Uchman A.,Jagiellonian University |
Gazdzicki A.,Instytut Paleobiologii
Polish Polar Research | Year: 2010
Trace fossils Phymatoderma melvillensis isp. nov., Thalassinoides isp., ?Nereites isp. and Planolites isp. are reported from the glacimarine sediments of the Cape Melville Formation (Lower Miocene) of King George Island, West Antarctica. Their occurrence and strong bioturbation of sediments point to an offshore or deeper (outer shelf or upper slope) environment. Deep marine crab Antarctidromia inflata Förster, 1985, has been found in Thalassinoides isp. The tracemaker (?crustacean) of Phymatoderma melvillensis rereworked pelletal sediments probably during times of food deficiency.
Machalski M.,Instytut Paleobiologii |
Jagt J.W.M.,Natuurhistorisch Museum Maastricht |
Alekseev A.S.,Russian Academy of Sciences |
Jagt-Yazykova E.A.,University of Opole
Acta Palaeontologica Polonica | Year: 2012
A complete uppermost Maastrichtian-Danian succession in the Sumbar River section, western Kopet Dagh (southwest Turkmenistan, Central Asia), constitutes one of the few instances in the world where the fossil record of the last ammonites can be directly positioned with respect to the iridium-rich, impact-related clay layer, which defines the Cretaceous-Paleogene (K-Pg) boundary. Two ammonite taxa, Baculites cf. vertebralis and Hoploscaphites constrictus johnjagti, range up to a level directly beneath the K-Pg boundary clay in the Sumbar River section. Thus, these two forms probably survived until the very end of the Maastrichtian in the western Kopet Dagh area. The terminal Maastrichtian ammonite records from the Sumbar River area represent the southeasternmost occurrences of these essentially Boreal taxa. Copyright © 2012.
Sulej T.,Instytut Paleobiologii
Zoological Journal of the Linnean Society | Year: 2010
Disarticulated bones of several individuals recovered from the Late Triassic fluvial and lacustrine deposits at Krasiejów, Poland, are here described, allowing the restoration of the skull structure of a new aetosaurian archosaur: Stagonolepis olenkae sp. nov. The Krasiejów deposits probably correspond in age to the Lehrberg Beds (late Carnian) of Baden-Württemberg, Germany. The stratigraphical position of the new taxon combined with other available evidence is used to propose a model of aetosaurian evolution. The proposed phylogenetic position of Aetosaurus ferratus (Norian, Germany) as the basal aetosaurid is refuted and this species is instead proposed to be the most derived member of the Stagonolepis-Aetosaurus evolutionary lineage. Gradual change in several morphological characters can be observed from Stagonolepis robertsoni, through the new species from Krasiejów, to the stratigraphically youngest Aetosaurus ferratus. These changes include a decrease in the number of teeth and a decrease in the convexity of the ventral profile of the maxilla. The anterior elongation of the maxilla is associated with the expansion of the anterior tip of the maxilla towards the naris. In S. robertsoni and S. olenkae, the maxilla extends to middle of the naris, whereas in Aetosaurus, it reaches the anterior half of the naris. © 2010 The Linnean Society of London.
Desojo J.B.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia |
Heckert A.B.,Appalachian State University |
Martz J.W.,Denver Museum of Nature and Science |
Parker W.G.,Petrified Forest National Park |
And 4 more authors.
Geological Society Special Publication | Year: 2013
Aetosauria is a clade of obligately quadrupedal, heavily armoured pseudosuchians known from Upper Triassic (late Carnian-Rhaetian) strata on every modern continent except Australia and Antarctica. As many as 22 genera and 26 species ranging from 1 to 6 m in ength, and with a body mass ranging from less than 10 to more than 500 kg, are known. Aetosauroides scagliai was recently recovered as the most basal aetosaur, placed outside of Stagonolepididae(the last common ancestor of Desmatosuchus and Aetosaurus). Interrelationships among the basal aetosaurs are not well understood but two clades with relatively apomorphic armour-the spinose Desmatosuchinae and the generally wide-bodied Typothoracisinae-are consistently ecognized. Paramedian and lateral osteoderms are often distinctive at the generic level but variation within the carapace is not well understood in many taxa, warranting caution in assigning isolated osteoderms to specific taxa. The aetosaur skull and dentition varies across taxa, and there is increasing evidence that at least some aetosaurs relied on invertebrates and/or small vertebrates s a food source. Histological evidence indicates that, after an initial period of rapid growth, lines of arrested growth (LAGs) are common and later growth was relatively slow. The common and widespread Late Triassic ichnogenus Brachychirotherium probably represents the track of an aetosaur. © The Geological Society of London 2013.
Lamolda M.A.,University of Granada |
Paul C.R.C.,University of Bristol |
Peryt D.,Instytut Paleobiologii |
Pons J.M.,University of Barcelona
Episodes | Year: 2014
The GSSP for the base of the Santonian Stage is defined at 94.4 m in the eastern border of the "Cantera de Margas" quarry, Olazagutia (Navarra, N. Spain: 42° 52′ 05.3" N, 2° 11′ 40" W) and marked by the first occurrence (FO) of the inoceramid bivalve Platyceramus undulatoplicatus. This first occurrence is located about 9 m below the contact between a lower marly unit and an upper more calcareous unit. The FO of the planktonic foraminifer Sigalia carpatica is the secondary marker of the GSSP and first occurs 7 m below the primary marker, but it becomes consistently present about 4.2 m above the boundary. In addition, six peaks in the carbon stable isotope curve can be recognized between the Kingsdown Event 17.2 m below and the Bedwell Event 12.35 m above the GSSP. The basal Santonian GSSP was approved by the International Subcommission on Cretaceous Stratigraphy in September 2010, by the International Commision of Stratigraphy in April 2012, and ratified by the International Union of Geological Sciences in January 2013.