Upside down: Cryobatrachus and the lydekkerinid record from Antarctica
Upside down: Cryobatrachus and the lydekkerinid record from Antarctica
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颠倒过来：南极洲的冰蜥蜴和lydekkerinid记录
DOI：
10.1017/jpa.2021.115
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发表时间：
2021
影响因子：
1.4
通讯作者：
Sidor, Christian A.
中科院分区：
文献类型：
--
作者：
Gee, Bryan M.;Makovicky, Peter J.;Sidor, Christian A.
Temnospondyl两栖动物在非海相三叠纪组合中很常见，包括南极洲的Fremouw组（下至中三叠纪）。Temnospondyls是最早从南极洲收集到的四足动物之一，但它们在弗雷莫组下部的记录一直很薄弱。其中一个分类群“Austrobrachyops jenseni”的模式标本只包含部分翼类，现在被认为属于双齿龙。第二个分类单元“Cryobatrachus kitchingi”的模式标本包括一个几乎完整的头骨，但该标本只暴露在腹部，由于其个体发育成熟度和解剖学的某些方面的不确定性，导致它被先前的工作人员指定为一种普通的duum。在这里，我们重新描述了C的全型。kitingi，一项通过层析分析增强的事业。大多数原始的解释和重建是无法证实的，有些是明显错误的。虽然最初被归类为lydekkerinid，但所谓的lydekkerinid特征被证明是没有根据的，或者不再诊断该家族。相反，我们发现了许多与高度不成熟的头龙共有的特征，头龙是一种大型的进化分支，记录在南极洲的上弗雷莫组和下三叠世的其他地方。此外，我们描述了一个新收集的来自Fremouw组下部的部分头骨，它代表了一个相对成熟的小身体个体，我们暂时称之为Lydekkerinidae；这个标本代表了迄今为止对南极洲lydekkerinid最可靠的鉴定。
Temnospondyl amphibians are common in non-marine Triassic assemblages, including in the Fremouw Formation (Lower to Middle Triassic) of Antarctica. Temnospondyls were among the first tetrapods to be collected from Antarctica, but their record from the lower Fremouw Formation has long been tenuous. One taxon, ‘Austrobrachyops jenseni,’ is represented by a type specimen comprising only a partial pterygoid, which is now thought to belong to a dicynodont. A second taxon, ‘Cryobatrachus kitchingi,’ is represented by a type specimen comprising a nearly complete skull, but the specimen is only exposed ventrally, and uncertainty over its ontogenetic maturity and some aspects of its anatomy has led it to be designated as a nomen dubium by previous workers. Here, we redescribe the holotype of ‘C. kitchingi,’ an undertaking that is augmented by tomographic analysis. Most of the original interpretations and reconstructions cannot be substantiated, and some are clearly erroneous. Although originally classified as a lydekkerinid, the purported lydekkerinid characteristics are shown to be unfounded or no longer diagnostic for the family. We instead identify numerous features shared with highly immature capitosaurs, a large-bodied clade documented in the upper Fremouw Formation of Antarctica and elsewhere in the Lower Triassic. Additionally, we describe a newly collected partial skull from the lower Fremouw Formation that represents a relatively mature, small-bodied individual, which we provisionally refer to Lydekkerinidae; this specimen represents the most confident identification of a lydekkerinid from Antarctica to date.