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Isaure Scavezzoni & Valentin Fischer (2021).
The postcranial skeleton of Cerrejonisuchus improcerus (Crocodyliformes: Dyrosauridae) and the unusual anatomy of dyrosaurids.
PeerJ 9:e11222
doi:
https://doi.org/10.7717/peerj.11222https://peerj.com/articles/11222/Dyrosauridae is a clade of neosuchian crocodyliforms that diversified in terrestrial and aquatic environments across the Cretaceous-Paleogene transition. The postcranial anatomy of dyrosaurids has long been overlooked, obscuring both their disparity and their locomotive adaptations. Here we thoroughly describe of the postcranial remains of an unusually small dyrosaurid, Cerrejonisuchus improcerus, from the middle-late Paleocene CerrejÃn Formation of Colombia, and we provide a wealth of new data concerning the postcranial anatomy of the key dyrosaurids: Congosaurus bequaerti and Hyposaurus rogersii. We identify a series of postcranial autapomorphies in Cerrejonisuchus improcerus (an elliptic-shaped odontoid laterally wide, a ulna possessing a double concavity, a fibula bearing a widely flattened proximal end, a pubis showing a large non-triangular distal surface) as well as functionally-important traits such as a relatively long ulna (85% of the humerusâ length), short forelimb (83% of hindlimbâs length), or thoracic vertebra bearing comparatively large lateral process (with widened parapophysis and diapophysis) along with strongly arched thoracic ribs allowing a more sturdy and cylindrical rib cage. These indicate a more terrestrial lifestyle for Cerrejonisuchus compared to the derived members of the clade. We also built a dataset of 187 traits on 27 taxa, that extensively samples the cranial and postcranial architectures of exemplar crocodyliforms. We analyze these data in via Principal Coordinate Analysis (PCoA) to visualize the postcranial morphospace occupation of Dyrosauridae, Thalattosuchia, and Crocodylia. Our data reveal the existence of a distinctive postcranial anatomy for Dyrosauridae that is markedly distinct from that of crocodylians. As a result, modern crocodylians are probably not good functional analog for extinct crocodyliformes. Postcranial data should also be more widely used in phylogenetic and disparity analyses of Crocodyliformes.
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Nathalie BARDET, Delphine Desmares, Raquel SANCHEZ-PELLICER & Silvia GARDIN (2021)
Rediscovery of "Liodon" asiaticum RÃpelin, 1915, a Mosasaurini (Squamata, Mosasauridae, Mosasaurinae) from the Upper Cretaceous of the vicinity of Jerusalem â Biostratigraphical insights from microfossils.
in FOLIE A., BUFFETAUT E., BARDET N., HOUSSAYE A., GHEERBRANT E. & LAURIN M. (eds), Palaeobiology and palaeobiogeography of amphibians and reptiles: An homage to Jean-Claude Rage.
Comptes Rendus Palevol 20 (20): 351-372
doi:
https://doi.org/10.5852/cr-palevol2021v20a20https://sciencepress.mnhn.fr/en/periodiques/comptes-rendus-palevol/20/20
Briefly mentioned in 1915 by the palaeontologist RÃpelin, the mosasaurid Liodon asiaticum RÃpelin, 1915 was found by a missionary to Africa, a Father Ruffier, in Late Cretaceous strata near Jerusalem (without further details on the exact provenance). This material was never described in detail, figured, or revised and was recently rediscovered in the collections of the MusÃum dâhistoire naturelle of Marseille (Provence, southern France). Here we describe and figure for the first time this material, which now includes more specimens than the original lot mentioned by RÃpelin, and we propose new systematic assignments for the identified specimens. First of all we demonstrate that the five original vertebrae briefly described by RÃpelin representing a composite assemblage and being are not diagnostic at the specific level. Thus Liodon asiaticum should be considered a nomem dubium. The most complete and diagnostic specimen belongs to a Mosasaurini (Mosasaurinae) incertae sedis, close to Mosasaurus Conybeare, 1822 and Plotosaurus Camp, 1951, as shown by in the unique configuration of its frontal-parietal-postorbitofrontal complex. The two other specimens are referred to identified as indeterminate Mosasaurinae. The study of several groups of microfossils (calcareous nannofossils, planktonic foraminifera and palynomorphs) found in the white chalk preserved with most of the bones constrains the age of these mosasaurid remains to the lower part of the middle Campanian (C. plummerae (Gandolfi, 1955) / G. rosetta (Carsey, 1926) and CC18 / UC14-15a Zones). This corresponds to the local Mishash Formation that crops out extensively East of Jerusalem (Mount of Olives and surroundings). Father Ruffier probably collected these bones in one of the outcrops of this formation, possibly not very far from where he worked and lived (Saint-Anne Community in Jerusalem). These chalky levels, common in the Middle East, represent a shallow and rather open marine environment, possibly near-shore.
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The naming of the Permian by Roderick Murchison in 1841 is well known. This is partly because he âcompletedâ the stratigraphic column at system level, but also because of the exotic aspects of his extended fieldwork in remote parts of Russia and Murchison's reputed character. Here, we explore several debated and controversial aspects of this act, benefiting from access to documents and reports notably from Russian sources. Murchison or Sedgwick could have provided a name for the unnamed lower New Red Sandstone in 1835 based on British successions or those in Germany, so perhaps the Imperial aim of naming time from British geology was not the urgent task some have assumed. Murchison has been painted as arrogant and Imperialistic, which was doubtless true, but at the time many saw him as a great leader, even an attractive individual. Others suggest he succeeded because he stood on the shoulders of local geologists; however, his abilities at brilliant and rapid geological synthesis are undoubted. Two unexpected consequences of his work are that this arch conservative is revered in Russia as a hero of geological endeavours, and, for all his bombast, his âPermianâ was not widely accepted until 100 years after its naming.