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首页> 美国卫生研究院文献>Proceedings of the Royal Society B: Biological Sciences >Palaeoecology of triassic stem turtles sheds new light on turtle origins.
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Palaeoecology of triassic stem turtles sheds new light on turtle origins.

机译：三叠纪茎龟的古生态学为龟的起源提供了新的思路。

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Competing hypotheses of early turtle evolution contrast sharply in implying very different ecological settings-aquatic versus terrestrial-for the origin of turtles. We investigate the palaeoecology of extinct turtles by first demonstrating that the forelimbs of extant turtles faithfully reflect habitat preferences, with short-handed turtles being terrestrial and long-handed turtles being aquatic. We apply this metric to the two successive outgroups to all living turtles with forelimbs preserved, Proganochelys quenstedti and Palaeochersis talampayensis, to discover that these earliest turtle outgroups were decidedly terrestrial. We then plot the observed distribution of aquatic versus terrestrial habits among living turtles onto their hypothesized phylogenies. Both lines of evidence indicate that although the common ancestor of all living turtles was aquatic, the earliest turtles clearly lived in a terrestrial environment. Additional anatomical and sedimentological evidence favours these conclusions. The freshwater aquatic habitat preference so characteristic of living turtles cannot, consequently, be taken as positive evidence for an aquatic origin of turtles, but must rather be considered a convergence relative to other aquatic amniotes, including the marine sauropterygians to which turtles have sometimes been allied.
机译：龟早期进化的竞争假设在暗示龟起源方面的生态环境（水生和陆生）截然不同方面形成了鲜明的对比。我们首先通过证明现存海龟的前肢忠实地反映了栖息地的偏好，其中短手海龟是陆生而长手海龟是水生的，从而研究了灭绝海龟的古生态。我们将此度量标准应用于所有保留有前肢的活龟的两个连续的外群，即Proganochelys quenstedti和Palaeochersis talampayensis，以发现这些最早的外群无疑是陆生的。然后，我们将观察到的生活在龟中的水生与陆生习性分布绘制到假设的系统发育树上。两条证据都表明，尽管所有活龟的共同祖先都是水生动物，但最早的海龟显然生活在陆地环境中。其他解剖学和沉积学证据也支持这些结论。因此，不能将活水龟特有的淡水水生栖息地偏爱作为水龟水生起源的积极证据，而应被视为相对于其他水生羊水，包括有时与海龟同盟的海洋蜥脚类动物的汇聚点。 。

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