoraci)

    Anatomie crânienne d'un des premiers gnathostomes révélée par tomographie synchrotron en contraste de phase

     Being Romundina stellina Ørvig, 1975  (Vertebrata, Placodermi, Acanthothoraci)

    Intracranial anatomy of one of the deepest gnathostomes revealed by synchrotron tomography in phase contrast protocole

     

     

    The acanthothoracid placoderms (armored fishes) are the most basal and primitive gnathostomes (jawed vertebrates; 1). However, their endocranial morphology is poorly understood, and only one genus (Brindabellaspis) has been described thoroughly (2).

    Here we present the 3D reconstruction of a subcomplete skull of Romundina stellina Ørvig, 3, from the Lochkovian of Prince of Wales Island, Canadian Arctic Archipelago. The specimen was imaged in 3D with propagation phase contrast microtomography (4) on the ID19 beamline of the ESRF, using a 7.45 µm isotropic voxel size.

    Most features are properly preserved and most of the missing structures can be virtually rebuilt by symmetry. Another advantage of this virtual approach is the possibility of connecting with certainty all the external foramina to the blood and nerve canals and the central/internal structures, and hence to identify accurate homologies without destroying the specimen. Ørvig’s original assumptions can now be checked with confidence.

    The vasculature of the dermal bones, rendered in detail, allowed a better understanding of plate growth. It permits the visualization of dermal bone establishment over perichondral bone (5).

    The high level of details of this model reveals that between the trigeminal and vagus nerve (and the inner ears), the perichondral bone wrapping the endocranial cavity shows a “lace” pattern, unknown so far in vertebrates (presumably because of the lack of data). The significance of this character is unclear, but it is definitely not an artifact of taphonomy or scanning.

     

    References

    1          Janvier, P. Early Vertebrates. Clarendon Press edn, Vol. 1 (Oxford Science Publications, 1996).

    2          Young, G. C. A new Early Devonian placoderm from New South Wales, Australia, with a discussion of placoderm phylogeny. Palaeontographica (A) 167, 10–76 (1980).

    3          Ørvig, T. Description, with special reference to the dermal skeleton, of a new Radotinid arthrodire from the Gedinnian of Arctic Canada. Extrait des Colloques internationaux du Centre National de la Recherche Scientifique - Problèmes actuels de Paléontologie - Evolution des Vertébrés 218, 41–71 (1975).

    4          Tafforeau, P. et al. Applications of X-ray synchrotron microtomography for non-destructive 3D studies of paleontological specimens. Applied Physics A - Materials Science & Processing 83, 195–202 (2006).

    5          Dupret, V., Sanchez, S., Goujet, D., Tafforeau, P. & Ahlberg, P. Bone vascularization and growth in placoderms (Vertebrata): the example of the premedian plate of Romundina stellina Ørvig, 1975 Comptes Rendus Palevol 9, 369–375 (2010).

     

     

  • 54.
    Dupret, Vincent
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Goujet, Daniel
    Muséum National D'Histoire Naturelle, Paris, France.
    Tafforeau, Paul
    European Synchrotron Radiation Facility, Grenoble, France.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Fossil early vertebrates shed lights on the origin of the gnathostome face2013Ingår i: Program and Abstracts of the 10th International Congress of Vertebrate Morphology, Barcelona, Spain, 2013, s. 245-245Konferensbidrag (Refereegranskat)
    Abstract [en]

    Jawless cyclostomes and jawed gnathostomes show very different face patterns. Cyclostomes have a single median nasohypophysial duct, an anterior hypophysis and a short telencephalon, while gnathostomes have a pair of nasal sacs opening externally, a more posterior separate hypophysis open in the palate and a longer telencephalon.

    Embryonic processes differ as well. In cyclostomes, premandibular crest cells migrate forwards either side of the nasohypophysial placode to form the upper lip; in gnathostomes they migrate between the hypophysial and nasal placodes to form the trabecular region. Supraoptic neural crest remains posterior to the nasohypophysial duct in cyclostomes; it moves forward to create the nasal capsules in gnathostomes.

    Some fossil forms illustrate a transition between these two patterns.

    The jawless galeaspid Shuyu (-430 Ma) has a nasohypophysial duct, short telencephalon, and anteriorly oriented hypophysis, but the paired nasal sacs and hypophysis are separated by a rudimentary trabecula.

    The jawed primitive placoderm Romundina (-415 Ma) shows a cranial cavity reminiscent of that of Shuyu (anteriorly directed hypophysis, very short telencephalon). The trabecular region is long and wide, the nasal capsule is small and located far behind the tip of the snout but just in front of the orbits. We interpret these features as uniquely primitive among gnathostomes. The premandibular crest of Romundina formed a trabecular region extending as anteriorly as the tip of the snout (like in extant cyclostome and the fossil Shuyu). The position of the nasal capsule suggests that the supraoptic crest had not migrated forwards.

    We suggest that the evolutionary sequence for the creation of the extant gnathostome face from a cyclostome pattern involved 1) separation of the nasal and hypophysial placodes (galeaspids), 2) loss of the nasohypophysial duct (placoderms), and 3) lengthening of the telencephalon and the migration of the nasal capsules to the snout tip.

  • 55.
    Dupret, Vincent
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Goujet, Daniel
    Muséum National D'Histoire Naturelle, Paris, France.
    Tafforeau, Paul
    European Synchrotron Radiation Facility, Grenoble, France.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Fossils of early vertebrates and the evolution of the gnathostome face revealed by Synchrotron imaging2013Ingår i: Programme and Abstracts / [ed] Stig Walsh, Nick Fraser, Stephen Brusatte, Jeff Liston, Vicen Carrió, Edinburgh, U.K., 2013, s. 21-21Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cyclostomes and gnathostomes have distinct face patterns. Cyclostomes possess a median nasohypophysial duct, an anterior hypophysis and a short telencephalon, contra gnathostomes possessing a pair of nasal sacs opening externally, a separate posterior hypophysis opening onto the palate and a long telencephalon. Embryonic development also differs. In cyclostomes, premandibular crest cells migrate forwards either side of the nasohypophysial placode, forming an upper lip; in gnathostomes they migrate between the hypophysial and nasal placodes forming the trabecular region. Supraoptic neural crest remains posterior to the nasohypophysial duct in cyclostomes but moves forward to create the nasal capsules in gnathostomes. Fossil stem gnathostomes illustrate a transitional sequence between these two patterns: 1) The galeaspid Shuyu (jawless stem gnathostome): nasohypophysial duct, short telencephalon, and anteriorly oriented hypophysis as in a cyclostome, but paired nasal sacs and hypophysis separated by a rudimentary trabecula. 2) The primitive placoderm Romundina (jawed stem gnathostome): short telencephalon, anteriorly directed hypophysis, trabecular region long and wide, nasal capsule located far behind the tip of the snout but just in front of the orbits. These features are interpreted as uniquely primitive among gnathostomes. The trabeculae of Romundina form an extensive precerebral region resembling the upper lip of extant cyclostomes and Shuyu. The position of the nasal capsule suggests that the supraoptic crest had not migrated forwards. 3) The arthrodire Kujdanowiapsis (a more derived placoderm): short telencephalon and vertically oriented hypophysis. The trabecula has been shortened anteriorly, making the nasal capsule terminal. These positional relationships are maintained in crown gnathostomes.

  • 56.
    Dupret, Vincent
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Goujet, Daniel
    Muséum National D'Histoire Naturelle, Paris, France.
    Tafforeau, Paul
    European Synchrotron Radiation Facility, Grenoble, France.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Internal structures of the skull of Romundina stellina Ørvig 1975 (Vertebrata, Placodermi, Acanthothoraci) revealed by phase contrast synchrotron scanning2011Ingår i: CAVEPS Perth 2011: Conference on Australasian Vertebrate Evolution Palaeontology and Systematics, Perth, April 27th-30th : programme, abstracts / [ed] Geological Survey of Western Australia, East Perth, W.A: Geological Survey of Western Australia , 2011, s. 30-30Konferensbidrag (Refereegranskat)
  • 57.
    Dupret, Vincent
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Goujet, Daniel
    Muséum National D'Histoire Naturelle, Paris, France.
    Tafforeau, Paul
    European Synchrotron Radiation Facility, Grenoble, France.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Intracranial anatomy of Romundina stellina Ørvig 1975 (Vertebrata, Placodermi, Acanthothoraci) revealed by phase contrast synchrotron imaging2011Ingår i: Abstracts: The 2nd Wiman meeting Carl Wiman's Legacy: 100 years of Swedish Palaeontology: Uppsala 17–18 November 2011 / [ed] Benjamin P. Kear, Michael Streng, 2011, s. 6-6Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Acanthothoracid placoderms are considered amongst the most basal of primitive gnathostomes. However, their endocranial morphology is poorly understood, and only one genus (Brindabellaspis) has been described in detail. Here we present a synchrotrongenerated 3D reconstruction of a nearly complete skull of Romundina stellina, a taxon established in 1975 by the Norwegian-born Swedish palaeontologist Tor Ørvig based on remains from the Lochkovian (Lower Devonian) of Prince of Wales Island, Canadian Arctic Archipelago. The specimen was imaged with propagation phase contrast microtomography on the ID19 beamline of the ESRF, using a 7.45 µm isotropic voxel size. Most structural features of the fossil are very well preserved, allowing missing elements to be virtually rebuilt by symmetry. This permitted reconnection of the external foramina and blood vessel/nerve canals, and alignment of the central/internal structures. Expanding on Ørvig’s original interpretations, our virtual models show the vasculature of the skull bones, and indicate establishment of successive dermal over perichondral bone layers. The perichondral bone wrapping the endocranial cavity, in between the trigeminal and vagus nerve (and the inner ears), shows a “lace” pattern, which is otherwise unknown in vertebrates (presumably because of the lack of data). The significance of this trait is unclear but it is not an artifact of taphonomy or scanning.

  • 58.
    Dupret, Vincent
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Goujet, Daniel
    Muséum National D'Histoire Naturelle, Paris, France.
    Tafforeau, Paul
    European Synchrotron Radiation Facility, Grenoble, France.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Structures intra-crâniennes de Romundina stellina Ørvig 1975 (Vertebrata, Placodermi, Acanthothoraci) révélé par tomographie synchrotron en contraste de phase2012Konferensbidrag (Refereegranskat)
    Abstract [fr]

    Les placodermes acanthothoracides sont parmi les vertébrés gnathostomes les plus basaux phylogénetiquement et morphologiquement. Néanmoins, une bonne connaissance anatomie crânienne fait défaut, et à ce jour un seul genre (Brindabellaspis) a été décrit en détails. Nous présentons le modèle en 3 dimensions d’un crâne presque complet de Romundina stellina, un petit acanthothoracide du Dévonien inférieur de l’Archipel Arctique Canadien, décrit originellement par Ørvig (1975). Le spécimen a été microtomographié sur la ligne de faisceau ID 19 de l’ESRF de Grenoble (European Synchrotron Radiation Facility), en protocole de contraste de phase, avec un voxel isotrope de 7,45 micromètres.

