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  • 1.
    Bazzi, Mohamad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Kear, Benjamin P.
    Uppsala University, Music and Museums, Museum of Evolution.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Ahlberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Campione, Nicolas E.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Univ New England, Sch Environm & Rural Sci, Palaeosci Res Ctr, Armidale, NSW 2351, Australia.
    Static Dental Disparity and Morphological Turnover in Sharks across the End-Cretaceous Mass Extinction2018In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 28, no 16, p. 2607-2615Article in journal (Refereed)
    Abstract [en]

    The Cretaceous-Palaeogene (K-Pg) mass extinction profoundly altered vertebrate ecosystems and prompted the radiation of many extant clades [1, 2]. Sharks (Selachimorpha) were one of the few larger-bodied marine predators that survived the K-Pg event and are represented by an almost-continuous dental fossil record. However, the precise dynamics of their transition through this interval remain uncertain [3]. Here, we apply 2D geometric morphometrics to reconstruct global and regional dental morphospace variation among Lamniformes (Mackerel sharks) and Carch-arhiniformes (Ground sharks). These clades are prevalent predators in today's oceans, and were geographically widespread during the late Cretaceous-early Palaeogene. Our results reveal a decoupling of morphological disparity and taxonomic richness. Indeed, shark disparity was nearly static across the K-Pg extinction, in contrast to abrupt declines among other higher-trophic-level marine predators [4, 5]. Nevertheless, specific patterns indicate that an asymmetric extinction occurred among lamniforms possessing lowcrowned/triangular teeth and that a subsequent proliferation of carcharhiniforms with similar tooth morphologies took place during the early Paleocene. This compositional shift in post-Mesozoic shark lineages hints at a profound and persistent K-Pg signature evident in the heterogeneity of modern shark communities. Moreover, such wholesale lineage turnover coincided with the loss of many cephalopod [6] and pelagic amniote [5] groups, as well as the explosive radiation of middle trophic-level teleost fishes [1]. We hypothesize that a combination of prey availability and post-extinction trophic cascades favored extant shark antecedents and laid the foundation for their extensive diversification later in the Cenozoic [7-10].

  • 2. Blieck, A.
    et al.
    Clément, G.
    Blom, Henning
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    Lelièvre, H.
    Luksevics, E.
    Streel, M.
    Thorez, J.
    Young, G. C.
    The biostratigraphical and palaeogeographical framework of the earliest diversification of tetrapods (Late Devonian)2007In: Devonian Events and Correlations - SDS volume in honour of M. House, 2007, p. 219-235Chapter in book (Refereed)
  • 3.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology.
    A new anaspid fish from the middle Silurian Cowie Harbour fish bed of Stonehaven, Scotland 2008In: Journal of Vertebrate Paleontology, ISSN 0272-4634, E-ISSN 1937-2809, Vol. 28, no 3, p. 594-600Article in journal (Refereed)
    Abstract [en]

    A new birkeniid anaspid, Cowielepis ritchiei gen. et sp. nov., from the mid Silurian Cowie Harbour fish bed in Scotland is described on the basis of three specimens. Although sharing characters with various well-known anaspids, it possesses a unique combination of features that justifies the establishment of a new genus. Cowielepis is characterized by a single row of dorsolateral scales and a distinctive skull roof pattern with a large pineal plate and elongated posterior plates. The presence of paired ventrolateral fins in C. ritchiei supports previous suggestions that all anaspids possess such fins, but leaves open the question of homology with the gnathostome pectoral fin.

  • 4.
    Blom, Henning
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    Anaspida2007In: McGraw-Hill Encyclopedia of Science and Technology, 10th Edition, 2007, p. 651-Chapter in book (Other (popular scientific, debate etc.))
  • 5.
    Blom, Henning
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    Interrelationships and evolutionary history of the anaspid fishes.2005In: Journal of Vertebrate Paleontology, ISSN 0272-4634, Vol. 25, no 3, p. 28A-Article in journal (Refereed)
  • 6.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology.
    Loganellia (Thelodonti, Agnatha) from the Lower Silurian of North Greenland, with special reference on their stratigraphical and paleogeographical significance1999In: Acta geologica Polonica, ISSN 0001-5709, E-ISSN 2300-1887, Vol. 49, no 2, p. 97-104Article in journal (Refereed)
    Abstract [en]

    Isolated thelodont scales from several Lower Silurian samples from North Greenland are re-described and compared with European forms, to assess their taxonomical, stratigraphical and palaeogeographical significance. Loganellia scotica s. s. (TRAQUAIR, 1898) scales, described from the Lafayette Bugt Formation, are more restricted than commonly supposed, being found only in Scotland and North Greenland. Reassignment of some thelodont scales from L. scotica to L. grossi (FREDHOLM, 1990) suggests a middle Wenlock age for the Kap Morton Formation.

