Craniofacial morphology of Simosuchus clarki (Crocodyliformes: Notosuchia) from the Late Cretaceous of Madagascar
Craniofacial morphology of Simosuchus clarki (Crocodyliformes: Notosuchia) from the Late Cretaceous of Madagascar
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DOI：
10.1080/02724634.2010.532674
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发表时间：
2010-01-01
影响因子：
1.4
通讯作者：
Georgi, Justin A.
中科院分区：
文献类型：
--
作者：
Kley, Nathan J.;Sertich, Joseph J. W.;Georgi, Justin A.
克氏西莫鳄（Simosuchus clarki）是一种小型的、短鼻鳄形的能鳄目鳄形动物，产于马达加斯加晚白垩世。最初描述的基础上，一个单一的标本，包括一个非常完整和保存完好的头骨和下颌，S。目前已知的克拉基是从另外五个保存了部分颅面骨骼的标本中发现的。总的来说，这六个标本代表了除镫骨以外的头部骨骼的所有元素，从而使S。clarki是所有已知的基底中真蕨中保存最好和最完整的一种。在这份报告中，我们提供了一个详细的描述，整个头部骨骼的S。clarki，包括舌骨鳃器的一部分。两个最完整和保存完好的标本在几个大小和形状变量上有很大的不同（例如，突出，角度，和领域的平行），暗示性二型性。外部和内部的形态特征的评估表明，一个习惯性的头部姿势，其中眶前部分的真皮头骨屋顶向下倾斜45度的角度。功能和比较评估的喂养装置强烈表明，如果不是完全草食性饮食为主。S. clarki的研究结果与对陆地习性的颅后骨骼分析得出的解释一致，但目前关于穴居生活方式的工作假设不受支持。其头骨和下颌骨的非典型外观。clarki被至少45个自形特征的鉴定所强调，其中许多与大大缩短的鼻子有关。
Simosuchus clarki is a small, pug-nosed notosuchian crocodyliform from the Late Cretaceous of Madagascar. Originally described on the basis of a single specimen including a remarkably complete and well-preserved skull and lower jaw, S. clarki is now known from five additional specimens that preserve portions of the craniofacial skeleton. Collectively, these six specimens represent all elements of the head skeleton except the stapedes, thus making the craniofacial skeleton of S. clarki one of the best and most completely preserved among all known basal mesoeucrocodylians. In this report, we provide a detailed description of the entire head skeleton of S. clarki, including a portion of the hyobranchial apparatus. The two most complete and well-preserved specimens differ substantially in several size and shape variables (e.g., projections, angulations, and areas of ornamentation), suggestive of sexual dimorphism. Assessment of both external and internal morphological features indicates a habitual head posture in which the preorbital portion of the dermal skull roof was tilted downward at an angle of 45 degrees. Functional and comparative assessment of the feeding apparatus strongly indicates a predominantly if not exclusively herbivorous diet. Other features of the craniofacial skeleton of S. clarki are consistent with the interpretation developed from analysis of the postcranial skeleton of a terrestrial habitus, but the current working hypothesis of a burrowing lifestyle is not supported. The atypical appearance of the skull and lower jaw of S. clarki is underscored by the identification of at least 45 autapomorphic features, many of them related to the greatly foreshortened snout.