Chengdu Center of China Geological Survey, Chengdu, Sichuan, China.
Centre for Vertebrate Evolutionary Biology, Yunnan University, Kunming, Yunnan, China.
PeerJ. 2023 Mar 22;11:e14982. doi: 10.7717/peerj.14982. eCollection 2023.
Jurassic strata are widely distributed in the eastern part of Tibet Autonomous Region, and have yielded many dinosaur bones. However, none of these specimens has been studied extensively, and some remain unprepared. Here we provide a detailed description of some new sauropod material, including several cervical vertebrae and a nearly complete scapula, recovered from the Middle Jurassic of Chaya County, East Tibet. The cervical vertebrae have short centra that bear ventral midline keels, as in many non-neosauropod sauropods such as . Moreover, the cervical centra display deep lateral excavations, partitioned by a septum. The scapula has proximal and distal ends that are both expanded as in mamenchisaurids and neosauropods. However, relatively small body size and lack of fusion of neurocentral sutures in the cervical vertebrae suggest that the available material is from a juvenile, and the length of the cervical centra may have increased relative to the size of the rest of the skeleton in later ontogenetic stages. Phylogenetic analysis provides limited evidence that the new Tibetan sauropod specimen belongs to Eusauropoda, being more derived than , but is basal to Mamenchisauridae. The new material provides important information on the morphological transition between and mamenchisaurids, and extends the known biogeographic range of early-diverging sauropods in the Middle Jurassic of East Asia.
西藏自治区东部侏罗系地层分布广泛，产出了许多恐龙骨骼。然而，这些标本中没有一个得到过广泛研究，有些甚至还没有准备好。在这里，我们详细描述了一些来自西藏东部察雅县中侏罗世的新蜥脚类恐龙材料，包括几个颈椎和一个近乎完整的肩胛骨。这些颈椎的中心体较短，具有腹中线龙骨，这与许多非新蜥脚类蜥脚类恐龙（如 ）相似。此外，颈椎中心体显示出深的侧凹，由隔板分隔。肩胛骨的近端和远端都像马门溪龙类和新蜥脚类恐龙一样扩张。然而，颈椎相对较小的体型和神经中枢缝合线未融合表明，可用的材料来自幼年个体，并且在后期个体发育阶段，颈椎中心体的长度可能相对于骨骼的其余部分增加了。系统发育分析提供了有限的证据表明，新的西藏蜥脚类恐龙标本属于 Eusauropoda，比 更为衍生，但比马门溪龙科更为原始。新材料为 与马门溪龙类之间的形态过渡提供了重要信息，并扩展了东亚中侏罗世早期分化的蜥脚类恐龙的已知生物地理范围。