  • 7.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    New birkeniid anaspid from the Lower Devonian of Scotland and its phylogenetic implications2012In: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 55, no 3, p. 641-652Article in journal (Refereed)
    Abstract [en]

    Abstract:  A new possible stem gnathostome, Kerreralepis carinata gen. et sp. nov., is described on the basis of a single specimen from the Lower Devonian of the island of Kerrera in the Inner Hebrides, Scotland. It is recognized as an anaspid by the chevron-like arranged rod-shaped scales on the trunk, gill openings extending behind the orbits in a slanting row and a series of median dorsal ridge scales. This specimen also has a series of median ventral plates, indicating the presence of a preanal fin-fold, which in turn has consequences for interpretations of other problematic stem gnathostomes and their phylogenetic context. A cladistic analysis supports a monophyletic Anaspida including the scale-covered birkeniids but excluding Lasanius as well as anaspid-like forms such as Euphanerops and Jamoytius. The establishment of a new genus and species increases the diversity of anaspids and allows for a more detailed study of anaspid interrelationships. An ingroup analysis using Lasanius as an outgroup resolves Birkenia as a rather basal anaspid, sister to all other anaspids, alternatively sister to a clade represented by the taxa from Ringerike, Norway, and the closely associated taxon from Saaremaa Island, Estonia. These topologies agree rather well with the present fossil record of anaspids.

  • 8.
    Blom, Henning
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Earth Sciences, Department of Earth Sciences.
    Silurian vertebrates from North Greenland2000Chapter in book (Refereed)
  • 9.
    Blom, Henning
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    Taxonomic revision of the Late Devonian tetrapod Ichthyostega from East Greenland.2005In: Palaeontology, ISSN 0031-0239, Vol. 48, no 1, p. 111-134Article in journal (Refereed)
  • 10.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology. Evolutioänr organismbiologi.
    Vertebrate remains from Upper Silurian: Lower Devonian beds of Hall Land, North Greenland1999In: Geology of Greenland Survey Bulletin, ISSN 1397-1905, Vol. 182, p. 80p. 1-80Article in journal (Refereed)
    Abstract [en]

    Vertebrate microscopic remains of twenty-six taxa of thelodonts, heterostracans, osteostracans, anaspids, acanthodians and chondrichthyans are described from limestone beds in two localities of Late Silurian – Early Devonian age of the Chester Bjerg Formation, Hall Land, North Greenland. The limestone beds form a minor part of a monotonous calcareous sandstone– siltstone–mudstone sequence at the top of the Franklinian Basin succession. Stratigraphical recognition using several thelodont and acanthodian taxa, supported by regional geological and structural trends, suggests a Silurian–Devonian boundary interval between beds of the Halls Grav and Monument localities. This possible resolution of the previous problematic correlation between the two distant sections of monotonous nature demonstrates the potential biostratigraphic utility of thelodonts in Silurian–Devonian marine successions. The Chester Bjerg Formation thelodont assemblage is unique with several new endemic taxa, but Loganellia cf. L. tuvaensis is very similar to the type material of the Tuva region south of Siberia, Russia and indicates a Late Silurian age for the beds of the Halls Grav locality. Canonia cf. C. grossi suggests an Early Devonian age for the Monument locality, since Canonia is so far only found in Lower Devonian marine strata of Arctic Canada and Russia. Fragments of cosmopolitan acanthodian genera such as Poracanthodes, Gomphonchus and Nostolepis are found together with heterostracans, osteostracans, anaspids and chondrichthyans at both localities but do not give a more exact age determination than Late Silurian – Early Devonian. New thelodont taxa are Loganellia almgreeni sp. nov., Paralogania foliala sp. nov., Praetrilogania grabion gen. et sp. nov. and Thulolepis striaspina gen. et sp. nov. Nostolepis halli sp. nov. is a new acanthodian species.

  • 11.
    Blom, Henning
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    Ahlberg, Per
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    Clack, Jennifer
    The postcranial skeleton of the Devonian tetrapod Ichthyostega from East Greenland.2005In: GFF, ISSN 1103-5897, Vol. 127, p. 45-Article in journal (Other scientific)
  • 12.
    Blom, Henning
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    Brazeau, MartinUppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    40th Anniversary Symposium on Early Vertebrates/Lower Vertebrates Uppsala, Sweden, August 13-16, 20072007Conference proceedings (editor) (Refereed)
  • 13.
    Blom, Henning
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Evolutionär organsimbiologi.
    Carlsson, Anders
    Marshall, John, E.
    Vertebrate microremains from the Upper Devonian of East Greenland with comments on the Frasnian-Famennian boundary2006In: Bulletin of the Geological Society of Denmark, Vol. 53, no 39-46Article in journal (Refereed)
  • 14.
    Blom, Henning
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology.
    Clack, Jennifer A.
    Ahlberg, Per Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology.
    Friedman, Matt
    Devonian vertebrates from East Greenland: a review of faunal composition and distribution2007In: Geodiversitas, ISSN 1280-9659, E-ISSN 1638-9395, Vol. 29, no 1, p. 119-141Article, review/survey (Refereed)
    Abstract [en]

