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Ebbestad, Jan Ove R.ORCID iD iconorcid.org/0000-0001-8769-3572
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Publications (10 of 148) Show all publications
Gubanov, A. P., Ebbestad, J. O. & Bogolepova, O. K. (2018). A new record of the enigmatic mollusc Jinonicella from the Silurian of the Carnic Alps, Austria. Estonian journal of earth sciences, 67(2), 158-164
Open this publication in new window or tab >>A new record of the enigmatic mollusc Jinonicella from the Silurian of the Carnic Alps, Austria
2018 (English)In: Estonian journal of earth sciences, ISSN 1736-4728, E-ISSN 1736-7557, Vol. 67, no 2, p. 158-164Article in journal (Refereed) Published
Abstract [en]

The small enigmatic mollusc Jinonicella kolebabai Pokorny, 1978 is described from the upper Silurian Cardiola Formation at the Rauchkofel Sud section of the Carnic Alps, Austria. The associated conodonts suggest a late Ludlow (Ludfordian) Polygnathoides siluricus conodont Zone. Previous Silurian records of Jinonicella are known from the Wenlock to Ludlow of the Czech Republic, USA, Gotland of Sweden and the Carnic Alps of Austria. The wide distribution of this taxon across different climatic zones and widely separated areas in the Silurian is problematic, and it is unclear whether Jinonicella was present in high-latitude areas before the end-Ordovician cooling and mass extinction or was dispersed during the Silurian. Possible planktotrophy in Jinonicella and Silurian ocean circulation patterns may explain the dispersal, but within the framework of current palaeogeographical reconstructions the model does not adequately explain an equatorial to polar distribution of other contemporaneous benthic faunas from these areas.

Place, publisher, year, edition, pages
ESTONIAN ACADEMY PUBLISHERS, 2018
Keywords
Silurian, Carnic Alps, problematic mollusc, Jinonicella, palaeogeography
National Category
Geology
Identifiers
urn:nbn:se:uu:diva-361297 (URN)10.3176/earth.2018.12 (DOI)000439004100005 ()
Available from: 2018-09-26 Created: 2018-09-26 Last updated: 2018-09-26Bibliographically approved
Berg-Madsen, V., Valent, M. & Ebbestad, J. O. (2018). An orthothecid hyolith with a digestive tract from the early Cambrian of Bornholm, Denmark. GFF, 140(1), 25-37
Open this publication in new window or tab >>An orthothecid hyolith with a digestive tract from the early Cambrian of Bornholm, Denmark
2018 (English)In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 140, no 1, p. 25-37Article in journal (Refereed) Published
Abstract [en]

The hyolith assemblage from the early Cambrian of Bornholm, Denmark, shows a higher diversity than contemporary assemblages in Baltoscandia. The most common species in the Green Shales (Laesa Formation, Norretorp Member, Cambrian Stage 3), is Hyolithes [=Hyolithus] (Orthotheca) johnstrupi Holm, 1893. A specimen of this species shows a well-preserved and almost complete digestive tract, folded into an approximately 22mm long chevron-like structure comprised of at least 20 arcuate loops on the ventral side and a flattened, gently sinuous to straight anal tube on the dorsal side. The thin, phosphatic outer shell layer of the conch is crushed under the digestive tract due to compaction while the digestive tract is preserved in three dimensions and appears undisturbed. The shape of the digestive tract is similar to that of the middle Cambrian Guduguwan hardmani (Etheridge) from Australia and the lower Cambrian specimens from Russia described by Mekova & Sysoev. The Danish specimen is probably an adult, lending support to the idea that the orthothecid digestive tract becomes more complex during ontogeny. Hyolithus (Orthotheca) johnstrupi is revised and here referred to Circotheca Sysoev, 1958.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2018
Keywords
Orthotheca johnstrupi revised, digestive tract, early Cambrian, Bornholm, Denmark
National Category
Geology
Identifiers
urn:nbn:se:uu:diva-356329 (URN)10.1080/11035897.2018.1432680 (DOI)000432160200003 ()
Available from: 2018-07-25 Created: 2018-07-25 Last updated: 2018-07-25Bibliographically approved
Weidner, T. & Ebbestad, J. O. (2018). Anopolenus henrici Salter, a middle Cambrian Drumian centropleurid trilobite from the Alum Shale Formation of Scandinavia. Bulletin of the Geological Society of Denmark, 66, 223-228
Open this publication in new window or tab >>Anopolenus henrici Salter, a middle Cambrian Drumian centropleurid trilobite from the Alum Shale Formation of Scandinavia
2018 (English)In: Bulletin of the Geological Society of Denmark, ISSN 0011-6297, E-ISSN 2245-7070, Vol. 66, p. 223-228Article in journal (Refereed) Published
Abstract [en]

