Spiekman Stephan N F, Neenan James M, Fraser Nicholas C, Fernandez Vincent, Rieppel Olivier, Nosotti Stefania, Scheyer Torsten M
University of Zurich, Palaeontological Institute and Museum, Zurich, Switzerland.
Oxford University Museum of Natural History, Oxford, UK.
PeerJ. 2020 Nov 20;8:e10299. doi: 10.7717/peerj.10299. eCollection 2020.
The postcranial morphology of the extremely long-necked is well-known, but observations of skull morphology were previously limited due to compression of the known specimens. Here we provide a detailed description of the skull of PIMUZ T 2790, including a partial endocast and endosseous labyrinth, based on synchrotron microtomographic data, and compare its morphology to that of other early Archosauromorpha. In many features, such as the wide and flattened snout and the configuration of the temporal and palatal regions, differs strongly from other early archosauromorphs. The braincase possesses a combination of derived archosaur traits, such as the presence of a laterosphenoid and the ossification of the lateral wall of the braincase, but also differs from archosauriforms in the morphology of the ventral ramus of the opisthotic, the horizontal orientation of the parabasisphenoid, and the absence of a clearly defined crista prootica. was a ram-feeder that likely caught its prey through a laterally directed snapping bite. Although the cranial morphology of other archosauromorph lineages is relatively well-represented, the skulls of most tanystropheid taxa remain poorly understood due to compressed and often fragmentary specimens. The recent descriptions of the skulls of and now reveal a large cranial disparity in the clade, reflecting wide ecological diversity, and highlighting the importance of non-archosauriform Archosauromorpha to both terrestrial and aquatic ecosystems during the Triassic.
极长颈类的颅后形态是广为人知的，但由于已知标本受到挤压，此前对头骨形态的观察有限。在此，我们基于同步辐射显微断层扫描数据，对PIMUZ T 2790的头骨进行了详细描述，包括部分脑腔模型和骨内迷路，并将其形态与其他早期主龙形下纲动物进行了比较。在许多特征上，比如宽阔扁平的口鼻部以及颞部和腭部区域的结构，它与其他早期主龙形下纲动物有很大不同。脑壳具有一些衍生的主龙类特征，比如存在后蝶骨以及脑壳侧壁的骨化，但在耳后骨腹支的形态、副蝶骨的水平方向以及缺乏明确界定的前庭嵴等方面也与主龙形类不同。它是一种撕咬式捕食者，可能通过侧向快速咬击来捕获猎物。尽管其他主龙形下纲类群的颅骨形态有相对较好的呈现，但由于标本受到挤压且往往破碎，大多数长颈龙类分类单元的头骨仍了解甚少。最近对[具体物种1]和现在[具体物种2]头骨的描述揭示了该类群中存在巨大的颅骨差异，反映出广泛的生态多样性，并凸显了非主龙形类主龙形下纲动物在三叠纪对陆地和水生生态系统的重要性。