    The Devonian vertebrate faunas of East Greenland are reviewed and their distribution discussed for the first time in the light of the most recently published stratigraphical framework for the area. The predominantly Middle and Upper Devonian continental sediments have yielded representatives of most major groups of early fossil vertebrates, including heterostracans, placoderms, acanthodians, chondrichthyans, actinopterygians, lungfishes, porolepiforms, "osteolepiforms" and tetrapods, but to date, no single publication has treated them all in their stratigraphical context. We therefore attempt to place them into the most recent, formalised lithostratigraphy, providing improved resolution for their stratigraphical distribution, as a basis for comparing East Greenland with other Devonian faunal successions worldwide. The review highlights the fact that many problems of stratigraphical correlation and dating of the East Greenland Devonian deposits remain to be resolved by further fieldwork. Several assemblages ranging from Givetian to Famennian in age can be distinguished, that correspond to older superceded subdivisional nomenclature. A possible Frasnian fauna has been recognised for the first time, adding details to an otherwise poorly dated part of the succession. Typical Devonian taxa such as Holoptychius Agassiz, 1839 and Groenlandaspis Heintz, 1932 have apparently been recorded in an otherwise unique position above the Devonian-Carboniferous boundary in the upper part of the succession. New specimens of rare elements of the fauna including an unknown arthrodire placoderm, a putative chondrichthyan spine and a patch of possibly regurgitated acanthodian spines, are illustrated for the first time.

  • 15.
    Blom, Henning
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    Clack, Jennifer
    Ahlberg, Per
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology.
    Localities, distribution and stratigraphical context of the Late Devonian tetrapods of East Greenland.2005In: Meddelelser of Grönland, Geoscience, ISSN 0106-1046, Vol. 43, no 1, p. 4-50Article in journal (Refereed)
  • 16.
    Blom, Henning
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Jerve, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Qu, Qingming
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Chen, Donglei
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Märss, Tiiu
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology.
    Dupret, Vincent
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Sanchez, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology.
    Ahlberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    The affinity of Lophosteus and the evolution of osteichthyan characters2011Conference paper (Other academic)
  • 17.
    Blom, Henning
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Jerve, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Qu, Qinming
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Chen, Dong Lei
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Märss, Tiiu
    Tallinn University of Technology.
    Dupret, Vincent
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Sanchez, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Ahlberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    The affinity of Lophosteus  and the evolution of osteichthyan characters2011Conference paper (Refereed)
  • 18.
    Blom, Henning
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Evolutionär organismbiologi.
    Miller, C. G.
    Märss, T.
    A new birkeniid anaspid from the Upper Silurian of Skåne, south Sweden2003In: GFF, Vol. 125, p. 57-61Article in journal (Refereed)
  • 19.
    Blom, Henning
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology. Evolutionär organismbiologi. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology.
    Märss, T.
    Miller, C. G.
    Silurian and earliest Devonian Birkeniid anaspids from the northern Hemisphere2001In: Transactions of the Royal Society of Edinburgh. Earth sciences, ISSN 0263-5933, E-ISSN 1473-7116, Vol. 92, no 3, p. 263-323Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    The sculpture of scales and plates of articulated anaspids from the order Birkeniida is described and used to clarify the position of scale taxa previously left in open nomenclature. The dermal skeleton of a well-preserved squamation of Birkenia elegans Traquair, 1898 from the Silurian of Scotland shows a characteristic finely tuberculated sculpture over the whole body. Rhyncholepis parvula Kiær, 1911, Pterygolepis nitida (Kiær, 1911) and Pharyngolepis oblonga Kiær, 1911, from the Silurian of Norway show three other sculpture types. Northern Hemisphere disarticulated scales and plates are described here, supporting a new anaspid taxonomy that includes both articulated and disarticulated material. The diversity, distribution, evolutionary trends and biostratigraphy of anaspids are described in the context of this new taxonomy, which includes six families (two are new) subdivided into 16 genera (10 are new) and 22 species (15 are new).

    New taxa among Birkeniidae Traquair, 1898 are Birkenia robusta sp. nov. and Hoburgilepis papillata gen. et sp. nov.. Rhyncholepididae Kiær, 1924 includes Rhyncholepis butriangula sp. nov., Silmalepis erinacea gen. et sp. nov., Vesikulepis funiforma gen. et sp. nov., Maurylepis lacrimans gen. et sp. nov., and the previously described Schidiosteus mustelensis Pander, 1856 and Rytidolepis quenstedtii Pander, 1856. Tahulalepididae fam. nov. is represented by Tahulalepis elongituberculata gen. et sp. nov. and the revised T. kingi (Woodward, 1947). Septentrioniidae fam. nov. contains Septentrionia lancifera gen. et sp. nov., S. mucronata gen. et sp. nov., S. dissimilis gen. et sp. nov., S. seducta gen. et sp. nov., Liivilepis curvata gen. et sp. nov., Spokoinolepis alternans gen. et sp. nov. and Manbrookia asperella gen. et sp. nov. The family level position of Ruhnulepis longicostata gen. et sp. nov. is uncertain. Pterygolepididae Obruchev, 1964 and Pharyngolepididae Kiær, 1924 remain monogeneric.

