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Erptonyx, oldest parareptilian from Carboniferous of Canada (free pdf)

Ben Creisler

A new online paper with free pdf:

Sean P. Modesto, Diane M. Scott, Mark J. MacDougall, Hans-Dieter Sues,
David C. Evans, Robert R. Reisz (2015)
The oldest parareptile and the early diversification of reptiles.
Proceedings of the Royal Society B (advance online publication)
DOI: 10.1098/rspb.2014.1912

Amniotes, tetrapods that evolved the cleidoic egg and thus
independence from aquatic larval stages, appeared ca 314 Ma during the
Coal Age. The rapid diversification of amniotes and other tetrapods
over the course of the Late Carboniferous period was recently
attributed to the fragmentation of coal-swamp rainforests ca 307 Ma.
However, the amniote fossil record during the Carboniferous is
relatively sparse, with ca 33% of the diversity represented by single
specimens for each species. We describe here a new species of
reptilian amniote that was collected from uppermost Carboniferous
rocks of Prince Edward Island, Canada. Erpetonyx arsenaultorum gen. et
sp. nov. is a new parareptile distinguished by 29 presacral vertebrae
and autapomorphies of the carpus. Phylogenetic analyses of
parareptiles reveal E. arsenaultorum as the closest relative of
bolosaurids. Stratigraphic calibration of our results indicates that
parareptiles began their evolutionary radiation before the close of
the Carboniferous Period, and that the diversity of end-Carboniferous
reptiles is 80% greater than suggested by previous work. Latest
Carboniferous reptiles were still half as diverse as synapsid
amniotes, a disparity that may be attributable to preservational
biases, to collecting biases, to the origin of herbivory in tetrapods
or any combination of these factors.

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