    Malgré une cassure oblique, la plupart des structures peuvent être reconstruites par symétrie. Chaque nerf crânien peut être suivi entre la cavité encéphalique et les murs du neurocrâne composés d’os périchondral. Il en est de même pour les vaisseaux sanguins. La détermination des homologies en est donc facilitée, tout en assurant la non destruction du spécimen. Les hypothèses d’homologies formulées par Ørvig peuvent être traitées en toute confidence.

    La couche d’os périchondrale entourant la cavité encéphalique n’est pas homogène mais présente un aspect en dentelle entre les nerfs trijumeaux (V) et vague (X) ; il en est de même pour les oreilles internes, dont les canaux semi-circulaires ne sont pas ossifiés du tout latéralement et dorsalement. Cet aspect en dentelle n’est ni un artefact de fossilisation, de préservation ou de modélisation, et n’a jamais été retrouvé sur aucun autre vertébré (mais l’échantillonnage à cette résolution fait encore cruellement défaut).

    Les canalicules nerveux reliés aux neuromastes de la ligne latérale permettent de retracer leur origine à une branche du nerf facial (VII). Les deux oreilles internes ont été reconstruites avec précision et montrent une morphologie primitive.

    Le réseau vasculaire de l’os dermique a été reconstruit en détails, et permet de mettre en évidence les limites de plaques du toit crânien, invisibles autrement. Ce réseau vasculaire est relié à des veines drainant la bordure de la boîte crânienne ou à une branche de la veine jugulaire. La courbure de ces vaisseaux autour de l’oreille interne pourrait démarquer la limite entre la capsule otique et l’arc hyoïdien qui s’y attachait.

    D’un point de vue général, la morphologie de la boîte crânienne et de ses structures associées paraît moins primitive (et moins extrême) que celle de Brindabellaspis, mais rappelle au contraire plus les structures observées chez le placoderme arthrodire Kujdanowiaspis, plus dérivé.

    Ces différences mettent en lumière les premiers stades de l’évolution du crâne des placodermes, donc des gnathostomes. 

  • 59.
    Dupret, Vincent
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi.
    Goujet, Daniel
    Muséum National D'Histoire Naturelle, Paris, France.
    Tafforeau, Paul
    European Synchrotron Radiation Facility, Grenoble, France.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    The cranial anatomy of Romundina stellina Ørvig, 1975 (Vertebrata, Placodermi, Acanthothoraci) revealed by phase contrast synchrotron scanning2010Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    The acanthothoracid placoderms are among the most phylogenetically basal and morphologically primitive gnathostomes. However, their endocranial anatomy is not well understood; only one genus, Brindabellaspis, has been described in detail. Here we present a near-complete three-dimensional skull of Romundina stellina, a small Early Devonian acanthothoracid from the Canadian Arctic Archipelago, scanned at the European Synchrotron Radiation Facility, Grenoble, France, at a 7.45 µm resolution using propagation phase contrast. Despite some loss of material along an oblique crack, most of the internal structures are remarkably preserved. Each postethmoid cranial and craniospinal nerve can be followed between the well-preserved endocranial cavity and the walls of the perichondrally ossified neurocranium. The minute nerve canals that supplied the neuromast organs of the sensory line system are preserved and can in the postorbital area be traced directly to a branch of the facial nerve. Both inner ears are present. The vascular mesh of the dermal bones has been reconstructed in detail, rendering visible the dermal plate boundaries of the skull roof, and is shown to connect to larger internal veins that drain to the edge of the braincase or into the jugular vein canal. The curvature of the latter vessels parallels the outer surface of the inner ear and may demarcate the boundary between otic capsule proper and applied hyoid arch material. Overall, the braincase morphology appears less extreme (and less primitive?) than that of Brindabellaspis, in some respects more reminiscent of a primitive arthrodire such as Kujdanowiaspis. These differences may illuminate the earliest stages of placoderm cranial evolution.

  • 60.
    Dupret, Vincent
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Goujet, Daniel
    Muséum National D'Histoire Naturelle, Paris, France.
    Tafforeau, Paul
    European Synchrotron Radiation Facility, Grenoble, France.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    The origin of the jawed vertebrate face: new insights from a synchrotron scanned skull of the primituve placoderm Romundina2013Ingår i: Program and abstracts / [ed] Maxwell, E., Miller-Camp, J., Anemone, R.,, Los Angeles, U.S.A., 2013, s. 118-118Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Jawless cyclostomes and jawed gnathostomes show very different face patterns.Cyclostomes have a single median nasohypophysial duct, an anterior hypophysis and ashort telencephalon, while gnathostomes have a pair of nasal sacs opening externally, amore posterior separate hypophysis opening in the palate and a longer telencephalon.Embryonic processes differ as well. In cyclostomes, infraorbital premandibular crest cellsmigrate forwards either side of the nasohypophysial placode to form the upper lip; ingnathostomes they migrate between the hypophysial and nasal placodes to form thetrabecular-ethmoid region. Supraoptic neural crest remains posterior to thenasohypophysial duct in cyclostomes; it moves forward to create the nasal capsules ingnathostomes. Some fossil forms illustrate a sequenced transition between these twopatterns. The Silurian galeaspid (jawless stem gnathostome) Shuyu has a nasohypophysialduct, a short telencephalon, and an anteriorly oriented hypophysis, but the paired nasalsacs and hypophysis are separated by a rudimentary trabecula. A synchrotron scannedskull of the primitive Early Devonian placoderm (jawed stem gnathostome) Romundinashows a cranial cavity reminiscent of that of Shuyu (anteriorly directed hypophysis, veryshort telencephalon). The trabecular-ethmoid region is long and wide, extending anteriorto the small nasal capsule which is located just in front of the orbits. We interpret thesefeatures as uniquely primitive among gnathostomes. In size and position the trabecularethmoidregion of Romundina resembles the upper lip of cyclostomes and Shuyu,suggesting a cyclostome-like pattern of proliferation coupled with a gnathostome-likemigration path for the premandibular crest. The position of the nasal capsule suggests thatthe supraoptic crest had not migrated forwards. A new phylogenetic analysis suggeststhat the evolutionary sequence for the creation of the extant gnathostome face from acyclostome ancestral pattern involved 1) separation of the nasal and hypophysialplacodes (galeaspids: Shuyu), 2) loss of the nasohypophysial duct (basal placoderms:antiarchs, Brindabellaspis, Romundina), 3) shortening and narrowing of the trabecularethmoidregion, the nasal capsule becoming anterior (derived placoderms such asarthrodires); 4) lengthening of the telencephalon (crown gnathostomes). Galeaspid facialanatomy appears closer to gnathostomes than that of osteostracans, but it is unclearwhether osteostracans are primitive or autapomorphic in this respect.

  • 61.
    Dupret, Vincent
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Goujet, Daniel
    Muséum National D'Histoire Naturelle, Paris, France.
    Tafforeau, Paul
    European Synchrotron Radiation Facility, Grenoble, France.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    The Placoderm Romundina and the Origin of the Gnathostome Face2013Ingår i: The Making of a Vertebrate / [ed] Toyama, Y., Ito, A., Kobe, Japan, 2013, s. 110-111Konferensbidrag (Refereegranskat)
    Abstract [en]

    Facial anatomy differs fundamentally between extant jawless and jawed vertebrates (cyclostomes and gnathostomes). Cyclostomes have a median nasohypophysial duct; gnathostomes have separate nasal sacs opening externally, and a palatal hypophysis. Premandibular crest cells migrate forwards either side of the nasohypophysial placode to form the upper lip in cyclostomes, but between the hypophysial and nasal placodes to form the trabecular region in gnathostomes1,2. Supraoptic neural crest remains posterior to the nasohypophysial duct in cyclostomes but moves forward to create the nasal capsules of gnathostomes1,2. In cyclostomes the telencephalon is much shorter than in gnathostomes and the hypophysis is relatively anterior. The galeaspid Shuyu, a 430 million year old jawless vertebrate, partly bridges the gap between these facial architectures3. Shuyu has a nasohypophysial duct, short telencephalon, and anteriorly oriented hypophysis, but the nasal sacs and hypophysis are separated by a rudimentary trabecula.

                          Here we present the placoderm Romundina, a 415 million year old jawed vertebrate that represents a further transitional step. Its cranial cavity is similar to that of Shuyu, with an anteriorly directed hypophysis and very short telencephalon. The trabecular region is exceptionally long and wide whereas the nasal capsule (demarcated by a fissure) is small and located far behind the tip of the snout. The upper jaw articulates with the side of the trabecular region to its anterior end, without contacting the nasal capsule. We interpret these features as uniquely primitive among gnathostomes. The premandibular crest of Romundina formed a trabecular region, but like the upper lip of cyclostomes and Shuyu it was a large structure reaching the tip of the snout. The position of the nasal capsule suggests that the supraoptic crest had not migrated forwards. We suggest that during the creation of the gnathostome face, separation of the nasal and hypophysial placodes was followed by loss of the nasohypophysial duct, with lengthening of the telencephalon and migration of the nasal capsules to the snout tip as the final step.

  • 62.
    Dupret, Vincent
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Goujet, Daniel
    Muséum National D'Histoire Naturelle, Paris, France.
    Tafforeau, Paul
    European Synchrotron Radiation Facility, Grenoble, France.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    The Placoderm Romundina and the Origin of the Gnathostome Face2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Facial anatomy differs fundamentally between extant jawless and jawed vertebrates (cyclostomes and gnathostomes). Cyclostomes have a median nasohypophysial duct; gnathostomes have separate nasal sacs opening externally, and a palatal hypophysis. Premandibular crest cells migrate forwards either side of the nasohypophysial placode to form the upper lip in cyclostomes, but between the hypophysial and nasal placodes to form the trabecular region in gnathostomes1,2. Supraoptic neural crest remains posterior to the nasohypophysial duct in cyclostomes but moves forward to create the nasal capsules of gnathostomes1,2. In cyclostomes the telencephalon is much shorter than in gnathostomes and the hypophysis is relatively anterior. The galeaspid Shuyu, a 430 million year old jawless vertebrate, partly bridges the gap between these facial architectures3. Shuyu has a nasohypophysial duct, short telencephalon, and anteriorly oriented hypophysis, but the nasal sacs and hypophysis are separated by a rudimentary trabecul. Here we present the placoderm Romundina, a 415 million year old jawed vertebrate that represents a further transitional step. Its cranial cavity is similar to that of Shuyu, with an anteriorly directed hypophysis and very short telencephalon. The trabecular region is exceptionally long and wide whereas the nasal capsule (demarcated by a fissure) is small and located far behind the tip of the snout. The upper jaw articulates with the side of the trabecular region to its anterior end, without contacting the nasal capsule. We interpret these features as uniquely primitive among gnathostomes. The premandibular crest of Romundina formed a trabecular region, but like the upper lip of cyclostomes and Shuyu it was a large structure reaching the tip of the snout. The position of the nasal capsule suggests that the supraoptic crest had not migrated forwards. We suggest that during the creation of the gnathostome face, separation of the nasal and hypophysial placodes was followed by loss of the nasohypophysial duct, with lengthening of the telencephalon and migration of the nasal capsules to the snout tip as the final step.