  • 20.
    Blom, Henning
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    Snitting, Daniel
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    40th Anniversary Symposium on Early Vertebrates/Lower Vertebrates Uppsala, Sweden. Post-conference field trip 17-20 August 2007 - Silurian of Gotland - Guidebook2007Other (Other (popular scientific, debate etc.))
  • 21.
    Blom, Henning
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Zigaite, Zivile
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology.
    New thelodont findings from the Lower Devonian Andrée Land Group, Spitsbergen, and their implications for biostratigraphy2012Conference paper (Other academic)
  • 22.
    Bremer, Oskar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    An updated stratigraphic and environmental framework for the distribution of Silurian vertebrates on Gotland2015In: Estonian journal of earth sciences, ISSN 1736-4728, E-ISSN 1736-7557, Vol. 64, no 1, p. 13-18Article in journal (Refereed)
  • 23.
    Bremer, Oskar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Biostratigraphy of early vertebrates on Gotland2014In: 4th Annual Meeting of IGCP 591, Estonia, 10 - 19 June 2014.: Abstracts and Field Guide / [ed] Heikki Bauert, Olle Hints, Tõnu Meidla & Peep Männik, Tartu: University of Tartu, 2014, p. 21-21Conference paper (Other academic)
  • 24.
    Bremer, Oskar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Niedzwiedzki, Grzegorz
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Dec, Marek
    Polish Acad Sci, Inst Paleobiol, Twarda 51-55, PL-00818 Warsaw, Poland.
    Kozłowski, Wojciech
    Univ Warsaw, Inst Geol, Zwirki & Wigury 93, PL-02089 Warsaw, Poland.
    Vertebrate microremains from the upper Silurian Winnica Formation of the Holy Cross Mountains, Poland2018In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 155, no 7, p. 1523-1541Article in journal (Refereed)
    Abstract [en]

    Vertebrate microremains from the upper Silurian Winnica Formation in the Holy Cross Mountains, Poland are described from the Winnica and Rzepin sections. Both sites record the uppermost part of the Supianka Member, but represent different depositional environments. The Winnica samples come from a low-energy environment, while the Rzepin sample was taken from a high-energy, oolitic facies. Both sites contain thelodonts Thelodus parvidens, Thelodus trilobatus, an anaspid cf. Liivilepis and a number of acanthodian scales of 'nostolepid', poracanthodid and 'gomphonchid' types. Notable differences between the sites are the addition of the osteostracan Tahulaspis cf. ordinata, the thelodont Paralogania ludlowiensis and acanthodian scales identified as Nostolepis gracilis in the Rzepin section. Placing the vertebrate faunas within the vertebrate biozonation established for the Silurian proved difficult. The suggested late Ludlow age for the Supianka Member based on sequence stratigraphical and chemostratigraphical correlations cannot be definitely confirmed or refuted, but a late Ludfordian age seems the most plausible based on invertebrate and vertebrate faunas. The much lower abundance of poracanthodid acanthodians in the Rzepin sample supports the notion of Poracanthodes porosus Zone as a deep-water equivalent to a number of vertebrate biozones. The presence of P. ludlowiensis only in the oolitic sample confirms a long temporal range, but restricted environmental distribution for this taxon.

  • 25.
    Bremer, Oskar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Niedźwiedzki, Grzegorz
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Dec, Marek
    Kozłowski, Wojciech
    Vertebrate microremains from the upper Silurian Winnica Formation of the Holy Cross Mountains, Poland2017Conference paper (Other academic)
  • 26. Carlsson, Anders
    et al.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology.
    A new scolenaspidid (Osteostraci) from the lower Devonian of Podolia, Ukraine2008In: Paläontologische Zeitschrift, ISSN 0031-0220, Vol. 82, no 3, p. 314-323Article in journal (Refereed)
    Abstract [en]

    A new osteostracan genus and species. Victoraspis longicornualis n. gen., n. sp., is described based on material from Rakovets', present day Ukraine. This new taxon shares characters with the two genera Stensiopelta DENISON, 1951 and Zychaspis JANVIER, 1985. A phylogenetic analysis supports the position of Victoraspis as the sister group to a monophyletic Stensiopelta, while the interrelationships of the various species of Zychaspis are poorly resolved. A morphometric analysis is carried out in an attempt to further resolve the taxonomic affinity. This analysis groups all examined Zychaspis species closely together, and further supports the establishment of Victoraspis as separate, genus.

