The Second Titanosaurian (Dinosauria: Sauropoda) from the Middle Cretaceous Galula Formation, Southwestern Tanzania, with Remarks on African Titanosaurian Diversity
The Second Titanosaurian (Dinosauria: Sauropoda) from the Middle Cretaceous Galula Formation, Southwestern Tanzania, with Remarks on African Titanosaurian Diversity
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DOI：
10.1080/02724634.2017.1343250
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发表时间：
2017-07
影响因子：
1.4
通讯作者：
E. Gorscak;P. O’Connor;E. Roberts;N. Stevens
中科院分区：
文献类型：
--
作者：
E. Gorscak;P. O’Connor;E. Roberts;N. Stevens
摘要：白垩纪中晚期非洲大陆的古生物地理意义尚不清楚，部分原因是在这些时期对大部分大陆进行了不完整的采样。在坦桑尼亚西南部暴露的加卢拉组（Galula Formation）中加强的野外工作揭示了多种脊椎动物群，包括新型泰坦龙类Shingopana Songwensis，gen.等11 月，如本文所述。基于左角骨、颈椎骨、颈肋骨和背肋骨、左肱骨和部分左耻骨，Shingopana 的形态表明与南美晚白垩世风龙类泰坦龙类有亲缘关系。颈椎神经脊柱的球根状扩张与萨尔加多博尼塔龙、帕拉达索鲁姆上龙和价格三角龙的情况相似。 Shingopana 的背侧肋骨还具有近端前凸缘和后凸缘，以前被认为是超龙所独有的。此外，Shingopana 是通过颈椎中后部的棘突椎板分离来诊断的。简约性和未经校准的贝叶斯系统发育方法都支持辛格帕纳是第一个与风龙科密切相关的非洲泰坦龙类。与其他非洲泰坦巨龙类（例如同时存在的鲁克瓦泰坦双子龙和地理上邻近的马拉维龙）的比较表明，南部非洲的形态代表了不同的分类单元，而不是形成一个单系类群。此外，与具有代表性的北非形态相比，南部非洲形态与南美分支表现出更强的亲缘关系，这表明构造驱动的两块大陆的分离可能影响了整个白垩纪逐渐孤立的南部非洲动物群的发展。
ABSTRACT The paleobiogeographic significance of continental Africa during the middle and Late Cretaceous is not well understood, in part due to incomplete sampling from large portions of the landmass during these intervals. Intensified field efforts in the Galula Formation exposed in southwestern Tanzania have revealed a diverse vertebrate fauna, including the novel titanosaurian Shingopana songwensis, gen. et sp. nov., described herein. Based on a left angular, cervical vertebrae, cervical and dorsal ribs, a left humerus, and a partial left pubis, Shingopana exhibits morphology indicating affinities with the Late Cretaceous aeolosaurine titanosaurians of South America. The bulbous expansion of the cervical vertebral neural spine is similar to the condition in Bonitasaura salgadoi, Overosaurus paradasorum, and Trigonosaurus pricei. The dorsal ribs of Shingopana also present proximal anterior and posterior flanges that previously were proposed to be unique to Overosaurus. Furthermore, Shingopana is diagnosed by a divided spinoprezygapophyseal lamina in the middle-to-posterior cervical vertebrae. Parsimony and both uncalibrated and tip-dated Bayesian phylogenetic approaches support Shingopana as the first African titanosaurian that is closely related to aeolosaurines. Comparisons with other African titanosaurians, such as the co-occurring Rukwatitan bisepultus and geographically proximate Malawisaurus dixeyi, suggest that southern African forms represent diverse taxa rather than forming a monophyletic group. Moreover, southern African forms exhibit stronger affinities with South American clades than with representative northern African form, suggesting that tectonically driven separation of the two landmasses may have influenced the development of progressively isolated southern African faunas throughout the Cretaceous.