Centropleurid trilobites include five genera of which Centropleura Angelin, Anopolenus Salter, Clarella Howell and Luhops Snajdr are known from eight species in the traditional middle Cambrian (Miaolingian Series, Drumian Stage) of Sweden and Denmark (Bornholm). Beishanella Xiang & Zhang has not been recorded in Scandinavia so far, and no centropleurids have been reported from Norway. Of these taxa, only Centropleura is common in Scandinavia. Two pygidia previously identified as Centropleura sp. and Anopolenus sp. from erratics in Germany and Bornholm, respectively, as well as a new pygidum from Scania in Sweden are here identified as Anopolenus henrici Salter. Elsewhere, the species is known from Wales, Avalonian Canada, Siberia, Alaska, and Sardinia, occurring in the A. atavus and P. punctuosus zones (the former in Siberia only). The presence of this species increases the known diversity of Centropleuridae in Scandinavia and is important for correlation between Baltica and Avalonia.

Place, publisher, year, edition, pages
GEOLOGICAL SOC DENMARK, 2018
Keywords
Centropleurid trilobite, Miaolingian, Drumian, Alum Shale Formation, Bornholm, Scania, Scandinavia
National Category
Geology
Identifiers
urn:nbn:se:uu:diva-369435 (URN)000449616600001 ()
Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2019-01-22Bibliographically approved
Jensen, S., Hogstrom, A. E. S., Hoyberget, M., Meinhold, G., McIlroy, D., Ebbestad, J. O., . . . Palacios, T. (2018). New occurrences of Palaeopascichnus from the Stahpogieddi Formation, Arctic Norway, and their bearing on the age of the Varanger Ice Age. Paper presented at International Symposium on the Ediacaran-Cambrian Transition (ISECT), JUN, 2017, St. John's, CANADA. Canadian journal of earth sciences (Print), 55(11), 1253-1261
Open this publication in new window or tab >>New occurrences of Palaeopascichnus from the Stahpogieddi Formation, Arctic Norway, and their bearing on the age of the Varanger Ice Age
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2018 (English)In: Canadian journal of earth sciences (Print), ISSN 0008-4077, E-ISSN 1480-3313, Vol. 55, no 11, p. 1253-1261Article in journal (Refereed) Published
Abstract [en]

We report on new occurrences of the late Ediacaran problematicum Palaeopascichnus (Protista?) from the Stahpogieddi Formation, Arctic Norway. The stratigraphically lowest occurrences are in beds transitional between the Lillevannet and Indreelva members: the highest in the second cycle of the Manndrapselva Member, stratigraphically close to the lowest occurrences of Cambrian-type trace fossils. This establishes a long stratigraphical range of Palaeopascichnus on the Digermulen Peninsula, as has been previously documented from Newfoundland, South Australia, and elsewhere in Baltica. The age range of Palaeopascichnus in Avalonia and Baltica is from similar to 565 to 541 Ma. Since the transition from the Mortensnes Formation to the Stahpogieddi Formation is without a major break in sedimentation, this supports the inference that the underlying glacigenic Mortensnes Formation is ca. 580 Ma, and therefore Gaskiers-equivalent, or younger.

Place, publisher, year, edition, pages
CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS, 2018
National Category
Other Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-369594 (URN)10.1139/cjes-2018-0035 (DOI)000449166700005 ()
Conference
International Symposium on the Ediacaran-Cambrian Transition (ISECT), JUN, 2017, St. John's, CANADA
Available from: 2018-12-19 Created: 2018-12-19 Last updated: 2018-12-19Bibliographically approved
Jensen, S., Hogstrom, A. E. S., Almond, J., Taylor, W. L., Meinhold, G., Hoyberget, M., . . . Palacios, T. (2018). Scratch circles from the Ediacaran and Cambrian of Arctic Norway and southern Africa, with a review of scratch circle occurrences. Bulletin of Geosciences, 93(3), 287-304
Open this publication in new window or tab >>Scratch circles from the Ediacaran and Cambrian of Arctic Norway and southern Africa, with a review of scratch circle occurrences
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2018 (English)In: Bulletin of Geosciences, ISSN 1214-1119, E-ISSN 1802-8225, Vol. 93, no 3, p. 287-304Article, review/survey (Refereed) Published
Abstract [en]