  • 27.
    Chen, Dong Lei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Alavi, Yasaman
    Univ Melbourne, Sch BioSci, Australia.
    Brazeau, Martin D.
    Imperial Coll London, Dept Life Sci, Berks, England.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Millward, David
    British Geol Survey, Lyell Ctr, Edinburgh, Midlothian, Scotland.
    Ahlberg, Per E.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    A partial lower jaw of a tetrapod from "Romer's Gap"2018In: Earth and environmental science transactions of the Royal Society of Edinburgh, ISSN 1755-6910, E-ISSN 1755-6929, Vol. 108, no 1, p. 55-65Article in journal (Refereed)
    Abstract [en]

    The first half of the Mississippian or Early Carboniferous (Tournaisian to mid-Visean), an interval of about 20 million years, has become known as "Romer's Gap" because of its poor tetrapod record. Recent discoveries emphasise the differences between pre-"Gap" Devonian tetrapods, unambiguous stem-group members retaining numerous "fish" characters indicative of an at least partially aquatic lifestyle, and post-"Gap" Carboniferous tetrapods, which are far more diverse and include fully terrestrial representatives of the main crown-group lineages. It seems that "Romer's Gap" coincided with the cladogenetic events leading to the origin of the tetrapod crown group. Here, we describe a partial right lower jaw ramus of a tetrapod from the late Tournaisian or early Visean of Scotland. The large and robust jaw displays a distinctive character combination, including a significant mesial lamina of the strongly sculptured angular, an open sulcus for the mandibular lateral line, a non-ossified narrow Meckelian exposure, a well-defined dorsal longitudinal denticle ridge on the prearticular, and a mesially open adductor fossa. A phylogenctic analysis places this specimen in a trichotomy with Crassigyrinus and baphetids + higher tetrapods in the upper part of the tetrapod stem group, above Whatcheeria, Pederpes, Ossinodus, Sigournea and Greererpeton. It represents a small but significant step in the gradual closure of "Romer's Gap".

  • 28.
    Chen, Dong Lei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Sanchez, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Tafforeau, Paul
    Estonian Marine Institute, University of Tartu.
    Märss, Tiiu
    Estonian Marine Institute, University of Tartu.
    Ahlberg, Per E.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Development of cyclic shedding teeth from semi-shedding teeth: the inner dental arcade of the stem osteichthyan Lophosteus 2017In: Royal Society Open Science, E-ISSN 2054-5703, Vol. 4, no 5, article id 161084Article in journal (Refereed)
    Abstract [en]

    The numerous cushion-shaped tooth-bearing plates attributed to the stem-group osteichthyan Lophosteus superbus, which are argued here to represent the ancient form of inner dental arcade, display a unique and presumably primitive way of tooth shedding by basal hard tissue resorption. They carry regularly spaced, recumbent, gently recurved teeth arranged in transverse tooth files that diverge towards the lingual margin of the cushion. Three-dimensional (3D) reconstruction from propagation phase contrast synchrotron microtomography (PPC-SRμCT) reveals remnants of the first-generation teeth embedded in the basal plate that have never been discerned in any taxa. These teeth were shed by semi-basal resorption with the periphery of their bases retained as dentine rings. The rings are highly overlapped, which evidences tooth shedding prior to adding the next first-generation tooth. Later teeth at the same sites underwent cyclical replacing and shedding through basal resorption, producing stacks of buried resorption surfaces separated by bone of attachment. The number and spatial arrangement of resorption surfaces elucidates that basal resorption of replacement teeth had taken place at the older tooth sites before the addition of the youngest first-generation teeth at the lingual margin. Thus the replacement tooth buds cannot have been generated by a single permanent dental lamina, but must have arisen either from successional dental laminae associated with the predecessor teeth, or directly from the dental epithelium of these teeth. The virtual histological dissection of these Late Silurian microfossils broadens our understanding of the development of the gnathostome dental systems and the acquisition of the osteichthyan-type of tooth replacement. 

  • 29.
    Chen, Donglei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Ahlberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Sanchez, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Dental Development of the Stem Osteichthyan Andreolepis hedei Revealed by Three-dimensional Synchrotron Virtual Paleohistology2013In: Program and Abstracts: Society of Vertebrate Paleontology 73rd Annual meeting, 2013, p. 103-103Conference paper (Other academic)
  • 30.
    Chen, Donglei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Ahlberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Sanchez, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Dental Development of the Stem Osteichthyan Andreolepis hedei Revealed by Three-dimensional Synchrotron Virtual Paleohistology2013Conference paper (Other academic)
  • 31.
    Chen, Donglei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Scale morphology and squamation of Andreolepis from the Late Silurian of Gotland, Sweden2011In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 133, no 1-2, p. 60-61p. 60-61Article in journal (Refereed)
  • 32.
    Chen, Donglei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Ahlberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Three-dimensional histology of tooth cushions of Lophosteus from the Late Silurian of Estonia2011In: Program and Abstracts: 71st Annual Meeting, Society of Vertebrate Paleontolog, Philadelphia: Society of Vertebrate Paleontology , 2011, p. 87-87Conference paper (Other academic)
  • 33.
    Chen, Donglei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Ahlberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Sanchez, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Three-dimensional histology of tooth cushions of Lophosteus from the Upper Silurian of Estonia2011In: 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, p. 5-6Conference paper (Other academic)
    Abstract [en]

