科研之友
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摘要
A broad sample of extant turtles possesses a series of paired bones in the neck that are situated between the cervical vertebrae. These paired bones were originally proposed to be cervical rib remnants, but have more recently been interpreted as vestiges of intercentra. Here, we document, for the first time, the neck development of a pleurodire turtle, Emydura subglobosa, and identify blastematous structures, which partially recapitulate the ribs and intercentra of the plesiomorphic tetrapod condition. We identify blastematous %26quot;bridges%26quot; between intercentra and the corresponding ribs, which we homologize with the vestiges visible in extant turtles and with the remnant parapophyseal articulation processes of the intercentra of some stem taxa. Only the unpaired, median part of the intercentrum of the atlas is retained in adult turtles, but intercentra are recapitulated along the entire vertebral column during development; they are embedded in the cervical myosepta and serve as attachment sites for neck musculature. We also identify two rib rudiments in the occipital region, which may indicate that at least two vertebrae are integrated into the cranium of turtles in particular, and of amniotes in general. (C) 2013. Published by The Company of Biologists Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.
- 出版日期2013-11-15
