REDESCRIPTION AND PHYLOGENETIC AFFINITIES OF THE CAIMANINE EOCAIMAN CAVERNENSIS (CROCODYLIA, ALLIGATOROIDEA) FROM THE EOCENE OF ARGENTINA
REDESCRIPTION AND PHYLOGENETIC AFFINITIES OF THE CAIMANINE EOCAIMAN CAVERNENSIS (CROCODYLIA, ALLIGATOROIDEA) FROM THE EOCENE OF ARGENTINA
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DOI：
10.1002/spp2.1339
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发表时间：
2020-10-05
影响因子：
2.3
通讯作者：
Norell, Mark A.
中科院分区：
文献类型：
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作者：
Godoy, Pedro L.;Cidade, Giovanne M.;Norell, Mark A.
Caimaninae是为数不多的鳄鱼血统，仍然有生活的代表之一。今天，它的六个现存物种中的大多数仅限于南美洲和中美洲。然而，最近的发现揭示了一个更复杂的进化历史，化石记录比以前认为的更丰富，可能起源于北美。其中最古老的凯门鳄是Eocaiman cavernensis，来自阿根廷巴塔哥尼亚的始新世。它是由乔治G.辛普森在20世纪30年代，代表了第一个Caimanine报告的古近系。此后，E。在该类群的系统发育研究中，洞穴种是普遍存在的，但缺乏更详细的形态学描述和分类单元的修订。在这里，我们提出了一个重新评估E。cavernensis，基于第一手的检查和显微计算机断层扫描的正模标本，并重新解释其形态的不同方面。我们探讨了E. cavernensis和其他凯门鳄使用简约和贝叶斯推理方法。我们的研究结果提供了证据Caimaninae内的单系Eocaiman属，即使一些高度不完整的类群（包括同属Eocaiman itaboraiensis）代表显着的系统发育不稳定性的来源。我们还发现Culebrasuchus mesoamericanus作为姐妹所有其他凯门鳄和北美globidontans（即Brachychampsa和近亲）凯门鳄亚科以外。一个时间校准的树，使用一个简化的出生-死亡模型，显示了一个可能的坎帕尼亚起源的组（76.97 +/- 6.7马），这是年龄大于使用分子数据估计，并表明，最早的分支事件凯门鳄迅速发生，并跨越K-Pg边界。
Caimaninae is one of the few crocodylian lineages that still has living representatives. Today, most of its six extant species are restricted to South and Central America. However, recent discoveries have revealed a more complex evolutionary history, with a fossil record richer than previously thought and a possible North American origin. Among the oldest caimanines is Eocaiman cavernensis, from the Eocene of Patagonia, Argentina. It was described by George G. Simpson in the 1930s, representing the first caimanine reported for the Palaeogene. Since then, E. cavernensis has been ubiquitous in phylogenetic studies on the group, but a more detailed morphological description and revision of the taxon were lacking. Here, we present a reassessment of E. cavernensis, based on first-hand examination and micro-computed tomography of the holotype, and reinterpret different aspects of its morphology. We explore the phylogenetic affinities of E. cavernensis and other caimanines using parsimony and Bayesian inference approaches. Our results provide evidence for a monophyletic Eocaiman genus within Caimaninae, even though some highly incomplete taxa (including the congeneric Eocaiman itaboraiensis) represent significant sources of phylogenetic instability. We also found Culebrasuchus mesoamericanus as sister to all other caimanines and the North American globidontans (i.e. Brachychampsa and closer relatives) outside Caimaninae. A time-calibrated tree, obtained using a fossilized birth-death model, shows a possible Campanian origin for the group (76.97 +/- 6.7 Ma), which is older than the age estimated using molecular data, and suggests that the earliest cladogenetic events of caimanines took place rapidly and across the K-Pg boundary.