    Lophosteus superbus from the Late Silurian of Estonia is one of the oldest and most plesiomorphic osteichthyans described to date. Unfortunately at present it is known only from fragmented dermal microremains. The affinities of Lophosteus are therefore controversial with the taxon placed as either basal to both actinopterygians and sarcopterygians, or ambiguously linked to either placoderms or acanthodians. To confound matters further, the character states diagnosing actinopterygians and sarcopterygians have recently been brought into question, and even monophyly of the traditional placoderm and acanthodian clades has been challenged. As a possible stem osteichthyan, Lophosteus could thus be central to our understanding of early gnathostome evolution and the origin of the osteichthyan body plan. Often the best-preserved, although incompletely documented, elements of Lophosteus are tooth cushions. These tooth-bearing arched ossicles could arguably be homologous with the parasymphysial tooth whorls in chondrichthyans, acanthodians, and sarcopterygians, or even the parasymphysial tooth plates in tetrapodomorphs. High-resolution synchrotron scans of 6 isolated tooth cushions from the Upper Silurian of Estonia has permitted a detailed reconstruction of their three-dimensional architecture. The absence of an enamel layer and the presence of large hollows (bigger than normal osteocytes) in the deepest lamellar layer confirmed assignment of the specimens to Lophosteus. The external surface displays irregularly distributed denticles and there are large parallel vessels running horizontally on the basal bone that feed the denticle rows internally. The odontodes have two distinct generations (with successive odontodes accreted between those of the preceding buried generation) and are organised in a similar manner to those found on Lophosteus scales. This new histological data on vascularization provides insight into early gnathostome tooth patterning and could contribute to future phylogenetic assessments.

  • 34.
    Chen, Donglei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Sanchez, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology. Uppsala University, Science for Life Laboratory, SciLifeLab. European Synchrotron Radiat Facil, 6 Rue Jules Horowitz, F-38043 Grenoble, France..
    Tafforeau, Paul
    European Synchrotron Radiat Facil, 6 Rue Jules Horowitz, F-38043 Grenoble, France..
    Ahlberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    The stem osteichthyan Andreolepis and the origin of tooth replacement2016In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 539, no 7628, p. 237-+Article in journal (Refereed)
    Abstract [en]

    The teeth of gnathostomes (jawed vertebrates) show rigidly patterned, unidirectional replacement that may or may not be associated with a shedding mechanism. These mechanisms, which are critical for the maintenance of the dentition, are incongruently distributed among extant gnathostomes. Although a permanent tooth-generating dental lamina is present in all chondrichthyans, many tetrapods and some teleosts, it is absent in the non-teleost actinopterygians. Tooth-shedding by basal hard tissue resorption occurs in most osteichthyans (including tetrapods) but not in chondrichthyans. Here we report a three-dimensional virtual dissection of the dentition of a 424-million-year-old stem osteichthyan, Andreolepis hedei, using propagation phase-contrast synchrotron microtomography, with a reconstruction of its growth history. Andreolepis, close to the common ancestor of all extant osteichthyans, shed its teeth by basal resorption but probably lacked a permanent dental lamina. This is the earliest documented instance of resorptive tooth shedding and may represent the primitive osteichthyan mode of tooth replacement.

  • 35.
    Chen, Donglei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Janvier, Philippe
    Département Histoire de la Terre, Muséum National d'Histoire Naturelle,.
    Ahlberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Scale morphology and squamation of the Late Silurian osteichthyan Andreolepis from Gotland, Sweden2012In: Historical Biology, ISSN 0891-2963, E-ISSN 1029-2381, Vol. 24, no 4, p. 411-423Article in journal (Refereed)
    Abstract [en]

    The origin of osteichthyans (bony fishes and tetrapods) dates back to the Late Silurian, but the early evolution of the group is poorly understood. Andreolepis is one of the oldest known osteichthyans, but exclusively documented by detached and fragmentary dermal microremains. A large data-set of Andreolepis scales from the Silurian of Gotland has been used to explore the scale morphology on different parts of the body. Landmark-based geometric morphometrics together with comparative anatomy and functional morphology has allowed 10 morphotypes to be identified and incorporated into a squamation model, in which scales are allocated to anterior-mid lateral flank scales, posterior lateral flank scales, caudal peduncle scales, pectoral peduncle scales, dorsal flank scales, dorsal fulcral scales, caudal fulcral scales, ventral flank scales, medioventral scales and cranial scales. The scale morphology and squamation pattern ofAndreolepis may be primitive for the Osteichthyes and thus informative about the acquisition of the osteichthyan body plan.

