School of environmental and Rural Science, University of New England, Armidale, NSW, Australia.
Australian Opal Centre, Lightning Ridge, NSW, Australia.
Sci Rep. 2020 Jan 29;10(1):1428. doi: 10.1038/s41598-020-57667-7.
The diversity of Australia's theropod fauna from the 'mid'-Cretaceous (Albian-Cenomanian) is distinctly biased towards the medium-sized megaraptorids, despite the preponderance of abelisauroids in the younger but latitudinally equivalent Patagonian theropod fauna. Here, we present new evidence for the presence of ceratosaurian, and specifically abelisauroid, theropods from the Cenomanian Griman Creek Formation of Lightning Ridge, New South Wales. A partial cervical vertebra is described that bears a mediolaterally concave ventral surface of the centrum delimited by sharp ventrolateral ridges that contact the parapophyses. Among theropods, this feature has been reported only in a cervical vertebra attributed to the noasaurid Noasaurus. We also reappraise evidence recently cited against the ceratosaurian interpretation of a recently described astragalocalcaneum from the upper Barremian-lower Aptian San Remo Member of the upper Strzelecki Group in Victoria. Inclusion of the Lightning Ridge cervical vertebra and Victorian astragalocalcaneum into a revised phylogenetic analysis focused on elucidating ceratosaurian affinities reveals support for placement of both specimens within Noasauridae, which among other characters is diagnosed by the presence of a medial eminence on the ascending process of the astragalus. The Lightning Ridge and Victorian specimens simultaneously represent the first noasaurids reported from Australia and the astragalocalcaneum is considered the earliest known example of a noasaurid in the world to date. The recognition of Australian noasaurids further indicates a more widespread Gondwanan distribution of the clade outside of South America, Madagascar and India consistent with the timing of the fragmentation of the supercontinent.
澳大利亚兽脚亚目动物的多样性从中期白垩世（阿尔比期-森诺曼期）就明显偏向于中型的巨盗龙类，尽管在年轻但纬度相当的巴塔哥尼亚兽脚亚目动物群中，阿贝力龙科占据主导地位。在这里，我们提出了新的证据，证明来自新南威尔士州闪电岭白垩纪格里曼克里克组的有角恐龙类，特别是阿贝力龙科的兽脚亚目动物的存在。描述了一个部分颈椎，其椎体的腹侧面呈中侧向凹陷，由尖锐的腹外侧脊限定，这些脊与椎弓根接触。在兽脚亚目动物中，这种特征仅在一个被归因于诺阿龙科的恐龙的颈椎上有报道。我们还重新评估了最近引用的证据，这些证据反对将最近描述的来自维多利亚州上斯特莱基组上巴雷米安阶-下阿普特阶圣雷莫段的跗跖骨和跟骨重新归类为角鼻龙类。将闪电岭颈椎和维多利亚州的跗跖骨和跟骨纳入修订后的系统发育分析中，重点阐明角鼻龙类的亲缘关系，为两个标本都支持放置在诺阿龙科内提供了支持，诺阿龙科除了其他特征外，还通过跗跖骨上升过程中的中嵴来诊断。闪电岭和维多利亚州的标本同时代表了澳大利亚报道的第一批诺阿龙类，而跗跖骨和跟骨被认为是迄今为止世界上最早的诺阿龙类化石。澳大利亚诺阿龙类的发现进一步表明，该分支在除了南美洲、马达加斯加和印度之外的冈瓦纳大陆有更广泛的分布，这与超级大陆的分裂时间一致。
