Shape of Articular Surface of Crocodilian (Archosauria) Elbow Joints and Its Relevance to Sauropsids
Shape of Articular Surface of Crocodilian (Archosauria) Elbow Joints and Its Relevance to Sauropsids
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DOI：
10.1002/jmor.10846
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发表时间：
2010-07-01
影响因子：
1.5
通讯作者：
Suzuki, Daisuke
中科院分区：
文献类型：
--
作者：
Fujiwara, Shin-ichi;Taru, Hajime;Suzuki, Daisuke
确定已灭绝的祖龙肢骨关节面的面积和形状是困难的，因为死后分解的纤维组织和关节软骨提供了复杂的三维关节面。本研究的目的是描述6个鳄鱼标本手肘关节软骨的形状;比较其结构与4种鸟类，3个龟类，和5个鳞片;和比较钙化和关节软骨表面的形状在手肘关节的鳄鱼标本。鳄鱼肘关节软骨的形态与鸟类相似。肱骨有一鹰嘴窝，大约位于远端骨骺的中部，与关节面的伸肌侧边缘接壤。尺骨在其关节面的大约中间处具有突出的子叶间突，并将关节面分成桡侧和尺骨子叶。这将关节软骨分为屈肌部分上的关节面和伸肌部分上的鹰嘴。髁间突嵌入鹰嘴窝，限制肘关节伸展。恐龙和翼龙，在遗传学上属于鳄鱼目和鸟类，可能在它们的关节软骨上拥有类似的鹰嘴窝和子叶间突。虽然这些形状在骨骼上很难辨认，但它们在钙化软骨表面上的压痕提供了关节面伸肌边缘的重要指示。这反过来又有助于确定主龙手肘关节伸展的最大角度。J. Morphol. 271：883- 896，2010. (C)2010 Wiley-Liss，Inc.
The determination of area and shape of articular surfaces on the limb bones of extinct archosaurs is difficult because of postmortem decomposition of the fibrous tissue and articular cartilages that provide the complex three-dimensional joint surfaces in vivo. This study aims at describing the shape of the articular cartilages in the elbow joints of six crocodilian specimens; comparing its structure with that of four birds, three testudines, and five squamates; and comparing the shapes of the surfaces of the calcified and the articular cartilages in the elbow joints of an Alligator specimen. The shapes of the articular cartilages of crocodilian elbow joint are shown to resemble those of birds. The humerus possesses an olecranon fossa positioned approximately at the midportion of the distal epiphysis and bordering the margin of the extensor side of the articular surface. The ulna possesses a prominent intercotylar process at approximately the middle of its articular surface, and splits the surface into the radial and ulnar cotylae. This divides the articular cartilage into an articular surface on the flexor portion, and the olecranon on the extensor portion. The intercotylar process fits into the olecranon fossa to restrict elbow joint extension. Dinosaurs and pterosaurs, phylogenetically bracketed by Crocodylia and Ayes (birds), may have possessed a similar olecranon fossa and intercotylar process on their articular cartilages. Although these shapes are rarely recognizable on the bones, their impressions on the surfaces of the calcified cartilages provide an important indication of the extensor margin of the articular surfaces. This, in turn, helps to determine the maximum angle of extension of the elbow joint in archosaurs. J. Morphol. 271:883-896,2010. (C) 2010 Wiley-Liss, Inc.