  • 36. Clack, Jennifer A.
    et al.
    Ahlberg, Per E.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Finney, Sarah M.
    A new genus of Devonian tetrapod from North-East Greenland, with new information on the lower jaw of Ichthyostega2012In: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 55, no 1, p. 73-86Article in journal (Refereed)
    Abstract [en]

    A new genus and species of Devonian tetrapod has been identified from material collected in 1947 from the southern slope of Mt. Celsius, Ymer phi, North-East Greenland. The specimen preserves both lower jaws, partial palate, premaxillae and maxillae, with a natural mould of parts of the shoulder girdle. The new taxon, Ymeria denticulata, shows differences in dentition, skull ornament and lateral line expression from both Acanthostega and Ichthyostega, but it shows a closer resemblance to the latter. A cladistic analysis not only suggests that Ymeria lies adjacent to Ichthyostega on the tetrapod stem, but also reveals substantial topological instability. As the third genus and the fifth species of tetrapod identified from North-East Greenland, it demonstrates the high diversity of Devonian tetrapods in that region.

  • 37. Clack, Jennifer
    et al.
    Ahlberg, Per
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    Blom, Henning
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    New insights into the postcranial skeleton of Ichthyostega.2003In: Journal of Vertebrate Paleontology, ISSN 0272-4634, Vol. 23, no 3(supplement), p. 41A-Article in journal (Refereed)
  • 38. Clack, Jennifer
    et al.
    Ahlberg, Per
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    Blom, Henning
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    Ontogeny of the humerus in Ichthyostega.2005In: PaleoBios, ISSN 0031-0298, Vol. 25, no 2 (supplement), p. 30-Article in journal (Other scientific)
  • 39. Clack, Jenny A.
    et al.
    Ahlberg, Per E.
    Blom, Henning
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology.
    Ontogeny of the humerus in Ichthyostega2006In: SVPCA, Paris. Abstracts, 2006Conference paper (Other (popular scientific, debate etc.))
  • 40. Clement, Gael
    et al.
    Blom, Henning
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    Daeschler, Edward, B.
    Famennian vertebrate biogeography emphasizing euramerica: south margin (pennsylvania, belgium) vs inland (east greenland).2006In: Geological Society of America Abstracts with Programs, 2006, p. 341-Conference paper (Other (popular scientific, debate etc.))
  • 41. Cunningham, John A.
    et al.
    Ruecklin, Martin
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Botella, Hector
    Donoghue, Philip C. J.
    Testing models of dental development in the earliest bony vertebrates, Andreolepis and Lophosteus2012In: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 8, no 5, p. 833-837Article in journal (Refereed)
    Abstract [en]

    Theories on the development and evolution of teeth have long been biased by the fallacy that chondrichthyans reflect the ancestral condition for jawed vertebrates. However, correctly resolving the nature of the primitive vertebrate dentition is challenged by a dearth of evidence on dental development in primitive osteichthyans. Jaw elements from the Silurian-Devonian stem-osteichthyans Lophosteus and Andreolepis have been described to bear a dentition arranged in longitudinal rows and vertical files, reminiscent of a pattern of successional development. We tested this inference, using synchrotron radiation X-ray tomographic microscopy (SRXTM) to reveal the pattern of skeletal development preserved in the sclerochronology of the mineralized tissues. The tooth-like tubercles represent focal elaborations of dentine within otherwise continuous sheets of the dermal skeleton, present in at least three stacked generations. Thus, the tubercles are not discrete modular teeth and their arrangement into rows and files is a feature of the dermal ornamentation that does not reflect a polarity of development or linear succession. These fossil remains have no bearing on the nature of the dentition in osteichthyans and, indeed, our results raise questions concerning the homologies of these bones and the phylogenetic classification of Andreolepis and Lophosteus.

  • 42.
    Fadel, Alexandre
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology.
    Zigaite, Zivile
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Perez-Huerta, Alberto
    Jeffries, Teresa
    Maersse, Tiiu
    Ahlberg, Per Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Palaeoenvironmental signatures revealed from rare earth element (REE) compositions of vertebrate microremains of the Vesiku Bone Bed (Homerian, Wenlock), Saaremaa Island, Estonia2015In: Estonian journal of earth sciences, ISSN 1736-4728, E-ISSN 1736-7557, Vol. 64, no 1, p. 36-41Article in journal (Refereed)
    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.

  • 43. Friedman, Matt
    et al.
    Blom, Henning
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology. Evolutionär organismbiologi.
    A new actinopterygian from the Famennian of East Greenland and the interrelationship on Devonian ray-finned fishes2006In: Journal of Paleontology, Vol. 80, no 6, p. 1186-1204Article in journal (Refereed)
  • 44.
    Grahn, Jessica
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Ahlberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    The primitive antiarch Yunnanolepis from China: a microtomographic study2011In: 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, p. 8-9Conference paper (Other academic)
    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.

