Journal of Vertebrate Paleontology ( IF 1.4 ) Pub Date : 2021-07-09 , DOI: 10.1080/02724634.2021.1928681 Voltaire D. Paes Neto 1 , Julia B. Desojo 2 , Ana C. B. Brust 1 , Ana M. Ribeiro 1, 3 , Cesar L. Schultz 1, 4 , Marina B. Soares 1, 5
ABSTRACT
The phylogenetic relationships of Pseudosuchia, the crocodile-line of Archosauria, are still poorly resolved, in part, due to the lack of crucial braincase information for several key taxa. Recently, erpetosuchids and ornithosuchids have been recovered as close relatives to Aetosauria, sharing several braincase features. Here we provide the description of the first braincase of the basal aetosaur Aetosauroides based on specimens from the Upper Triassic Candelária Sequence of Brazil. Our study revealed the presence of an exoccipital lateral ridge and a medial ridge on the supraoccipital (both shared with all aetosaurs and erpetosuchids, but absent in ornithosuchids) and an anterolateral exit for the internal carotids (shared with all aetosaurs and ornithosuchids, but not with erpetosuchids). Aetosauroides lacks a medial contact between the exoccipitals (shared with the aetosaurs Desmatosuchus smalli and Tecovasuchus) and possesses a single hypoglossal foramen (contrasting with Stagonolepis robertsoni and Desmatosuchus spurensis). It also differs from the putative Argentinian Aetosauroides (PVSJ 326) by the presence of a ridge connecting the basal tubera medially (contrasting also with all stagonolepidoideans) and by a bulbous and ventrolaterally recurved basipterygoid process (contrasting with Paratypothorax). These features show that the braincase of aetosaurs is suitable for providing further phylogenetic information and may contribute to resolving controversies within Pseudosuchia relationships.
中文翻译:
来自巴西上三叠统的基底龙龙 Aetosauroides scagliai(Archosauria:Pseudosuchia)的第一个脑壳
摘要
Pseudosuchia 的系统发育关系仍然没有得到很好的解决,部分原因是缺乏几个关键分类群的关键脑壳信息。最近,人们发现了 erpetosuchids 和 ornithosuchids 作为 Aetosauria 的近亲,共享几个脑壳特征。在这里,我们根据来自巴西上三叠纪坎德拉里亚层序的标本,提供了对基部棘龙Aetosauroides的第一个脑壳的描述。我们的研究揭示了在枕上存在一个外枕外侧脊和一个内侧脊(与所有的龙类和二齿鳄类共有,但在鸟鳄类中不存在)和颈内动脉的前外侧出口(与所有的棘龙和鸟鳄类共有,但不与erpetosuchids)。Aetosauroides的外枕骨之间缺乏内侧接触(与Aetosaurs smalli和Tecovasuchus 共享),并且具有单个舌下孔(与Stagonolepis robertsoni和Desmatosuchus splashensis形成对比)。它还与推定的阿根廷Aetosauroides (PVSJ 326) 的不同之处在于存在连接基底结节内侧的脊(也与所有 stagonolepidoideans 形成对比)和球状和腹外侧弯曲的 basipterygoid 过程(与Paratypothorax形成对比))。这些特征表明,龙类的脑壳适合提供进一步的系统发育信息,并可能有助于解决伪鳄类关系中的争议。