     

    1. Kuratani, S. et al. Phil. Trans. R. Soc. Lond. B 356, 1615-1632 (2001).

    2. Kuratani, S. et al. Nature (in press, doi:10.1038/nature11794).

    3. Gai, Z. et al. Nature 476, 324-327 (2011).

  • 63.
    Dupret, Vincent
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Goujet, Daniel
    Tafforeau, Paul
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    A primitive placoderm sheds light on the origin of the jawed vertebrate face2014Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 507, nr 7493, s. 500-503Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Extant vertebrates form two clades, the jawless Cyclostomata (lampreys and hagfishes) and the jawed Gnathostomata (all other vertebrates), with contrasting facial architectures(1,2). These arise during development from just a few key differences in the growth patterns of the cranial primordia: notably, the nasal sacs and hypophysis originate from a single placode in cyclostomes but from separate placodes in gnathostomes, and infraoptic ectomesenchyme migrates forward either side of the single placode in cyclostomes but between the placodes in gnathostomes(3-8). Fossil stem gnathostomes preserve cranial anatomies rich in landmarks that provide proxies for developmental processes and allow the transition from jawless to jawed vertebrates to be broken down into evolutionary steps(7,9-12). Here we use propagation phase contrast synchrotron microtomography to image the cranial anatomy of the primitive placoderm (jawed stem gnathostome) Romundina(13), and show that itcombines jawed vertebrate architecture with cranial and cerebral proportions resembling those of cyclostomes and the galeaspid (jawless stem gnathostome) Shuyu(11). This combination seems to be primitive for jawed vertebrates, and suggests a decoupling between ectomesenchymal growth trajectory, ectomesenchymal proliferation, and cerebral shape change during the origin of gnathostomes.

  • 64.
    Fadel, Alexandre
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi.
    Zigaite, Zivile
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Blom, Henning
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Perez-Huerta, Alberto
    Jeffries, Teresa
    Maersse, Tiiu
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Palaeoenvironmental signatures revealed from rare earth element (REE) compositions of vertebrate microremains of the Vesiku Bone Bed (Homerian, Wenlock), Saaremaa Island, Estonia2015Ingår i: Estonian journal of earth sciences, ISSN 1736-4728, E-ISSN 1736-7557, Vol. 64, nr 1, s. 36-41Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rare earth elements (REEs) have been analysed from fossil vertebrate microremains (thelodont scales) from the Vesiku Bone Bed, Saaremaa, Estonia, using in situ microsampling by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Well-preserved scales of three species of the genus Thelodus (T. carinatus, T. laevis and Thelodus sp.) show very uniform REE patterns with slightly lower overall REE concentrations in enameloid than in dentine, with enrichment in middle REEs, depletion in heavy REEs and pronounced negative europium anomaly, but no cerium anomaly. The results of this study suggest a similar diagenetic history and possibly contemporaneous habitats for all three Thelodus species, as well as possible suboxic to anoxic conditions of the bottom and pore waters during the formation of the Vesiku Bone Bed.

  • 65.
    Fiz-Palacios, Omar
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Systematisk biologi.
    Romeralo, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Systematisk biologi.
    Ahmadzadeh, Afsaneh
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Systematisk biologi.
    Weststrand, Stina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Systematisk biologi.
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Baldauf, Sandra
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Systematisk biologi.
    Did terrestrial diversification of amoebas (Amoebozoa) occur in synchrony with land plants?2013Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, nr 9, s. e74374-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Evolution of lineage diversification through time is an active area of research where much progress has been made in the last decade. Contrary to the situation in animals and plants little is known about how diversification rates have evolved in most major groups of protist. This is mainly due to uncertainty about phylogenetic relationships, scarcity of the protist fossil record and the unknown diversity within these lineages. We have analyzed the evolutionary history of the supergroup Amoebozoa over the last 1000 million years using molecular dating and species number estimates. After an origin in the marine environment we have dated the colonization of terrestrial habitats by three distinct lineages of Amoebozoa: Dictyostelia, Myxogastria and Arcellinida. The common ancestor of the two sister taxa, Dictyostelia and Myxogastria, appears to have existed before the colonization of land by plants. In contrast Arcellinida seems to have diversify in synchrony with land plant radiation, and more specifically with that of mosses. Detection of acceleration of diversification rates in Myxogastria and Arcellinida points to a co-evolution within the terrestrial habitats, where land plants and the amoebozoans may have interacted during the evolution of these new ecosystems.

  • 66.
    Gess, Robert
    et al.
    Rhodes Univ, Albany Museum, Grahamstown, South Africa;Rhodes Univ, Geol Dept, Grahamstown, South Africa.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    A tetrapod fauna from within the Devonian Antarctic Circle2018Ingår i: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 360, nr 6393, s. 1120-1124Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Until now, all known fossils of tetrapods (limbed vertebrates with digits) and near-tetrapods (such as Elpistostege, Tiktaalik, and Panderichthys) from the Devonian period have come from localities in tropical to subtropical paleolatitudes. Most are from Laurussia, a continent incorporating Europe, Greenland, and North America, with only one body fossil and one footprint locality from Australia representing the southern supercontinent Gondwana. Here we describe two previously unknown tetrapods from the Late Devonian (late Famennian) Gondwana locality of Waterloo Farm in South Africa, then located within the Antarctic Circle, which demonstrate that Devonian tetrapods were not restricted to warm environments and suggest that they may have been global in distribution.

  • 67.
    Gierlinski, Gerard D.
    et al.
    Moab Giants, 112W-SR 313 Moab, Moab, UT 84532 USA;Polish Res Inst, Polish Geol Inst, Rakowiecka 4, PL-00975 Warsaw, Poland.
    Niedzwiedzki, Grzegorz
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Lockley, Martin G.
    Moab Giants, 112W-SR 313 Moab, Moab, UT 84532 USA;Univ Colorado Denver, Dinosaur Tracks Museum, POB 173364, Denver, CO 80217 USA.
    Athanassiou, Athanassios
    Ephorate Palaeoanthropol Speleol, Hellen Minist Culture & Sports, Ardittou 34B, GR-11636 Athens, Greece.
    Fassoulas, Charalampos
    Univ Crete, Nat Hist Museum, Iraklion 71409, Greece.
    Dubicka, Zofia
    Univ Warsaw, Fac Geol, Zwirki & Wiguty 93, PL-02089 Warsaw, Poland.
    Boczarowski, Andrzej
    Park Sci & Human Evolut, 1 Maja 10, PL-46040 Krasiejow, Poland;Moab Giants, 112W-SR 313 Moab, Moab, UT 84532 USA;Stowarzyszenie Delta Delta Assoc, Sandomierska 4, PL-27400 Ostrowiec Swietokrzyski, Poland;Univ Silesia, Fac Earth Sci, Bedzinska 60, PL-41200 Sosnowiec, Poland.
    Bennett, Matthew R.
    Bournemouth Univ, Inst Studies Landscapes & Human Evolut, Poole BH12 5BB, Dorset, England.
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Possible hominin footprints from the late Miocene (c. 5.7 Ma) of Crete?2017Ingår i: Proceedings Geological Association, ISSN 0016-7878, Vol. 128, nr 5-6, s. 697-710Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We describe late Miocene tetrapod footprints (tracks) from the Trachilos locality in western Crete (Greece), which show hominin-like characteristics. They occur in an emergent horizon within an otherwise marginal marine succession of Messinian age (latest Miocene), dated to approximately 5.7 Ma (million years), just prior to the Messinian Salinity Crisis. The tracks indicate that the trackmaker lacked claws, and was bipedal, plantigrade, pentadactyl and strongly entaxonic. The impression of the large and non-divergent first digit (hallux) has a narrow neck and bulbous asymmetrical distal pad. The lateral digit impressions become progressively smaller so that the digital region as a whole is strongly asymmetrical. A large, rounded ball impression is associated with the hallux. Morphometric analysis shows the footprints to have outlines that are distinct from modern non-hominin primates and resemble those of hominins. The interpretation of these footprints is potentially controversial. The print morphology suggests that the trackmaker was a basal member of the Glade Hominini, but as Crete is some distance outside the known geographical range of pre-Pleistocene hominins we must also entertain the possibility that they represent a hitherto unknown late Miocene primate that convergently evolved human-like foot anatomy.

  • 68.
    Grahn, Jessica
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi.
    Blom, Henning
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    The primitive antiarch Yunnanolepis from China: a microtomographic study2011Ingår i: Abstracts: The 2nd Wiman meeting : Carl Wiman's Legacy : 100 years of Swedish Palaeontology : Uppsala 17–18 November 2011 / [ed] Benjamin P. Kear and Michael Streng, 2011, s. 8-9Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Placoderms first appeared during the Silurian, after which they diversified and spread rapidly to dominate the Devonian seas. One of the stratigraphically earliest placoderms is Yunnanolepis, a primitive antiarch from the Early Devonian of China and Vietnam. To date, little specific research has been devoted to yunnanolepids, and previous assessments have utilised conventional descriptive methods. In contrast, this study constructed exceptionally detailed 3D-models based on a synchrotron X-ray microtomographic scan series of Yunnanolepis material from the Muséum National d'Histoire Naturelle, Paris. Our novel data set revealed a well-preserved anterior ventrolateral plate (AVL) with the opening for the pectoral fin, and other hitherto unknown structures such as the transverse crista, postbranchial lamina, and external ornamentation. The first 3D image of the mysterious ’Chang's apparatus’ was also generated. ‘Chang's apparatus’ in known only in Yunnanolepididae, and its function remains unknown. Disarticulated tooth plates and scales of other gnathostomes were also found with the specimen, and include very small AVL plates of young antiarchs. These lack ornamentation and their postbranchial laminae are weakly developed compared to osteologically more mature individuals.

