Cold capitosaurs and polar plagiosaurs: new temnospondyl records from the upper Fremouw Formation (Middle Triassic) of Antarctica
Cold capitosaurs and polar plagiosaurs: new temnospondyl records from the upper Fremouw Formation (Middle Triassic) of Antarctica
复制标题
寒冷的头龙和极地斜龙：来自南极洲弗雷莫组上部（中三叠世）的新的肢椎记录
DOI：
10.1080/02724634.2021.1998086
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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.;Sidor, Christian A.
南极洲的上弗雷莫组(中三叠世)保存了一系列不同的坦诺脊椎动物的记录，目前已发现三种。到目前为止，所有描述的材料都属于一个支系--头龙。我们的重新分析表明，关于底栖龙(雷龙)存在的粗略历史报告是错误的。在这里，我们报告了大量的来自上Fremuw组的大体颞骨脊椎的半下颌骨材料。所有七个标本，包括被认为是雷龙的历史材料，都展示了表明头龙亲缘关系的特征。这些标本在物质和概念上代表了已知的来自Fremuw组的TemnoSpindyl物质的显著扩展，尽管在没有骨骼重叠的情况下，它们不能与之前命名的三个南极物种中的任何一个确定地联系在一起。此外，所有标本都来自大型个体(即头骨长度超过70厘米)，这可能反映了高能通道滞后沉积所产生的攻击性过滤器，该过滤器是由上弗莱穆乌组化石地层的高能通道滞后沉积造成的。我们还报告了第一次出现的非头龙，属于斜龙的锁骨间。这只是三叠纪泛古大陆南部出现的第三次斜龙科，与之形成对比的是，这一支系在超大陆北部的记录要丰富得多，而南半球密切相关的短肢动物的记录也很丰富。再加上南极洲仍然没有吸龙，斜龙的记录暗示了世界性分支模式的分布存在细微差异，这些模式与目前尚未发现的生态和生理分化因素有关。
The upper Fremouw Formation (Middle Triassic) of Antarctica preserves a diverse record of temnospondyls, with three species currently recognized. To date, all of the described material belongs to a single clade, Capitosauria. Our reanalysis suggests that cursory historical reports suggesting the presence of a benthosuchid (Trematosauria) are in error. Here we report substantial amounts of hemimandibular material of large-bodied temnospondyls from the upper Fremouw Formation. All seven specimens, including the historic material attributed to Trematosauria, exhibit features indicative of capitosaurian affinities. These specimens represent a notable expansion in the physical and conceptual body of temnospondyl material known from the Fremouw Formation, although they cannot be definitively associated with any of the three previously named Antarctic species in the absence of skeletal overlap. In addition, all of the specimens come from large-bodied individuals (i.e., skull lengths exceeding 70 cm), which likely reflects a taphonomic filter created by the high-energy channel lag deposition of the fossiliferous horizon of the upper Fremouw Formation. We also report the first occurrence of a non-capitosaur, an interclavicle belonging to a plagiosaurid. This represents only the third occurrence of Plagiosauridae in southern Pangea during the Triassic, in contrast to a much richer record of this clade in northern parts of the supercontinent and a rich record of the closely related brachyopids in the southern hemisphere. Together with the continued absence of trematosaurs in Antarctica, the plagiosaurid record hints at nuances in the distribution of cosmopolitan clades patterns that are tied to presently unrecognized ecological and physiological differentiators.