  • 45. Hairapetian, Vachik
    et al.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Turner, Susan
    Early Frasnian thelodont scales from central Iran and their implications for turiniid taxonomy, systematics and distribution2016In: Journal of Vertebrate Paleontology, ISSN 0272-4634, E-ISSN 1937-2809, Vol. 36, no 3, article id e1100632Article in journal (Refereed)
    Abstract [en]

    We describe isolated shark teeth collected in levels of the Calafate Formation (Maastrichtian, Late Cretaceous) on the southeast coast of Argentino Lake, Calafate City, Santa Cruz Province, Argentina. The teeth belong to the hexanchiform Notidanodon dentatus, a new species of the squaliform Protosqualus, and an indeterminate species of the echinorhiniform genus Echinorhinus. The record of Notidanodon constitutes the first in South America. The report of Notidanodon associated with plesiosaur remains is in accordance with previous records from around the world. Protosqualus argentinensis, nov. sp., which is the first record of the genus in South America, is characterized by having teeth with a apicobasally tall root and serrated cutting edges, among other features.Echinorhinus sp. constitutes one of the oldest records of this genus on the continent and one of the few Mesozoic records worldwide. This shark association is clearly distinct from coeval selachian faunas from northern Patagonia, which exhibit clear Tethyan influences. Instead, it shows some similarities to other high-latitude selachian faunas, including Australia, New Zealand, and Antarctica. It is possible that the Cretaceous selachian assemblages of Patagonia may be separated into two different associations: northern Patagonian faunas are related to more temperate associations of lower paleolatitudes, whereas those of southern Patagonia are closer to other southern localities.

  • 46.
    Jerve, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology. Imperial Coll London, Dept Life Sci, Ascot, Berks, England.
    Qu, Qingming
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology. Univ Ottawa, Ctr Adv Res Environm Genom, Ottawa, ON, Canada.
    Sanchez, Sophie
    Uppsala University, Science for Life Laboratory, SciLifeLab. European Synchrotron Radiat Facil, Grenoble, France.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Ahlberg, Per Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Three-dimensional paleohistology of the scale and median fin spine of Lophosteus superbus (Pander 1856)2016In: PeerJ, ISSN 2167-8359, E-ISSN 2167-8359, Vol. 4, article id e2521Article in journal (Refereed)
    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.

  • 47. Kullander, Sven O.
    et al.
    Stach, Thomas
    Hansson, Hans G.
    Delling, Bo
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Nationalnyckeln till Sveriges Flora och Fauna: [DZ 1-34], Ryggsträngsdjur: lansettfiskar – broskfiskar : Chordata : Branchiostomatidae – Chondrichthyes2011Book (Other (popular science, discussion, etc.))
  • 48.
    Lundgren, Mette
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Phylogenetic patterns in the heterostracan families Cyathaspidae, Ariaspidae and Ctenaspidae2011In: 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, p. 16-17Conference paper (Other academic)
    Abstract [en]

    The order Heterostraci includes early armoured vertebrates that are defined by a pair of common external branchial openings on either side of the head. The position of these openings and their arrangement in relation to the plates of the dermal armour has been shown to vary in different species of the Cyathaspidae, Ariaspidae and Ctenaspidae (previously grouped in the family Cyathaspididae). In order to explore evolutionary patterns in the branchial region of heterostracans, a phylogenetic analysis comprising 55 skeletal characters and 37 species-level taxa belonging to the Cyathaspidae, Ariaspidae and Ctenaspidae was carried out; this is the first cladistic appraisal of these heterostracan families. The resulting trees place Asketaspis interstincta in a basal position with all other taxa forming a discrete monophyletic clade. This infers aprogressional shift of the branchial opening and rearrangement of the adjacent dermal plates in Alainaspis, Allocryptaspis, and culminating in Ctenaspidae where the branchial opening is relocated to the posterolatertal corner of the dorsal shield and coincides with the loss of the superficial layer of the dermal armour.

  • 49.
    Lundgren, Mette
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Phylogenetic relationships of the cyathaspidids (Heterostraci)2013In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 135, no 1, p. 74-84Article in journal (Refereed)
    Abstract [en]

    The present analysis investigates for the first time the phylogenetic relationships of the cyathaspidid heterostracans by the principle of global parsimony on the basis of 36 species and 1 outgroup taxon. In this study, which assumes cyathaspidid monophyly, states for 61 characters were compiled and analysed using maximum parsimony methods, resulting in nine shortest trees of 122 steps each. The strict consensus tree shows a high degree of homoplasy and challenges previous classification schemes. The consensus topology supports previous arguments that the tolypelepids with their characteristic scale-like ornament occupy a basal position among the cyathaspidids.

  • 50. Miller, C. G.
    et al.
    Blom, Henning
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Physiology and Developmental Biology. Evolutionär organismbiologi.
    Märss, T.
    Fossils explained 46: Anaspids2003In: Geology Today, Vol. 19, p. 111-114Article in journal (Refereed)
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