  • 69.
    Habicher, Judith
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Haitina, Tatjana
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Eriksson, Inger
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Holmborn, Katarina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Dierker, Tabea
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Ahlberg, Per E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Ledin, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Chondroitin / Dermatan Sulfate Modification Enzymes in Zebrafish Development2015Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, nr 3, artikel-id e0121957Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chondroitin/dermatan sulfate (CS/DS) proteoglycans consist of unbranched sulfated polysaccharide chains of repeating GalNAc-GlcA/IdoA disaccharide units, attached to serine residues on specific proteins. The CS/DS proteoglycans are abundant in the extracellular matrix where they have essential functions in tissue development and homeostasis. In this report a phylogenetic analysis of vertebrate genes coding for the enzymes that modify CS/DS is presented. We identify single orthologous genes in the zebrafish genome for the sulfotransferases chst7, chst11, chst13, chst14, chst15 and ust and the epimerase dse. In contrast, two copies were found for mammalian sulfotransferases CHST3 and CHST12 and the epimerase DSEL, named chst3a and chst3b, chst12a and chst12b, dsela and dselb, respectively. Expression of CS/DS modification enzymes is spatially and temporally regulated with a large variation between different genes. We found that CS/DS 4-O-sulfotransferases and 6-O-sulfotransferases as well as CS/DS epimerases show a strong and partly overlapping expression, whereas the expression is restricted for enzymes with ability to synthesize di-sulfated disaccharides. A structural analysis further showed that CS/DS sulfation increases during embryonic development mainly due to synthesis of 4-O-sulfated GalNAc while the proportion of 6-O-sulfated GalNAc increases in later developmental stages. Di-sulfated GalNAc synthesized by Chst15 and 2-O-sulfated GlcA/IdoA synthesized by Ust are rare, in accordance with the restricted expression of these enzymes. We also compared CS/DS composition with that of heparan sulfate (HS). Notably, CS/DS biosynthesis in early zebrafish development is more dynamic than HS biosynthesis. Furthermore, HS contains disaccharides with more than one sulfate group, which are virtually absent in CS/DS.

  • 70. Hadzhiev, Yavor
    et al.
    Lele, Zsolt
    Schindler, Simon
    Wilson, Stephen W.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för fysiologi och utvecklingsbiologi, Evolutionär organismbiologi.
    Strähle, Uwe
    Müller, Ferenc
    Hedgehog signaling patterns the outgrowth of unpaired skeletal appendages in zebrafish2007Ingår i: BMC Developmental Biology, ISSN 1471-213X, E-ISSN 1471-213X, Vol. 7, s. 75-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background

    Little is known about the control of the development of vertebrate unpaired appendages such as the caudal fin, one of the key morphological specializations of fishes. Recent analysis of lamprey and dogshark median fins suggests the co-option of some molecular mechanisms between paired and median in Chondrichthyes. However, the extent to which the molecular mechanisms patterning paired and median fins are shared remains unknown.

    Results

    Here we provide molecular description of the initial ontogeny of the median fins in zebrafish and present several independent lines of evidence that Sonic hedgehog signaling emanating from the embryonic midline is essential for establishment and outgrowth of the caudal fin primordium. However, gene expression analysis shows that the primordium of the adult caudal fin does not harbor a Sonic hedgehog-expressing domain equivalent to the Shh secreting zone of polarizing activity (ZPA) of paired appendages.

    Conclusion

    Our results suggest that Hedgehog proteins can regulate skeletal appendage outgrowth independent of a ZPA and demonstrates an unexpected mechanism for mediating Shh signals in a median fin primordium. The median fins evolved before paired fins in early craniates, thus the patterning of the median fins may be an ancestral mechanism that controls the outgrowth of skeletogenic appendages in vertebrates.

  • 71.
    Haitina, Tatjana
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Qu, Qinming
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Identification of enamel matrix protein genes in the genome of spotted gar Lepisosteus oculatus 2015Konferensbidrag (Övrigt vetenskapligt)
  • 72.
    Holmborn, Katarina
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Habicher, Judith
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Kasza, Zsolt
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Eriksson, Anna S.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Gorniok, Beata Filipek
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Gopal, Sandeep
    Couchman, John R.
    Ahlberg, Per Erik
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Wiweger, Malgorzata
    Spillmann, Dorothe
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Kreuger, Johan
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Ledin, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    On the Roles and Regulation of Chondroitin Sulfate and Heparan Sulfate in Zebrafish Pharyngeal Cartilage Morphogenesis2012Ingår i: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 287, nr 40, s. 33905-33916Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present study addresses the roles of heparan sulfate (HS) proteoglycans and chondroitin sulfate (CS) proteoglycans in the development of zebrafish pharyngeal cartilage structures. uxs1 and b3gat3 mutants, predicted to have impaired biosynthesis of both HS and CS because of defective formation of the common proteoglycan linkage tetrasaccharide were analyzed along with ext2 and extl3 mutants, predicted to have defective HS polymerization. Notably, the effects on HS and CS biosynthesis in the respective mutant strains were shown to differ from what had been hypothesized. In uxs1 and b3gat3 mutant larvae, biosynthesis of CS was shown to be virtually abolished, whereas these mutants still were capable of synthesizing 50% of the HS produced in control larvae. extl3 and ext2 mutants on the other hand were shown to synthesize reduced amounts of hypersulfated HS. Further, extl3 mutants produced higher levels of CS than control larvae, whereas morpholino-mediated suppression of csgalnact1/csgalnact2 resulted in increased HS biosynthesis. Thus, the balance of the Extl3 and Csgalnact1/Csgalnact2 proteins influences the HS/CS ratio. A characterization of the pharyngeal cartilage element morphologies in the single mutant strains, as well as in ext2;uxs1 double mutants, was conducted. A correlation between HS and CS production and phenotypes was found, such that impaired HS biosynthesis was shown to affect chondrocyte intercalation, whereas impaired CS biosynthesis inhibited formation of the extracellular matrix surrounding chondrocytes.

  • 73.
    Jeffery, Jonathan E.
    et al.
    Univ Bristol, Sch Earth Sci, Bristol BS8 1TQ, Avon, England.
    Storrs, Glenn W.
    Cincinnati Museum Ctr, Cincinnati, OH 45203 USA.
    Holland, Timothy
    Kronosaurus Korner, Richmond, Qld 4822, Australia.
    Tabin, Clifford J.
    Harvard Med Sch, Dept Genet, Boston, MA 02115 USA.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Unique pelvic fin in a tetrapod-like fossil fish, and the evolution of limb patterning2018Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 115, nr 47, s. 12005-12010Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    All living tetrapods have a one-to-two branching pattern in the embryonic proximal limb skeleton, with a single element at the base of the limb (the humerus or femur) that articulates distally with two parallel radials (the ulna and radius or the tibia and fibula). This pattern is also seen in the fossilized remains of stem-tetrapods, including the fishlike members of the group, in which despite the absence of digits, the proximal parts of the fin skeleton clearly resemble those of later tetrapods. However, little is known about the developmental mechanisms that establish and canalize this highly conserved pattern. We describe the well-preserved pelvic fin skeleton of Rhizodus hibberti, a Carboniferous sarcopterygian (lobe-finned) fish, and member of the tetrapod stem group. In this specimen, three parallel radials, each robust with a distinct morphology, articulate with the femur. We review this unexpected morphology in a phylogenetic and developmental context. It implies that the developmental patterning mechanisms seen in living tetrapods, now highly constrained, evolved from mechanisms flexible enough to accommodate variation in the zeugopod (even between pectoral and pelvic fins), while also allowing each element to have a unique morphology.

  • 74.
    Jerve, Anna
    et al.
    Imperial Coll London, Biol Dept, Silwood Pk Campus,Buckhurst Rd, Ascot SL5 7PY, Berks, England.
    Bremer, Oskar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab. European Synchrotron Radiat Facil, 71 Ave Martyrs, F-38000 Grenoble, France.
    Ahlberg, Per E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Morphology and histology of acanthodian fin spines from the late Silurian Ramsåsa E locality, Skåne, Sweden2017Ingår i: Palaeontologia Electronica, ISSN 1935-3952, E-ISSN 1094-8074, Vol. 20, nr 3, artikel-id 56AArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    Comparisons of acanthodians to extant gnathostomes are often hampered by the paucity of mineralized structures in their endoskeleton, which limits the potential preservation of phylogenetically informative traits. Fin spines, mineralized dermal structures that sit anterior to fins, are found on both stem-and crown-group gnathostomes, and represent an additional potential source of comparative data for studying acanthodian relationships with the other groups of early gnathostomes. An assemblage of isolated acanthodian fin spines from the late Silurian Ramsasa site E locality (southern Sweden) has been reconstructed in 3D using propagation phase contrast synchrotron X-ray microtomography (PPC-SR mu CT). The aim is to provide morphological and taxo-nomical affinities for the spines by combining morphology and histology with the taxo-nomical framework previously established for the site mainly based on isolated scales. The high-resolution scans also enable investigations of the composition and growth of acanthodian fin spines when compared to similar studies of extinct and extant gnathostomes. In total, seven fin spine morphotypes that have affinities to both Climatiidae Berg 1940 and Ischnacanthiformes Berg 1940 are described. The majority are interpreted as median fin spines, but three possible paired spines are also identified. The spines display differences in their compositions, but generally agree with that presented for climatiids and ischnacanthiforms in previous studies. Their inferred growth modes appear to be more similar to those of fossil and extant chondrichthyan fin spines than to those described from placoderms and stem-osteichthyans, which is congruent with the emerging view of acanthodians as stem-chondrichthyans.

  • 75.
    Jerve, Anna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Johanson, Zerina
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Boisvert, Catherine
    Embryonic development of fin spines in Callorhinchus milii (Holocephali); implications for chondrichthyan fin spine evolution2014Ingår i: Evolution & Development, ISSN 1520-541X, E-ISSN 1525-142X, Vol. 16, nr 6, s. 339-353Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fin spines are commonly known from fossil gnathostomes (jawed vertebrates) and are usually associated with paired and unpaired fins. They are less common among extant gnathostomes, being restricted to the median fins of certain chondrichthyans (cartilaginous fish), including chimaerids (elephant sharks) and neoselachians (sharks, skates, and rays). Fin spine growth is of great interest and relevance but few studies have considered their evolution and development. We investigated the development of the fin spine of the chimaerid Callorhinchus milii using stained histological sections from a series of larval, hatchling, and adult individuals. The lamellar trunk dentine of the Callorhinchus spine first condenses within the mesenchyme, rather than at the contact surface between mesenchyme and epithelium, in a manner more comparable to dermal bone formation than to normal odontode development. Trabecular dentine forms a small component of the spine under the keel; it is covered externally with a thin layer of lamellar trunk dentine, which is difficult to distinguish in sectioned adult spines. We suggest that the distinctive characteristics of the trunk dentine may reflect an origin through co-option of developmental processes involved in dermal bone formation. Comparison with extant Squalus and a range of fossil chondrichthyans shows that Callorhinchus is more representative than Squalus of generalized chondrichthyan fin-spine architecture, highlighting its value as a developmental model organism.

