The monophyly of Euparkeriidae (Reptilia: Archosauriformes) and the origins of Archosauria: a revision of Dorosuchus neoetus from the Mid-Triassic of Russia

Euparkeria capensis is resolved as the sister taxon to crown 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. In order to test this monophyly, the archosauriform and putative euparkeriid Dorosuchus neoetus from the Mid-Triassic of Russia is reexamined in 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. capens...

在诸多分支系统发育分析中，卡普赛派克鳄（Euparkeria capensis）被复原为冠群主龙类（crown Archosauria）的姊妹群，同时为我们提供了一个可近似主龙类祖先形态的关键外类群。已有多个类群被归入派克鳄科（Euparkeriidae），但该科的单系性仍存疑且基本未得到检验。为验证这一单系性，本文基于近期针对干群主龙类演化的研究成果，重新检视了一件来自俄罗斯中三叠世的主龙形类、疑似派克鳄科成员的新达罗鳄（Dorosuchus neoetus）。研究发现，新达罗鳄具备多项接近主龙类的形态特征，包括一条带有明确尾股肌（m. caudifemoralis musculature）附着区域的S形股骨，但未发现明确无误的主龙类衍征。本次研究首次将新达罗鳄纳入数值化分支系统分析，结果显示其为主龙类+植龙目（Archosauria+Phytosauria）的唯一姊妹群。包含新达罗鳄与卡普赛派克鳄的单系派克鳄科……