New clade of enigmatic early archosaurs yields insights into early pseudosuchian phylogeny and the biogeography of the archosaur radiation.
New clade of enigmatic early archosaurs yields insights into early pseudosuchian phylogeny and the biogeography of the archosaur radiation.
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DOI：
10.1186/1471-2148-14-128
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发表时间：
2014-06-10
影响因子：
3.4
通讯作者：
Sookias RB
中科院分区：
文献类型：
--
作者：
Butler RJ;Sullivan C;Ezcurra MD;Liu J;Lecuona A;Sookias RB
三叠纪始龙及其近缘类群(始龙形目)的起源和早期辐射是四足动物进化史上的一个关键事件。这种辐射导致了侏罗纪和白垩纪以恐龙为主的生态系统，以及包括大约10,000种鸟类和鳄鱼物种在内的高度现代原始龙多样性。这一进化辐射的时间和动态目前被几个关键的早期始龙类群的系统发育位置所掩盖，其中包括阿根廷中三叠世的几个种(Gracilisuchus Stipanicorum)和中国(Turfan Osuchus Dabanensis)和永和苏克斯桑比斯(Turfan Osuchus Dabanensis)。这些物种在形态系统发育分析中充当不稳定的“通配符”，降低了系统发育的分辨率。我们提供了新的模式标本的解剖资料，并对早期始祖龙的亲缘关系进行了新的形态系统发育分析。我们的结果表明，这三个以前神秘的类群形成了一个支持良好的中三叠世始龙支系，我们称之为Gracilisuchidae。巨蟹科位于苏希亚科的底部，属于鳄鱼系始祖龙。在形态上与同时代相似的刺参和桑比亚可能是江豚科内的姊妹类群。我们的结果提高了对早期始龙之间先前缺乏约束的关系的分辨率，并提高了对几个关键的早期伪水母支系的系统发育支持水平。此外，他们还证伪了之前的假设，即达班人和桑比人不是始祖龙冠群的成员。Gracilisuchidae的识别为中三叠世冠始龙的快速系统发育多样化提供了进一步的支持。中国和阿根廷的细长脊椎动物分支的分离分布表明，早期的始龙分布在联合古陆的大部分或全部地区，尽管它们最初可能是动物群组合中相对罕见的成员。
The origin and early radiation of archosaurs and closely related taxa (Archosauriformes) during the Triassic was a critical event in the evolutionary history of tetrapods. This radiation led to the dinosaur-dominated ecosystems of the Jurassic and Cretaceous, and the high present-day archosaur diversity that includes around 10,000 bird and crocodylian species. The timing and dynamics of this evolutionary radiation are currently obscured by the poorly constrained phylogenetic positions of several key early archosauriform taxa, including several species from the Middle Triassic of Argentina (Gracilisuchus stipanicicorum) and China (Turfanosuchus dabanensis, Yonghesuchus sangbiensis). These species act as unstable ‘wildcards’ in morphological phylogenetic analyses, reducing phylogenetic resolution. We present new anatomical data for the type specimens of G. stipanicicorum, T. dabanensis, and Y. sangbiensis, and carry out a new morphological phylogenetic analysis of early archosaur relationships. Our results indicate that these three previously enigmatic taxa form a well-supported clade of Middle Triassic archosaurs that we refer to as Gracilisuchidae. Gracilisuchidae is placed basally within Suchia, among the pseudosuchian (crocodile-line) archosaurs. The approximately contemporaneous and morphologically similar G. stipanicicorum and Y. sangbiensis may be sister taxa within Gracilisuchidae. Our results provide increased resolution of the previously poorly constrained relationships of early archosaurs, with increased levels of phylogenetic support for several key early pseudosuchian clades. Moreover, they falsify previous hypotheses suggesting that T. dabanensis and Y. sangbiensis are not members of the archosaur crown group. The recognition of Gracilisuchidae provides further support for a rapid phylogenetic diversification of crown archosaurs by the Middle Triassic. The disjunct distribution of the gracilisuchid clade in China and Argentina demonstrates that early archosaurs were distributed over much or all of Pangaea although they may have initially been relatively rare members of faunal assemblages.
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影响因子：
3.7
作者：
Butler RJ;Brusatte SL;Reich M;Nesbitt SJ;Schoch RR;Hornung JJ
通讯作者：
Hornung JJ
DOI：
10.1098/rspb.2010.0508
发表时间：
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影响因子：
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作者：
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