  • 76.
    Jerve, Anna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Imperial Coll London, Dept Life Sci, Ascot, Berks, England.
    Qu, Qingming
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Univ Ottawa, Ctr Adv Res Environm Genom, Ottawa, ON, Canada.
    Sanchez, Sophie
    Uppsala universitet, Science for Life Laboratory, SciLifeLab. European Synchrotron Radiat Facil, Grenoble, France.
    Blom, Henning
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Three-dimensional paleohistology of the scale and median fin spine of Lophosteus superbus (Pander 1856)2016Ingår i: PeerJ, ISSN 2167-8359, E-ISSN 2167-8359, Vol. 4, artikel-id e2521Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lophosteus superbus is one of only a handful of probable stem-group osteichthyans known from the fossil record. First collected and described in the late 19th century from the upper Silurian Saaremaa Cliff locality in Estonia, it is known from a wealth of disarticulated scales, fin spines, and bone fragments. In this study we provide the first description of the morphology and paleohistology of a fin spine and scale from Lophosteus using virtual thin sections and 3D reconstructions that were segmented using phase-contrast synchrotron X-ray microtomography. These data reveal that both structures have fully or partially buried odontodes, which retain fine morphological details in older generations, including sharp nodes and serrated ridgelets. The vascular architecture of the fin spine tip, which is composed of several layers of longitudinally directed bone vascular canals, is much more complex compared to the bulbous horizontal canals within the scale, but they both have distinctive networks of ascending canals within each individual odontode. Other histological characteristics that can be observed from the data are cell spaces and Sharpey's fibers that, when combined with the vascularization, could help to provide insights into the growth of the structure. The 3D data of the scales from Lophosteus superbus is similar to comparable data from other fossil osteichthyans, and the morphology of the reconstructed buried odontodes from this species is identical to scale material of Lophosteus ohesaarensis, casting doubt on the validity of that species. The 3D data presented in this paper is the first for fossil fin spines and so comparable data is not yet available. However, the overall morphology and histology seems to be similar to the structure of placoderm dermal plates. The 3D datasets presented here provide show that microtomography is a powerful tool for investigating the three-dimensional microstructure of fossils, which is difficult to study using traditional histological methods. These results also increase the utility of fin spines and scales suggest that these data are a potentially rich source of morphological data that could be used for studying questions relating to early vertebrate growth and evolution.

  • 77.
    Jerve, Anna
    et al.
    Imperial Coll London, Biol Dept, Silwood Pk Campus, Ascot, Berks, England.
    Qu, Qinming
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Univ Ottawa, Ctr Adv Res Environm Genom, Ottawa, ON, Canada.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab. European Synchrotron Radiat Facil, Grenoble, France.
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Haitina, Tatjana
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Vascularization and odontode structure of a dorsal ridge spine of Romundina stellina Ørvig 19752017Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, nr 12, artikel-id e0189833Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There are two types of dermal skeletons in jawed vertebrates: placoderms and osteichthyans carry large bony plates (macromery), whereas chondrichthyans and acanthodians are covered by small scales (micromery). Fin spines are one of the last large dermal structures found on micromeric taxa and offer a potential source of histology and morphology that can be compared to those found on macromeric groups. Dermal fin spines offer a variety of morphology but aspects of their growth modes and homology are unclear. Here, we provide detailed descriptions of the microstructure and growth of a dorsal ridge spine from the acanthothoracid placoderm, Romundina stellina, using virtual three-dimensional paleohistological datasets. From these data we identify several layers of dentine ornamentation covering the lateral surfaces of the spine and reconstructed their growth pattern. We show that this spine likely grew posteriorly and proximally from a narrow portion of bone located along the leading edge of the spine. The spine is similarly constructed to the scales with a few exceptions, including the absence of polarized fibers distributed throughout the bone and the presence of a thin layer of perichondral bone. The composition of the spine (semidentine odontodes, dermal bone, perichondral bone) is identical to that of the Romundina dermal plates. These results illustrate the similarities and differences between the dermal tissues in Romundina and indicate that the spine grew differently from the dentinous fin spines from extant and fossil chondrichthyans. The morphology and histology of Romundina is most similar to the fin spine of the probable stem osteichthyan Lophosteus, with a well-developed inner cellular bony base and star-shaped odontodes on the surface. Results from these studies will undoubtedly have impact on our understanding of fossil fin spine histology and evolution, contributing to the on-going revision of early gnathostome phylogeny.

  • 78. Johanson, Zerina
    et al.
    Ahlberg, Per E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Phylogeny of lungfishes2010Ingår i: The Biology of Lungfishes / [ed] Jørgen Mørup Jørgensen, Jean Joss, Enfield, N.H.: Science Publishers , 2010, s. 43-60Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 79. Johanson, Zerina
    et al.
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Ritchie, Alex
    First record of Porolepis (Sarcopterygii; Porolepiformes) from eastern Gondwana2013Ingår i: Canadian journal of earth sciences (Print), ISSN 0008-4077, E-ISSN 1480-3313, Vol. 50, nr 3, s. 249-253Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Porolepiformes (Sarcopterygii) are poorly represented in the Devonian of Australia and eastern Gondwana as a whole. New cosmine-covered lower jaws from the Mulga Downs Group, western New South Wales (?Pragian-Emsian or Eifelian), represent the first occurrence of Porolepis in Australia, a genus formerly known exclusively from the Northern Hemisphere. This material is assigned to the new species Porolepis foxi. The wide distribution of Porolepis, demonstrated by its occurrence in New South Wales, Europe, and Spitsbergen, contrasts with the generally high endemicity of the faunas in which it is present.

  • 80. Johanson, Zerina
    et al.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för fysiologi och utvecklingsbiologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för fysiologi och utvecklingsbiologi, Evolutionär organismbiologi.
    Ritchie, Alex
    The braincase and palate of the tetrapodomorph sarcopterygian Mandageria fairfaxi: morphological variability near the fish-tetrapod transition.2003Ingår i: Palaeontology, ISSN 0031-0239, Vol. 46, s. 271-293Artikel i tidskrift (Refereegranskat)
  • 81.
    Kamska, Viktoriia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Daeschler, Edward B.
    Drexel Univ, Acad Nat Sci, 1900 Benjamin Franklin Pkwy, Philadelphia, PA 19103 USA.
    Downs, Jason P.
    Drexel Univ, Acad Nat Sci, 1900 Benjamin Franklin Pkwy, Philadelphia, PA 19103 USA;Delaware Valley Univ, Dept Biol, 700 East Butler Ave, Doylestown, PA 18901 USA.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Tafforeau, Paul
    European Synchrotron Radiat Facil, 71 Ave Martyrs, F-38000 Grenoble, France.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab. European Synchrotron Radiat Facil, 71 Ave Martyrs, F-38000 Grenoble, France;Univ Paris 06, Sorbonne Univ, Ctr Rech Paleobiodiversite & Paleoenvironm, Museum Natl Hist Nat,CNRS, 57 Rue Cuvier,CP38, F-75005 Paris, France.
    Long-bone development and life-history traits of the Devonian tristichopterid Hyneria lindae2019Ingår i: Earth and environmental science transactions of the Royal Society of Edinburgh, ISSN 1755-6910, E-ISSN 1755-6929, Vol. 109, nr 1-2, s. 75-86Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hyneria lindae is one of the largest Devonian sarcopterygians. It was found in the Catskill Formation (late Famennian) of Pennsylvania, USA. The current study focuses on the palaeohistology of the humerus of this tristichopterid and supports a low ossification rate and a late ossification onset in the appendicular skeleton. In addition to anatomical features, the large size of the cell lacunae in the cortical bone of the humerus mid-shaft may suggest a large genome size and associated neotenic condition for this species, which could, in turn, be a partial explanation for the large size of H. lindae. The low metabolism of H. lindae revealed here by bone histology supports the hypothesis of an ambush predatory behaviour. Finally, the lines-of-arrested-growth pattern and late ossification of specimen ANSP 21483 suggest that H. lindae probably had a long juvenile stage before reaching sexual maturity. Although very few studies address the life-history traits of stem tetrapods, they all propose a slow limb development for the studied taxa despite different ecological conditions and presumably distinct behaviours. The bone histology of H. lindae would favour the hypothesis that a slow long-bone development could be a general character for stem tetrapods.

  • 82. Khonsari, R. H.
    et al.
    Olivier, J.
    Vigneaux, P.
    Sanchez, S.
    Tafforeau, P.
    Ahlberg, Per E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Di Rocco, F.
    Bresch, D.
    Corre, P.
    Ohazama, A.
    Sharpe, P. T.
    Calvez, V.
    A mathematical model for mechanotransduction at the early steps of suture formation2013Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 280, nr 1759, s. 20122670-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Growth and patterning of craniofacial sutures is subjected to the effects of mechanical stress. Mechanotransduction processes occurring at the margins of the sutures are not precisely understood. Here, we propose a simple theoretical model based on the orientation of collagen fibres within the suture in response to local stress. We demonstrate that fibre alignment generates an instability leading to the emergence of interdigitations. We confirm the appearance of this instability both analytically and numerically. To support our model, we use histology and synchrotron X-ray microtomography and reveal the fine structure of fibres within the sutural mesenchyme and their insertion into the bone. Furthermore, using a mouse model with impaired mechanotransduction, we show that the architecture of sutures is disturbed when forces are not interpreted properly. Finally, by studying the structure of sutures in the mouse, the rat, an actinopterygian (Polypterus bichir) and a placoderm(Compagopiscis croucheri), we show that bone deposition patterns during dermal bone growth are conserved within jawed vertebrates. In total, these results support the role of mechanical constraints in the growth and patterning of craniofacial sutures, a process that was probably effective at the emergence of gnathostomes, and provide new directions for the understanding of normal and pathological suture fusion.

  • 83.
    Kundrát, Martin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Univ Pavol Jozef Safarik, Ctr Interdisciplinary Biosci Technol & Innovat Pk, Kosice, Slovakia.
    Nudds, John
    Univ Manchester, Sch Earth & Environm Sci, Manchester, Lancs, England.
    Kear, Benjamin P.
    Uppsala universitet, Enheten för musik och museer, Evolutionsmuseet.
    Lu, Junchang
    Chinese Acad Geol Sci, Key Lab Stratig & Paleontol, Inst Geol, Minist Land Resources, Beijing, Peoples R China.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    The first specimen of Archaeopteryx from the Upper Jurassic Mornsheim Formation of Germany2019Ingår i: Historical Biology, ISSN 0891-2963, E-ISSN 1029-2381, Vol. 31, nr 1, s. 3-63Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    From an initial isolated position as the oldest evolutionary prototype of a bird, Archaeopteryx has, as a result of recent fossil discoveries, become embedded in a rich phylogenetic context of both more and less crownward stem-group birds. This has prompted debate over whether Archaeopteryx is simply a convergently bird-like non-avialan theropod. Here we show, using the first synchrotron microtomographic examination of the genus, that the eighth or Daiting specimen of Archaeopteryx possesses a character suite that robustly constrains it as a basal avialan (primitive bird). The specimen, which comes from the Mornsheim Formation and is thus younger than the other specimens from the underlying Solnhofen Formation, is distinctive enough to merit designation as a new species, Archaeopteryx albersdoerferi sp. nov., but is recovered in close phylogenetic proximity to Archaeopteryx lithographica. Skeletal innovations of the Daiting specimen, such as fusion and pneumatization of the cranial bones, well vascularized pectoral girdle and wing elements, and a reinforced configuration of carpals and metacarpals, suggest that it may have had more characters seen in flying birds than the older Archaeopteryx lithographica. These innovations appear to be convergent on those of more crownward avialans, suggesting that Bavarian archaeopterygids independently acquired increasingly bird-like traits over time. Such mosaic evolution and iterative exploration of adaptive space may be typical for major functional transitions like the origin of flight.

