Palaeoecology of Triassic stem turtles sheds new light on turtle origins
Palaeoecology of Triassic stem turtles sheds new light on turtle origins
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DOI：
10.1098/rspb.2003.2523
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发表时间：
2004-01-07
影响因子：
4.7
通讯作者：
Gauthier, JA
中科院分区：
文献类型：
--
作者：
Joyce, WG;Gauthier, JA
早期海龟进化的相互竞争的假说在暗示海龟起源的生态环境水生与陆生非常不同方面形成了鲜明的对比。我们调查的古生态学灭绝的海龟，首先证明，现存的海龟的前肢忠实地反映栖息地的偏好，短手的海龟是陆地和长手的海龟是水生的。我们将这一指标应用于两个连续的外类群，所有的前肢保存，Proganochelys quenstedti和Palaeochersis talampayensis，发现这些最早的海龟外类群是明确的陆地。然后，我们绘制了观察到的分布水生与陆生的生活在海龟的生活习惯到他们的假设adaptogenies。这两条证据都表明，尽管所有现存海龟的共同祖先都是水生的，但最早的海龟显然生活在陆地环境中。更多的解剖学和沉积学证据支持这些结论。因此，对淡水水生栖息地的偏好不能被视为海龟水生起源的积极证据，而必须被视为相对于其他水生恐龙的趋同，包括海龟有时与之结盟的海洋蜥脚类。
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.