Ben Creisler
Some new non-dino papers with free pdfs:
Free pdf:
Grace L. Varnham, Philip D. Mannion & Christian F. Kammerer (2021)
Spatiotemporal variation in completeness of the early cynodont fossil record and its implications for mammalian evolutionary history
Palaeonology (advance online publication)
doi:
https://doi.org/10.1111/pala.12524https://onlinelibrary.wiley.com/doi/full/10.1111/pala.12524Free pdf:
https://onlinelibrary.wiley.com/doi/pdf/10.1111/pala.12524Data archiving statement:
Data for this study are available in the Dryad Digital Repository:
https://doi.org/10.5061/dryad.w6m905qn9Mammals are the only surviving group of Cynodontia, a synapsid clade that first appeared in the fossil record in the late Permian, ~260 million years ago. Using three metrics that capture skeletal completeness, we quantify the quality of the early cynodont fossil record in time and space to evaluate the impact of sampling and preservational biases on our understanding of the group's evolutionary history. There is no consistent global sampling signal for early cynodonts. Completeness of the cynodont fossil record increases across the Permian-Triassic boundary, peaking in the Early to early Late Triassic. This peak is dominated by specimens from southern Africa and South America, where a highly seasonal climate probably favoured preservation. Completeness is generally lower thereafter, correlating with a shift from a Gondwanan to a predominantly Laurasian fossil record. Phylogenetic and stratigraphic congruence in early cynodonts is high, although their fossil record exhibits less skeletal completeness overall than other tetrapod clades, including the contemporaneous anomodont synapsids. This discrepancy could be due to differences in the diagnosability of their fossils, especially for smallâbodied species. Establishing the timing and assembly of derived (âmammalianâ) anatomical features in Cynodontia is obscured by sampling. Two of the major nodes at which acquisition of mammalian features is concentrated (Cynodontia and Mammaliamorpha) suffer from lengthy intervals of poor sampling before becoming abundant parts of tetrapod faunas. Low completeness in these intervals limits our ability to determine when certain 'key' mammalian characteristics evolved, or to identify the selective pressures that might have driven their origins.
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Free pdf:
JosÃ-Carmelo CORRAL, Ana BERRETEAGA, Francisco Josà POYATO-ARIZA, Nathalie BARDET, Henri CAPPETTA, Marc FLOQUET, Humberto ASTIBIA, Ainara BADIOLA & Xabier PEREDA-SUBERBIOLA (2021)
Stratigraphy, age, and vertebrate palaeontology of the latest Cretaceous Quintanilla la Ojada locality (Basque-Cantabrian Region, northern Spain): a synthesis.
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(7): 91-117
DOI:
https://doi.org/10.5852/cr-palevol2021v20a7https://sciencepress.mnhn.fr/en/periodiques/comptes-rendus-palevol/20/7Free pdf:
https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/comptes-rendus-palevol2021v20a7.pdfThe Quintanilla la Ojada section (Basque-Cantabrian Region, northern Spain) has yielded two assemblages of Late Cretaceous vertebrates, deposited during the Maastrichtian in coastal environments and related to a transgressive lag at the base of the Valdenoceda Formation. Numerous teeth of Elasmobranchii and Actinopterygii are the most prevailing fossil material, although scarce teeth of marine reptiles (Mosasauridae) and dinosaurs (Hadrosauridae) also occur. The presence of one hadrosaurian tooth, a terrestrial taxon, constitutes the first report of ornithischians in the Valdenoceda Formation. The fossil vertebrate association of Quintanilla la Ojada is similar to that discovered in Albaina (TreviÃo County, Burgos), also located in the Basque-Cantabrian Region, although relatively younger in age. Both fossil sites are characterised by a mixture of taxa from the northern and southern margins of the Mediterranean Tethys (north-European and north-African outcrops).
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Free pdf:
Purgatorius mckeeveri sp. nov.
Plesiadapiform mammals, as stem primates, are key to understanding the evolutionary and ecological origins of Pan-Primates and Euarchonta. The Purgatoriidae, as the geologically oldest and most primitive known plesiadapiforms and one of the oldest known placental groups, are also central to the evolutionary radiation of placentals and the Cretaceous-Palaeogene biotic recovery on land. Here, we report new dental fossils of Purgatorius from early Palaeocene (early Puercan) age deposits in northeastern Montana that represent the earliest dated occurrences of plesiadapiforms. We constrain the age of these earliest purgatoriids to magnetochron C29R and most likely to within 105â139 thousand years post-K/Pg boundary. Given the occurrence of at least two species, Purgatorius janisae and a new species, at the locality, we provide the strongest support to date that purgatoriids and, by extension, Pan-Primates, Euarchonta and Placentalia probably originated by the Late Cretaceous. Within 1 million years of their arrival in northeastern Montana, plesiadapiforms outstripped archaic ungulates in numerical abundance and dominated the arboreal omnivore-frugivore niche in mammalian local faunas.
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