  • 84.
    Kundrát, Martin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sotak, Ján
    Geological Institute, Slovak Academy of Sciences.
    Ahlberg, Per E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    A putative upupiform bird from the Early Oligocene of the Central Western Carpathians and a review of fossil birds unearthed in Slovakia2015Ingår i: Acta Zoologica (Stockholm), ISSN 0001-7272, E-ISSN 1463-6395, Vol. 96, nr 1, s. 45-59Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An isolated hind limb of a miniature bird from an Early Oligocene locality (30–34 Ma) near Bystre (Slovakia) is described and analyzed. The tarsometatarsus (TMT) of the specimen is remarkably short relative to the tibiotarsus. When relative length ratios of the bones are compared with a sample of 29 extant and extinct birds with short metatarsi, the specimen variably clusters with some alcedinids, coraciids and trochilids. Log-clusters give less ambiguous results and indicate significant proximity of the Bystre specimen to the extinct messelirrisorids (Upupiformes) and the recent alcedinids (Coraciiformes). With regard to morphological details, such as those of the first metatarsal, II-IV metatarsal trochleae, intertrochlear incisurae and phalanges, the Slovak specimen shows a combination of features, which are distributed among recent upupiforms and coraciiforms as well as extinct upupiforms (Messelirrisor) and apodiforms (Eocypselus, Parargornis). Taken together, the metric and morphological data sets suggest that the specimen from Bystre is a coraciiform sensu lato rather than an apodiform bird. Within the Coraciiformes, the robust trochlea of MT-I with expanded dorsal shelf, the large medial and slit-like lateral intertrochlear incisura, and the long hindtoe suggest upupiform rather than alcedinid relationships.

  • 85.
    Kuratani, Shigeru
    et al.
    RIKEN, Lab Evolutionary Morphol, Chuo Ku, 2-2-3 Minatojima Minami, Kobe, Hyogo 6500047, Japan..
    Ahlberg, Per E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Evolution of the vertebrate neurocranium: problems of the premandibular domain and the origin of the trabecula2018Ingår i: ZOOLOGICAL LETTERS, ISSN 2056-306X, Vol. 4, artikel-id 1Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The subdivision of the gnathostome neurocranium into an anterior neural crest-derived moiety and a posterior mesodermal moiety has attracted the interest of researchers for nearly two centuries. We present a synthetic scenario for the evolution of this structure, uniting developmental data from living cyclostomes and gnathostomes with morphological data from fossil stem gnathostomes in a common phylogenetic framework. Ancestrally, vertebrates had an anteroposteriorly short forebrain, and the neurocranium was essentially mesodermal; skeletal structures derived from premandibular ectomesenchyme were mostly anterior to the brain and formed part of the visceral arch skeleton. The evolution of a one-piece neurocranial 'head shield' in jawless stem gnathostomes, such as galeaspids and osteostracans, caused this mesenchyme to become incorporated into the neurocranium, but its position relative to the brain and nasohypophyseal duct remained unchanged. Basically similar distribution of the premandibular ectomesenchyme is inferred, even in placoderms, the earliest jawed vertebrates, in which the separation of hypophyseal and nasal placodes obliterated the nasohypophyseal duct, leading to redeployment of this ectomesenchyme between the separate placodes and permitting differentiation of the crown gnathostome trabecula that floored the forebrain. Initially this region was very short, and the bulk of the premandibular cranial part projected anteroventral to the nasal capsule, as in jawless stem gnathostomes. Due to the lengthening of the forebrain, the anteriorly projecting 'upper lip' was lost, resulting in the modern gnathostome neurocranium with a long forebrain cavity floored by the trabeculae.

  • 86.
    Lindgren, Johan
    et al.
    Lund Univ, Dept Geol, Lund, Sweden.
    Sjövall, Peter
    RISE Res Inst Sweden Chem & Mat, Boras, Sweden.
    Thiel, Volker
    Univ Gottingen, Geosci Ctr, Geobiol, Gottingen, Germany.
    Zheng, Wenxia
    North Carolina State Univ, Dept Biol Sci, Raleigh, NC 27695 USA.
    Ito, Shosuke
    Fujita Hlth Univ, Sch Hlth Sci, Dept Chem, Toyoake, Aichi, Japan.
    Wakamatsu, Kazumasa
    Fujita Hlth Univ, Sch Hlth Sci, Dept Chem, Toyoake, Aichi, Japan.
    Hauff, Rolf
    Urweltmuseum Hauff, Holzmaden, Germany.
    Kear, Benjamin P.
    Uppsala universitet, Enheten för musik och museer, Evolutionsmuseet.
    Engdahl, Anders
    Lund Univ, MAX Lab 4, Lund, Sweden.
    Alwmark, Carl
    Lund Univ, Dept Geol, Lund, Sweden.
    Eriksson, Mats E.
    Lund Univ, Dept Geol, Lund, Sweden.
    Jarenmark, Martin
    Lund Univ, Dept Geol, Lund, Sweden.
    Sachs, Sven
    Nat Kunde Museum Bielefeld, Abt Geowissensch, Bielefeld, Germany.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Marone, Federica
    Paul Scherrer Inst, Swiss Light Source, Villigen, Switzerland.
    Kuriyama, Takeo
    Univ Hyogo, Inst Nat & Environm Sci, Kobe, Hyogo, Japan;Wildlife Management Res Ctr, Tanba, Hyogo, Japan.
    Gustafsson, Ola
    Lund Univ, Dept Biol, Lund, Sweden.
    Malmberg, Per
    Chalmers Univ Technol, Dept Chem & Chem Engn, Gothenburg, Sweden.
    Thomen, Aurelien
    Univ Gothenburg, Dept Chem & Mol Biol, Gothenburg, Sweden.
    Rodriguez-Meizoso, Irene
    Lund Univ, Dept Chem, Ctr Anal & Synth, Lund, Sweden.
    Uvdal, Per
    Lund Univ, Dept Chem, Chem Phys, Lund, Sweden.
    Ojika, Makoto
    Nagoya Univ, Grad Sch Bioagr Sci, Dept Appl Biosci, Nagoya, Aichi, Japan.
    Schweitzer, Mary H.
    Lund Univ, Dept Geol, Lund, Sweden;North Carolina State Univ, Dept Biol Sci, Raleigh, NC 27695 USA;North Carolina Museum Nat Sci, Raleigh, NC USA.
    Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur2018Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 564, nr 7736, s. 359-365Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ichthyosaurs are extinct marine reptiles that display a notable external similarity to modern toothed whales. Here we show that this resemblance is more than skin deep. We apply a multidisciplinary experimental approach to characterize the cellular and molecular composition of integumental tissues in an exceptionally preserved specimen of the Early Jurassic ichthyosaur Stenopterygius. Our analyses recovered still-flexible remnants of the original scaleless skin, which comprises morphologically distinct epidermal and dermal layers. These are underlain by insulating blubber that would have augmented streamlining, buoyancy and homeothermy. Additionally, we identify endogenous proteinaceous and lipid constituents, together with keratinocytes and branched melanophores that contain eumelanin pigment. Distributional variation of melanophores across the body suggests countershading, possibly enhanced by physiological adjustments of colour to enable photoprotection, concealment and/or thermoregulation. Convergence of ichthyosaurs with extant marine amniotes thus extends to the ultrastructural and molecular levels, reflecting the omnipresent constraints of their shared adaptation to pelagic life.

  • 87.
    Long, John A.
    et al.
    Flinders University, Adelaide, South Australia.
    Mark-Kurik, Elga
    Tallinn University of Technology.
    Johanson, Zerina
    The Natural History Museum, London.
    Lee, Michael S.Y.
    South Australian Museum, Adelaide.
    Young, Gavin C.
    Australian National University, Canberra.
    Zhu, Min
    Institute of Vertebrate Palaeontology and Palaeoanthropology, Chinese Academy of Sciences, Beijing.
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Newman, Michael
    Jones, Roger
    den Blaauwen, Jan
    University of Amsterdam.
    Choo, Brian
    Flinders University, Adelaide.
    Trinajstic, Kate
    Curtin University, Perth, Western Australia.
    Copulation in antiarch placoderms and the origin of gnathostome internal fertilization2015Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 517, nr 7533, s. 196-199Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reproduction in jawed vertebrates (gnathostomes) involves either external or internal fertilization. It is commonly argued that internal fertilization can evolve from external, but not the reverse. Male copulatoryclaspers are present in certain placoderms, fossil jawed vertebrates retrieved as a paraphyletic segment of the gnathostome stem group in recent studies. This suggests that internal fertilization could be primitive for gnathostomes, but such a conclusion depends on demonstrating that copulation was not just a specialized feature of certain placoderm subgroups. The reproductive biology of antiarchs, consistently identified as the least crownward placoderms and thus of great interest in this context, has until now remained unknown. Here we show that certain antiarchs possessed dermal claspers in the males, while females bore paired dermal plates inferred to have facilitated copulation. These structures are not associated with pelvic fins. The clasper morphology resembles that of ptyctodonts, a more crownward placoderm group, suggesting that all placoderm claspers are homologous and that internal fertilization characterized all placoderms. This implies that external fertilization and spawning, which characterize most extant aquatic gnathostomes, must be derived from internal fertilization, even though this transformation has been thought implausible. Alternatively, the substantial morphological evidence for placoderm paraphyly must be rejected.

