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X射线扫描真足蛇化石 解密史前蛇类之谜

时间:2016-11-07 来源:毒蛇网 作者:蛇迷 点击:0

   导读:x射线扫描真足蛇化石 解密史前蛇类之谜,史前蛇类到底有没有足,通过法国研究人员对一块真足蛇化石的扫描,让大家一致认为蛇类是无足动物发出疑问。真足蛇到底有没有?是蜥蜴进化出来的吗?下面我们来看看:

X射线扫描真足蛇化石 解密史前蛇类之谜
 
   法国研究人员日前通过先进的X光技术,对一块真足蛇化石进行了扫描。结果发现,这种蛇与现代的陆生蜥蜴十分类似,这一成果有助于科学家揭开蛇的起源之谜。
 
   该研究由法国自然历史博物馆和国家科研中心的古生物学家共同完成。研究人员在最新一期美国《古脊椎动物学报》上报告说,这块真足蛇化石是10年前在黎巴嫩被发现的,其藏身的古岩石距今已有9500万年历史。它身长50厘米,从表面上看只有一只脚,长约2厘米。研究人员利用欧洲同步辐射加速器对其进行了X光扫描,结果又发现了这只真足蛇的另一只脚。
 
   研究人员介绍说,这只脚之所以不易被察觉,是因为它在岩石中发生了异化,其脚踝部分仅有4块骨头,而且没有脚趾,这说明真足蛇的足部已在当时呈现退化的趋势。研究人员认为,这只真足蛇所处的年代正好是蛇类从有脚蜥蜴向无足动物进化的时期,因此具有很高的研究价值。
 
   科学界对于蛇的起源一直存在争议,有人认为,这种生物由陆生蜥蜴演变而来,另一些人则认为,蛇的祖先是生活在海洋中的蜥蜴。
 
   生物谷推荐原文出处:
 
   Journal of Vertebrate Paleontology,  DOI: 10.1080/02724634.2011.539650
 
   Three-dimensional pelvis and limb anatomy of the Cenomanian hind-limbed snake Eupodophis descouensi (Squamata, Ophidia) revealed by synchrotron-radiation computed laminography
 
   Alexandra Houssayea; Feng Xub; Lukas Helfenb; Vivian De Buffrnila; Tilo Baumbachb; Paul Tafforeauc
 
   Abstract
 
   Cretaceous marine hind-limbed snakes are considered to be key fossils for understanding the origin and evolution of snakes. In view of the rarity of such fossils, performing new analyses on described specimens using emerging, cutting-edge techniques should bring important new insights on these forms. We investigated the three-dimensional morphology and inner architecture of the pelvic girdle and hind-limb bones of the type specimen of Eupodophis descouensi Rage and Escuilli, 2000, one of the three taxa for which at least one hind-limb is known, using synchrotron-radiation computed laminography (SRCL), a recently developed non-destructive technique that overcomes some of the limitations of synchrotron microtomography for flat, laterally extended objects. This experiment allowed a virtual exhumation of the second, hidden leg of the specimen. The morphology and proportions of the regressed pelvic and hind-limb bones of Eupodophis resemble those of the hind-limbed snakes Pachyrhachis and Haasiophis. As in Haasiophis, four tarsals are observed in each limb, but there are no traces of metatarsals or phalanges. Moreover, despite the presence of osteosclerosis and pachyostosis in the vertebrae and the ribs of Eupodophis, the inner structure of its limb bones is devoid of these osseous specializations and displays a microanatomical organization similar to that of extant terrestrial lizards. This suggests that limb regression in Eupodophis was not due to a qualitative alteration of growth but, more likely, to a local decrease in growth rate or shortening of growth duration.
 
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