Scratch circles - bedding plane parallel sedimentary structures formed by the passive rotation of a tethered organism into the surrounding sediment - are relatively rare in the geological record. Here new occurrences of scratch circles are described from the Ediacaran-Cambrian Stahpogieddi Formation, Digermulen Peninsula, Arctic Norway, and from the Ediacaran Nudaus and Urusis formations, Nama Group, of southern Africa. A literature survey confirms a previously noted concentration of scratch circles reported from shallow marine upper Ediacaran-lower Cambrian and paralic Carboniferous rocks. Scratch circle identification and nomenclature are discussed. The stratigraphical range of the trace fossils Treptichnus pedum and Gyrolithes isp. in the Stahpogieddi Formation are extended downward. Combined with earlier reports of Harlaniella podolica this adds new precision to the placement of the Ediacaran-Cambrian boundary on the Digermulen Peninsula.

Place, publisher, year, edition, pages
CZECH GEOLOGICAL SURVEY, 2018
Keywords
scratch circles, Ediacaran, Cambrian, Norway, Republic of South Africa, Namibia, trace fossils
National Category
Other Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-363891 (URN)10.3140/bull.geosci.1685 (DOI)000441904600002 ()
Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2018-11-12Bibliographically approved
Egenhoff, S., Maletz, J., Ahlberg, P., Mast, A., Frisk, Å., Ebbestad, J. O. & Newby, W. (2018). Sedimentology of the Lower Ordovician (upper Tremadocian) Bjørkasholmen Formation at Flagabro, southern Sweden. GFF, 140(1), 55-65
Open this publication in new window or tab >>Sedimentology of the Lower Ordovician (upper Tremadocian) Bjørkasholmen Formation at Flagabro, southern Sweden
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2018 (English)In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 140, no 1, p. 55-65Article in journal (Refereed) Published
Abstract [en]

The Lower Ordovician Bjørkasholmen Formation at Flagabro, Scania, southern Sweden, consists of a 0.8m thick succession of carbonates with three siliciclastic mudstones, 5, 1 and 100mm thick, intercalated in the central part of the unit. Carbonate and siliciclastic mudstone beds show both normal and inverse grading. The carbonates are mud-rich and subdivided into a mudstone, a wackestone and a packstone facies. Grain types in the carbonates are mostly shells and shell fragments of brachiopods and trilobites. The carbonate rocks are strongly bioturbated seen as in roundish burrows filled with mud and a clear cement; additionally, bioturbation is reflected in the random orientation of shells. The siliciclastic mudstones are subdivided into two facies; one contains large amounts of shells and is in part grain-supported, the other is matrix-dominated and laminated to massive. The succession reflects sedimentation on a low-inclined shelf equivalent to a mid-ramp to basinal setting. Most mud- and wackestones (facies 3 and 4) represent fair-weather sedimentation, and the intercalated wacke- and packstones (facies 4 and 5) represent concentration of shell debris during high-energy storm. The siliciclastic mudstones in the central part of the succession reflect deposition in a basinal setting. The entire BjOrkasholmen Formation at Flagabro is equivalent to a lowstand of third (?) order without a well-developed internal cyclicity and is in that respect similar to the Bjørkasholmen Formation of oland, but different from the age-equivalent Norwegian sections.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2018
Keywords
Bjørkasholmen Formation, carbonates, siliciclastic mudstones, Flagabro
National Category
Geology
Identifiers
urn:nbn:se:uu:diva-356330 (URN)10.1080/11035897.2018.1445777 (DOI)000432160200006 ()
Available from: 2018-07-24 Created: 2018-07-24 Last updated: 2018-07-24Bibliographically approved
Wang, Q., Sun, L. & Ebbestad, J. O. (2018). The Dates of the Discovery of the First Peking Man Fossil Teeth. Asian Perspectives, 57(2), 267-280
Open this publication in new window or tab >>The Dates of the Discovery of the First Peking Man Fossil Teeth
2018 (English)In: Asian Perspectives, Vol. 57, no 2, p. 267-280Article in journal (Refereed) Published
Abstract [en]