  • 88.
    Lu, Jing
    et al.
    Chinese Acad Sci, Inst Vertebrate Paleontol & Paleoanthropol, Key Lab Vertebrate Evolut & Human Origins, POB 643, Beijing 100044, Peoples R China..
    Zhu, Min
    Chinese Acad Sci, Inst Vertebrate Paleontol & Paleoanthropol, Key Lab Vertebrate Evolut & Human Origins, POB 643, Beijing 100044, Peoples R China..
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Qiao, Tuo
    Chinese Acad Sci, Inst Vertebrate Paleontol & Paleoanthropol, Key Lab Vertebrate Evolut & Human Origins, POB 643, Beijing 100044, Peoples R China..
    Zhu, You-an
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Chinese Acad Sci, Inst Vertebrate Paleontol & Paleoanthropol, Key Lab Vertebrate Evolut & Human Origins, POB 643, Beijing 100044, Peoples R China.
    Zhao, Wenjin
    Chinese Acad Sci, Inst Vertebrate Paleontol & Paleoanthropol, Key Lab Vertebrate Evolut & Human Origins, POB 643, Beijing 100044, Peoples R China..
    Jia, Liantao
    Chinese Acad Sci, Inst Vertebrate Paleontol & Paleoanthropol, Key Lab Vertebrate Evolut & Human Origins, POB 643, Beijing 100044, Peoples R China..
    A Devonian predatory fish provides insights into the early evolution of modern sarcopterygians2016Ingår i: SCIENCE ADVANCES, ISSN 2375-2548, Vol. 2, nr 6, artikel-id e1600154Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Crown or modern sarcopterygians (coelacanths, lungfishes, and tetrapods) differ substantially from stem sarcopterygians, such as Guiyu and Psarolepis, and a lack of transitional fossil taxa limits our understanding of the origin of the crown group. The Onychodontiformes, an enigmatic Devonian predatory fish group, seems to have characteristics of both stem and crown sarcopterygians but is difficult to place because of insufficient anatomical information. We describe the new skull material of Qingmenodus, a Pragian (similar to 409-million-year-old) onychodont from China, using high-resolution computed tomography to image internal structures of the braincase. In addition to its remarkable similarities with stem sarcopterygians in the ethmosphenoid portion, Qingmenodus exhibits coelacanth-like neurocranial features in the otic region. A phylogenetic analysis based on a revised data set unambiguously assigns onychodonts to crown sarcopterygians as stem coelacanths. Qingmenodus thus bridges the morphological gap between stem sarcopterygians and coelacanths and helps to illuminate the early evolution and diversification of crown sarcopterygians.

  • 89. Luksevics, Ervins
    et al.
    Ahlberg, Per E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Stinkulis, Girts
    Vasilkova, Jelena
    Zupins, Ivars
    Frasnian vertebrate taphonomy and sedimentology of macrofossil concentrations from the Langsede Cliff, Latvia2012Ingår i: Lethaia: an international journal of palaeontology and stratigraphy, ISSN 0024-1164, E-ISSN 1502-3931, Vol. 45, nr 3, s. 356-370Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The siliciclastic sequence of the Upper Devonian of Kurzeme, Western Latvia, is renowned for abundant vertebrate fossils, including the stem tetrapods Obruchevichthys gracilis and Ventastega curonica. During the first detailed taphonomic study of the vertebrate assemblage from the Ogre Formation cropping out at the Langsede Cliff, Imula River, abundant vertebrate remains have been examined and identified as belonging to one psammosteid, two acanthodian and three sarcopterygian genera; the placoderm Bothriolepis maxima dominates the assemblage. Besides fully disarticulated placoderm and psammosteid plates, separate sarcopterygian scales and teeth, and acanthodian spines, partly articulated specimens including complete distal segments of Bothriolepis pectoral fins, Bothriolepis head shields and sarcopterygian lower jaws have been found. The size distribution of the placoderm bones demonstrates that the individuals within the assemblage are of approximately uniform age. Distinct zones have been traced within the horizontal distribution of the bones. These linear zones are almost perpendicular to the dominant dip azimuth of the cross-beds and ripple-laminae and most probably correspond to the depressions between subaqueous dunes. Concavity ratio varies significantly within the excavation area. The degree of fragmentation of the bones and disarticulation of the skeletons suggest that the carcasses were reworked and slightly transported before burial. Sedimentological data suggest deposition in a shallow marine environment under the influence of rapid currents. The fossiliferous bed consists of a basal bone conglomerate covered by a cross-stratified sandstone with mud drapes, which is in turn overlain by ripple laminated sandstone, indicating the bones were buried by the gradual infilling of a tidal channel. All the MiddleUpper Devonian vertebrate bone-beds from Latvia are associated with sandy to clayey deposits and have been formed in a sea-coastal zone during rapid sedimentation episodes, but differ in fossil abundance and degree of preservation. 

  • 90. Matsuoka, Toshiyuki
    et al.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för fysiologi och utvecklingsbiologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för fysiologi och utvecklingsbiologi, Evolutionär organismbiologi. Evolutionär organismbiologi.
    Kessaris, Nicoletta
    Iannarelli, Palma
    Dennehy, Ulla
    Richardson, William
    McMahon, Andrew
    Koentges, Georgy
    Neural crest origins of the neck and shoulder.2005Ingår i: Nature, ISSN 0028-0836, Vol. 436, nr 7049, s. 347-355Artikel i tidskrift (Refereegranskat)
  • 91. Niedzwiedzki, Grzegorz
    et al.
    Szrek, Piotr
    Narkiewicz, Katarzyna
    Narkiewicz, Marek
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för fysiologi och utvecklingsbiologi, Evolution och utvecklingsbiologi.
    Tetrapod trackways from the early Middle Devonian period of Poland2010Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 463, nr 7277, s. 43-48Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The fossil record of the earliest tetrapods (vertebrates with limbs rather than paired fins) consists of body fossils and trackways. The earliest body fossils of tetrapods date to the Late Devonian period (late Frasnian stage) and are preceded by transitional elpistostegids such as Panderichthys and Tiktaalik that still have paired fins. Claims of tetrapod trackways predating these body fossils have remained controversial with regard to both age and the identity of the track makers. Here we present well-preserved and securely dated tetrapod tracks from Polish marine tidal flat sediments of early Middle Devonian (Eifelian stage) age that are approximately 18 million years older than the earliest tetrapod body fossils and 10 million years earlier than the oldest elpistostegids. They force a radical reassessment of the timing, ecology and environmental setting of the fish-tetrapod transition, as well as the completeness of the body fossil record.

  • 92.
    Novas, Fernando E.
    et al.
    Museo Argentino Ciencias Nat Bernardino Rivadavia, Lab Anat Comparada & Evoluc Vertebrados, Buenos Aires, DF, Argentina.
    Kundrát, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Agnolin, Federico L.
    Museo Argentino Ciencias Nat Bernardino Rivadavia, Lab Anat Comparada & Evoluc Vertebrados, Buenos Aires, DF, Argentina.; CEBBAD Univ Maimonides, Dept Ciencias Nat & Antropol, Fdn Hist Nat Felix de Azara, Buenos Aires, DF, Argentina.
    Ezcurra, Martín D.
    Univ Munich, GeoBioctr, D-80333 Munich, Germany.
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Isasi, Marcelo P.
    Museo Argentino Ciencias Nat Bernardino Rivadavia, Lab Anat Comparada & Evoluc Vertebrados, Buenos Aires, DF, Argentina.
    Arriagada, Alberto
    Lisandro de La Torre & Tamariscos, Gen Roca, Rio Negro, Argentina.
    Chafrat, Pablo
    Lisandro de La Torre & Tamariscos, Gen Roca, Rio Negro, Argentina.
    A new large pterosaur from the Late Cretaceous of Patagonia2012Ingår i: Journal of Vertebrate Paleontology, ISSN 0272-4634, E-ISSN 1937-2809, Vol. 32, nr 6, s. 1447-1452Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Here, we expand the meager record of Late Cretaceous South American pterosaurs with the description of a partial rostrum belonging to a large azhdarchid pterodactyloid. The specimen was collected close to the Bajo de Arriagada locality, corresponding to the uppermost Cretaceous Allen Formation of Argentina, around 80 km northwest of the well-sampled Bajo de Santa Rosa locality. The specimen represents the first unambiguous evidence of an azhdarchid pterosaur from South America. This specimen represents a new genus and species, Aerotitan sudamericanus, which is diagnosed based ona unique combination of characters, including one autapomorphy,and represents one of the largest known South Americanpterosaurs. The fossil here described resulted from a joint Argentine-Swedish paleontological expedition to Patagonia.

  • 93. Olive, Sebastien
    et al.
    Ahlberg, Per E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Pernègre, Vincent N.
    Poty, Edouard
    Steurbaut, Etienne
    Clément, Gael
    New discoveries of tetrapods (ichthyostegid-like and whatcheeriid-like) in the Famennian (Late Devonian) localities of Strud and Becco (Belgium)2016Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 59, nr 6, s. 827-840Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The origin of tetrapods is one of the key events in vertebrate history. The oldest tetrapod body fossils are Late Devonian (Frasnian–Famennian) in age, most of them consisting of rare isolated bone elements. Here we describe tetrapod remains from two Famennian localities from Belgium: Strud, in the Province of Namur, and Becco, in the Province of Liege. The newly collected material consists of an isolated complete postorbital, fragments of two maxillae, and one putative partial cleithrum, all from Strud, and an almost complete maxilla from Becco. The two incomplete maxillae and cleithrum from Strud, together with the lower jaw previously recorded from this site, closely resemble the genus Ichthyostega, initially described from East Greenland. The postorbital from Strud and the maxilla from Becco do not resemble the genus Ichthyostega. They show several derived anatomical characters allowing their tentative assignment to a whatcheeriid-grade group. The new tetrapod records show that there are at least two tetrapod taxa in Belgium and almost certainly two different tetrapod taxa at Strud. This locality joins the group of Devonian tetrapod bearing localities yielding more than one tetrapod taxon, confirming that environments favourable to early tetrapod life were often colonized by several tetrapod taxa.

  • 94.
    Pardo, Jason D.
    et al.
    Univ Calgary, Dept Comparat Biol & Expt Med, 3330 Hosp Dr, Calgary, AB T2N 4N1, Canada..
    Szostakiwskyj, Matt
    Univ Calgary, Dept Biol Sci, 2500 Univ Dr, Calgary, AB T2N 1N4, Canada..
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Anderson, Jason S.
    Univ Calgary, Dept Comparat Biol & Expt Med, 3330 Hosp Dr, Calgary, AB T2N 4N1, Canada..
    Hidden morphological diversity among early tetrapods2017Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 546, nr 7660, s. 642-645Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Phylogenetic analysis of early tetrapod evolution has resulted in a consensus across diverse data sets(1-3) in which the tetrapod stem group is a relatively homogenous collection of medium-to large-sized animals showing a progressive loss of 'fish' characters as they become increasingly terrestrial(4,5), whereas the crown group demonstrates marked morphological diversity and disparity(6). The oldest fossil attributed to the tetrapod crown group is the highly specialized astopod Lethiscus stocki(7,8), which shows a small size, extreme axial elongation, loss of limbs, spool-shaped vertebral centra, and a skull with reduced centres of ossification, in common with an otherwise disparate group of small animals known as lepospondyls. Here we use micro-computed tomography of the only known specimen of Lethiscus to provide new information that strongly challenges this consensus. Digital dissection reveals extremely primitive cranial morphology, including a spiracular notch, a large remnant of the notochord within the braincase, an open ventral cranial fissure, an anteriorly restricted parasphenoid element, and Meckelian ossifications. The braincase is elongate and lies atop a dorsally projecting septum of the parasphenoid bone, similar to stem tetrapods such as embolomeres. This morphology is consistent in a second astopod, Coloraderpeton, although the details differ. Phylogenetic analysis, including critical new braincase data, places astopods deep on the tetrapod stem, whereas another major lepospondyl lineage is displaced into the amniotes. These results show that stem group tetrapods were much more diverse in their body plans than previously thought. Our study requires a change in commonly used calibration dates for molecular analyses, and emphasizes the importance of character sampling for early tetrapod evolutionary relationships.

