法國(guó)研究人員日前通過(guò)先進(jìn)的X光技術(shù),，對(duì)一塊真足蛇化石進(jìn)行了掃描,。結(jié)果發(fā)現(xiàn)，這種蛇與現(xiàn)代的陸生蜥蜴十分類(lèi)似,，這一成果有助于科學(xué)家揭開(kāi)蛇的起源之謎,。
該研究由法國(guó)自然歷史博物館和國(guó)家科研中心的古生物學(xué)家共同完成。研究人員在最新一期美國(guó)《古脊椎動(dòng)物學(xué)報(bào)》上報(bào)告說(shuō),，這塊真足蛇化石是10年前在黎巴嫩被發(fā)現(xiàn)的,，其藏身的古巖石距今已有9500萬(wàn)年歷史。它身長(zhǎng)50厘米,，從表面上看只有一只腳,，長(zhǎng)約2厘米。研究人員利用歐洲同步輻射加速器對(duì)其進(jìn)行了X光掃描,，結(jié)果又發(fā)現(xiàn)了這只真足蛇的另一只腳,。
研究人員介紹說(shuō)，這只腳之所以不易被察覺(jué),，是因?yàn)樗趲r石中發(fā)生了異化,，其腳踝部分僅有4塊骨頭，而且沒(méi)有腳趾,，這說(shuō)明真足蛇的足部已在當(dāng)時(shí)呈現(xiàn)退化的趨勢(shì),。研究人員認(rèn)為，這只真足蛇所處的年代正好是蛇類(lèi)從有腳蜥蜴向無(wú)足動(dòng)物進(jìn)化的時(shí)期,，因此具有很高的研究?jī)r(jià)值,。
科學(xué)界對(duì)于蛇的起源一直存在爭(zhēng)議，有人認(rèn)為,，這種生物由陸生蜥蜴演變而來(lái),，另一些人則認(rèn)為，蛇的祖先是生活在海洋中的蜥蜴,。（生物谷Bioon.com）
生物谷推薦原文出處：
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.
