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Dorosuchus (Triassic archosauriform from Russia) revised



From: Ben Creisler
bcreisler@gmail.com


A new online paper:

Roland B. Sookias, Andrey G. Sennikov, David J. Gower and Richard J.
Butler (2014)
The monophyly of Euparkeriidae (Reptilia: Archosauriformes) and the
origins of Archosauria: a revision of Dorosuchus neoetus from the
Mid-Triassic of Russia.
Palaeontology (advanced online publication)
DOI: 10.1111/pala.12110
http://onlinelibrary.wiley.com/doi/10.1111/pala.12110/abstract

Euparkeria capensis is resolved as the sister taxon to Archosauria in
many cladistic phylogenies and provides a key outgroup which may
approximate the ancestral archosaur morphology. Several other taxa
have been referred to the family Euparkeriidae, but the monophyly of
this taxon remains doubtful and largely untested. To test this
monophyly, the archosauriform and putative euparkeriid Dorosuchus
neoetus from the Mid-Triassic of Russia is re-examined in the light of
recent work on the evolution of stem archosaurs. Dorosuchus neoetus is
found to possess a number of morphological features that place it
close to Archosauria, including a sigmoidal femur with a clear
attachment region for the m. caudifemoralis musculature, but no
unambiguous archosaurian apomorphies. Dorosuchus neoetus is included
for the first time in a numerical cladistic analysis and is recovered
as the sole sister taxon to Archosauria + Phytosauria. A monophyletic
Euparkeriidae including D. neoetus and E. capensis is slightly less
parsimonious. In addition, a mandible and pterygoid that were
previously referred to D. neoetus subsequent to the original
description of the species are also included separately within the
phylogenetic analysis and are recovered within Archosauria, possibly
raising questions as to their correct taxonomic referral. However,
this phylogenetic placement is based primarily on the absence of
palatal teeth, but the presence or absence of palatal teeth exhibits
considerable homoplasy within Archosauriformes. Based on other aspects
of their morphology, we do not reject the referral of these elements
to D. neoetus.