Four teeth of Peking Man from Zhoukoudian, excavated by Otto Zdansky in 1921 and 1923 and currently housed in the Museum of Evolution at Uppsala University, are among the most treasured finds in palaeoanthropology, not only because of their scientific value but also for their important historical and cultural significance. It is generally acknowledged that the first fossil evidence of Peking Man was two teeth unearthed by Zdansky during his excavations at Zhoukoudian in 1921 and 1923. However, the exact dates and details of their collection and identification have been documented inconsistently in the literature. We reexamine this matter and find that, due to incompleteness and ambiguity of early documentation of the discovery of the first Peking Man teeth, the facts surrounding their collection and identification remain uncertain. Had Zdansky documented and revealed his findings on the earliest occasion, the early history of Zhoukoudian and discoveries of first Peking Man fossils would have been more precisely known and the development of the field of palaeoanthropology in early twentieth century China would have been different.

Keywords
Peking Man, Museum of Evolution, Otto Zdansky
National Category
Other Earth and Related Environmental Sciences
Research subject
Earth Science with specialization in Historical Geology and Palaeontology
Identifiers
urn:nbn:se:uu:diva-371698 (URN)10.1353/asi.2018.0017 (DOI)000456317000005 ()
Available from: 2018-12-27 Created: 2018-12-27 Last updated: 2019-02-19Bibliographically approved
Streng, M., Ebbestad, J. O. & Berg-Madsen, V. (2017). Cambrian palaeoscolecids (Cycloneuralia) of southern Scandinavia. Papers in Palaeontology, 3(1), 21-48
Open this publication in new window or tab >>Cambrian palaeoscolecids (Cycloneuralia) of southern Scandinavia
2017 (English)In: Papers in Palaeontology, ISSN 2056-2802, Vol. 3, no 1, p. 21-48Article in journal (Refereed) Published
Abstract [en]

A previously undocumented diversity of Cambrian palaeoscolecids is described from localities in Sweden, Norway and Denmark. The material described here includes isolated sclerites as well as the first macroscopic specimens reported from the palaeocontinent Baltica. The sclerites are all of early middle Cambrian age (Ptychagnostus gibbus Biozone) and are assigned to at least four new species of Hadimopanella, two of which are formally introduced: H. incubo sp. nov. and H. oelandiana sp. nov. The two macroscopic specimens are of late early Cambrian (Ellipsocephalus lunatus Biozone) and early middle Cambrian age (Acadoparadoxides oelandicus Biozone), respectively. The early Cambrian specimen is described as Maotianshania? sp. and comprises an incomplete annulated trunk fragment which is uniformly covered with circular sclerites, indicative of the palaeoscolecid family Maotianshaniidae. This is the first record of this family outside China. The middle Cambrian specimen is almost complete and introduced as Wronascolex? johanssoni sp. nov. It is characterized by a previously undocumented distribution of its Hadimopanella-like sclerites which increase in size and change ornamentation from the anterior to the posterior end of the distinctly annulated trunk. The observed distribution pattern can explain the high variability of species of the sclerite-based genus Hadimopanella as well as the occurrence of rare morphotypes of Hadimopanella in otherwise rich samples. Available data on the ontogeny of palaeoscolecids regarding the relationship between body and sclerite size of a taxon are evaluated. It is concluded that sclerite size might be species specific and should be considered when comparing taxa with morphological similar sclerites.

National Category
Other Earth and Related Environmental Sciences
Research subject
Earth Science with specialization in Historical Geology and Palaeontology
Identifiers
urn:nbn:se:uu:diva-311368 (URN)10.1002/spp2.1067 (DOI)000397149200002 ()
Available from: 2016-12-26 Created: 2016-12-26 Last updated: 2018-09-07Bibliographically approved
Ebbestad, J. O. & Weidner, T. (2017). Extreme Protomeric Development In A Burlingiid Trilobite From Cambrian Glacial Erratics Of Denmark. Palaeontology, 60(2), 233-253
Open this publication in new window or tab >>Extreme Protomeric Development In A Burlingiid Trilobite From Cambrian Glacial Erratics Of Denmark
2017 (English)In: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 60, no 2, p. 233-253Article in journal (Refereed) Published
Abstract [en]