  • 95. Pierce, Stephanie E.
    et al.
    Ahlberg, Per E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Hutchinson, John R.
    Molnar, Julia L.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Tafforeau, Paul
    Clack, Jennifer A.
    Vertebral architecture in the earliest stem tetrapods2013Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 494, nr 7436, s. 226-229Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The construction of the vertebral column has been used as a key anatomical character in defining and diagnosing early tetrapod groups(1). Rhachitomous vertebrae(2)-in which there is a dorsally placed neural arch and spine, an anteroventially placed intercentrum and paired, posterodorsally placed pleurocentra have long been considered the ancestral morphology for tetrapods(1,3-6). Nonetheless, very little is known about vertebral anatomy in the earliest stem tetrapods, because most specimens remain trapped in surrounding matrix, obscuring Important anatomical features(7-9). Here we describe the three-dimensional vertebral architecture of the Late Devonian stem tetrapod Ichthyostega using propagation phase-contrast X-ray synchrotron. microtomography. Our scans reveal a diverse array of new morphological, and associated developmental and functional, characteristics, including a possible posterior-to-anterior vertebral ossification sequence and the first evolutionary appearance of ossified sternal elements. One of the most intriguing features relates to the positional relationships between the vertebral elements, with the pleurocentra being unexpectedly sutured or fused to the intercentra that directly succeed them, indicating a 'reverse' rhachitomous design(10). Comparison of Ichthyostega with two other stem tetrapods, Acanthostegi and Pederpess, shows that reverse rhachitomous vertebrae may be the ancestral condition for limbed vertebrates. This study fundamentally revises our current understanding' of vertebral column evolution in the earliest tetrapods and raises questions about the presumed vertebral architecture of tetrapodomorph fish(12,13) and later, more crownward, tetrapods.

  • 96.
    Qu, Qingming
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Blom, Henning
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    What is a pore-canal system?2011Ingår i: Abstracts: The 2nd Wiman meeting : Carl Wiman's Legacy : 100 years of Swedish Palaeontology : Uppsala 17–18 November 2011 / [ed] Benjamin P. Kear and Michael Streng, 2011, s. 20-21Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The pore-canal system is part of the defining ‘comsine’ structure of early sarcopterygians. It lies in the upper dentinous region of the dermal skeleton and has abundant external openings connected by horizontal ‘Maschenkanäle' to a deeper canal system in the thickened spongia layer – the ‘Unter-Maschenkanäle'. A similar horizontal canal system is also present in early actinopterygians but is not generally considered homologous. We generated 3D reconstructions of scale canals in three early osteichthyans: Lophosteus, Andreolepis, and Psarolepis, the latter being a basal sarcopterygian. Well-developed horizontal canal-systems were found in all of the sampled taxa, although their morphology was more regular in Psarolepis. In addition, Psarolepis possesses a less regular canal system at slightly deeper levels within the bony tissues, which might correspond to the ‘Unter-Maschenkanäle' of crown sarcopterygians (e.g. Porolepis). Conversely, the dentinal canals in Psarolepis appear to arise from both the lower canal system and horizontal ‘Maschenkanäle'. This feature represents a potential link between actinopterygians and sarcopterygians, thus rendering the horizontal canal system (probably part of the vascularization of the scale) potentially homologous across early osteichthyans.

  • 97.
    Qu, Qingming
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Ahlberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Blom, Henning
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Zhu, Min
    Li, Gang
    What is a pore-canal system?2011Ingår i: Program and Abstracts: 71st Annual Meeting Society of Vertebrate Paleontology, Philadelphia: Society of Vertebrate Paleontology , 2011, s. 177-177Konferensbidrag (Övrigt vetenskapligt)
  • 98.
    Qu, Qingming
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi.
    Haitina, Tatjana
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Zhu, Min
    Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences.
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    New genomic and fossil data illuminate the origin of enamel2015Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 526, nr 7571, s. 108-120Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Enamel, the hardest vertebrate tissue, covers the teeth of almost all sarcopterygians (lobe-finned bony fishes and tetrapods) as well as the scales and dermal bones of many fossil lobe-fins(1-5). Enamel deposition requires an organic matrix containing the unique enamel matrix proteins (EMPs) amelogenin (AMEL), enamelin (ENAM) and ameloblastin (AMBN)(6). Chondrichthyans (cartilaginous fishes) lack both enamel and EMP genes(7,8). Many fossil and a few living non-teleost actinopterygians (ray-finned bony fishes) such as the gar, Lepisosteus, have scales and dermal bones covered with a proposed enamel homologue called ganoine(1,9). However, no gene or transcript data for EMPs have been described from actinopterygians(10,11). Here we show that Psarolepis romeri, a bony fish from the the Early Devonian period, combines enamel-covered dermal odontodes on scales and skull bones with teeth of naked dentine, and that Lepisosteus oculatus (the spotted gar) has enam andambn genes that are expressed in the skin, probably associated with ganoine formation. The genetic evidence strengthens the hypothesis that ganoine is homologous with enamel. The fossil evidence, further supported by the Silurian bony fish Andreolepis, which has enamel-covered scales but teeth and odontodes on its dermal bones made of naked dentine(12-16), indicates that this tissue originated on the dermal skeleton, probably on the scales. It subsequently underwent heterotopic expansion across two highly conserved patterning boundaries (scales/head-shoulder and dermal/oral) within the odontode skeleton.

  • 99.
    Qu, Qingming
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Blom, Henning
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Tafforeau, Paul
    Ahlberg, Per Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Scales and Tooth Whorls of Ancient Fishes Challenge Distinction between External and Oral 'Teeth'2013Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, nr 8, s. e71890-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The debate about the origin of the vertebrate dentition has been given fresh fuel by new fossil discoveries and developmental studies of extant animals. Odontodes (teeth or tooth-like structures) can be found in two distinct regions, the 'internal' oropharyngeal cavity and the 'external' skin. A recent hypothesis argues that regularly patterned odontodes is a specific oropharyngeal feature, whereas odontodes in the external skeleton lack this organization. However, this argument relies on the skeletal system of modern chondrichthyans (sharks and their relatives), which differ from other gnathostome (jawed vertebrate) groups in not having dermal bones associated with the odontodes. Their external skeleton is also composed of monoodontode 'placoid scales', whereas the scales of most early fossil gnathostomes are polyodontode, i.e. constructed from several odontodes on a shared bony base. Propagation phase contrast X-ray Synchrotron microtomography (PPC-SRmCT) is used to study the polyodontode scales of the early bony fish Andreolepis hedei. The odontodes constructing a single scale are reconstructed in 3D, and a linear and regular growth mechanism similar to that in a gnathostome dentition is confirmed, together with a second, gap-filling growth mechanism. Acanthodian tooth whorls are described, which show that ossification of the whorl base preceded and probably patterned the development of the dental lamina, in contrast to the condition in sharks where the dental lamina develops early and patterns the dentition. The new findings reveal, for the first time, how polyodontode scales grow in 3D in an extinct bony fish. They show that dentition-like odontode patterning occurs on scales and that the primary patterning unit of a tooth whorl may be the bony base rather than the odontodes it carries. These results contradict the hypothesis that oropharyngeal and external odontode skeletons are fundamentally separate and suggest that the importance of dermal bone interactions to odontode patterning has been underestimated.

  • 100.
    Qu, Qingming
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Sanchez, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab. European Synchrotron Radiat Facil, 71 Ave Martyrs, F-38043 Grenoble 09, France.
    Zhu, Min
    Chinese Acad Sci, Inst Vertebrate Paleontol & Paleoanthropol, Key Lab Vertebrate Evolut & Human Origins, Xiwaidajie 142, Beijing 100044, Peoples R China.
    Blom, Henning
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi.
    Ahlberg, Per E
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Evolution och utvecklingsbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    The origin of novel features by changes in developmental mechanisms: ontogeny and three-dimensional microanatomy of polyodontode scales of two early osteichthyans2017Ingår i: Biological Reviews, ISSN 1464-7931, E-ISSN 1469-185X, Vol. 92, nr 2, s. 1189-1212Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recent advances in synchrotron imaging allow us to study the three-dimensional (3D) histology of vertebrate fossils, including microfossils (e.g. teeth and scales) of early jawed vertebrates. These microfossils can often be scanned at submicron resolution (<1 µm) because of their small size. The resulting voxel (3D pixel) stacks can be processed into virtual thin sections revealing almost every internal detail of the samples, comparable to traditional thin sections. In addition, 3D models of the internal microanatomical structures, such as embedded odontodes and vasculature, can be assembled and examined in situ. Scales of two early osteichthyans, Psarolepis romeri from the Early Devonian of China and Andreolepis hedei from the Late Silurian of Sweden, were scanned using propagation phase-contrast synchrotron X-ray microtomography (PPC-SRµCT), and 3D models of internal canal systems and buried odontodes were created from the scans. Based on these new data, we review the evolutionary origin of cosmine and its associated pore-canal system, which has been long recognized as a synapomorphy of sarcopterygians. The first odontode that appeared during growth shows almost identical morphology in the two scales, but the second odontode of the Psarolepis scale shows a distinctive morphology with several pores on the surface. It is suggested that a shift from ridge-like odontode to pore-bearing odontode was the key step in the origin of cosmine, which was then elaborated further in more-derived sarcopterygians. We perform a detailed comparison between the two scales and propose a primary homology framework to generate microanatomical characters, which can be used in the phylogenetic analysis of early osteichthyans when more 3D data become available. Our results highlight the importance of 3D data for the study of histology and ontogeny of the dermal skeleton of early jawed vertebrates, especially scales of the polyodontode type. The traditional microvertebrate collection is not only useful for biostratigraphic studies, but also preserves invaluable biological information about the growth of vertebrate hard tissues. Today, we are only beginning to understand the biological meaning of the new 3D data. The increasing availability of such data will enable, and indeed require, a complete revision of traditional palaeohistological studies on early vertebrates.

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