Pengia Geyer & Corbacho is a Cambrian burlingiid trilobite with fused trunk segments devoid of any articulation in the anamorphic and epimorphic phases of development. The type species is Pengia fusilis (Peng etal.) from the Wanshania wanshanensis Zone of China. Here we describe a second species, Pengia palsgaardia sp. nov., from the Lejopyge laevigata Zone of the Paradoxides forchhammeri Superzone. It comes from a glacial erratic in Denmark which probably originated in the Alum Shale Formation of Vastergotland, Sweden. Pengia palsgaardia is a large burlingiid (similar to 10mm in length), with 14 fused segments in the trunk whose boundaries are marked by ridges. The axis is narrow, with the axial furrows faintly indicated or effaced across the median. Laterally along the axis and the tapering glabella, symmetrical globular lobes are developed that are pinched at their base. During ontogeny the glabellar furrows are pit-like adaxially but shallow towards the axial furrow as the globular lobes develop. Their pit-like appearance in Pengia palsgaardia and some other burlingiid species is not considered similar to the condition seen in oryctocephalid trilobites. A median preglabellar ridge resembling that of Schmalenseeia Moberg develops late in ontogeny but in early ontogeny the preglabellar field resembles that of Burlingia Walcott, Alumenella Geyer & Corbacho and Niordilobites Geyer & Corbacho. This gives Pengia a more basal position in the schmalenseeid lineage, outside the derived Schmalenseeia. In mature specimens the facial sutures in P.palsgaardia are fused, but an ocular suture may have been present. During ontogeny Pengia would have gone through the anamorphic and protomeric protaspid segmental conditions, but articulation between either the cephalon and pygidium, or pygidium and thoracic segments of the trunk never developed so it did not progress beyond the protaspid phase. This extreme protomeric development is considered to be a derived feature in Pengia.

Place, publisher, year, edition, pages
WILEY, 2017
Keywords
Pengia, Burlingia, Schmalenseeia, morphology, Cambrian, protomeric development
National Category
Geosciences, Multidisciplinary
Identifiers
urn:nbn:se:uu:diva-320396 (URN)10.1111/pala.12279 (DOI)000394993300008 ()
Available from: 2017-04-20 Created: 2017-04-20 Last updated: 2017-04-20Bibliographically approved
Ebbestad, J. O. & Carlos Gutierrez-Marco, J. (2017). First occurrence of Pterotheca (Gastropoda) from the Silurian (Aeronian) of Spain. Geobios, 50(2), 97-104
Open this publication in new window or tab >>First occurrence of Pterotheca (Gastropoda) from the Silurian (Aeronian) of Spain
2017 (English)In: Geobios, ISSN 0016-6995, E-ISSN 1777-5728, Vol. 50, no 2, p. 97-104Article in journal (Refereed) Published
Abstract [en]

Pterotheca hispanica nov. sp. is described from the basal beds (Stimulograptus sedgwickii graptolite Zone) of the Formigoso Fm., in the Cantabrian Zone of the Iberian Massif, north-western Spain. This specialized bellerophontoid gastropod is for the first time recorded in the Silurian of peri-Gondwana; it is the only Aeronian species known so far. Its most closely allied relatives are from higher beds placed in the Telychian of Scotland. Pterotheca is considered a highly derived genus within the Pterothecinae of the Carinaropsidae, with the strongly reduced to absent coiling and the growth of the septum being synapomorphies. In the present work it is shown that not only the apical angle of the septum can be used to distinguish species, but also the relative length and width of the septum. In some cases, the slit may extend as far back as the anterior part of the internal septum. Silurian species were hitherto only found in marginal Laurentian and Eastern Avalonian settings. Pterotheca is absent from central Laurentia and Baltica, where it could be expected to be present based on its wide Ordovician distribution. In the light of this, the occurrence of the genus in the Aeronian of Spain seems difficult to explain, albeit the genus was present in peri-Gondwana prior to the end-Ordovician extinction. The extreme scarcity of described taxa recorded from Avalonia, Baltica and Iberia during the Early Silurian may explain this patchy distribution.

Keywords
Bellerophontoidea, Carinaropsidae, Pterothecinae, Silurian, Palaeobiogeography, Iberian Peninsula
National Category
Biological Systematics
Identifiers
urn:nbn:se:uu:diva-329142 (URN)10.1016/j.geobios.2017.02.003 (DOI)000403386300002 ()
Available from: 2017-10-09 Created: 2017-10-09 Last updated: 2017-10-09Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-8769-3572

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