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肺鱼或是第一个行走在陆地上的动物

2011/12/15 来源:Daily Mail
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芝加哥大学的科学家证实,这种奇怪的鱼具有能呼吸的肺,可以使用纤瘦的鳍肢“走路”。

肺鱼或是第一个行走在陆地上的动物

研究表明,小肺鱼的一小步可能成就生命进化的一次大跳跃。

芝加哥大学的科学家证实,这种奇怪的鱼具有能呼吸的肺,可以使用纤瘦的鳍肢“走路”。

一直传闻肺鱼具有行走能力,然而之前还没有近距离观察过。

肺鱼运动的新研究表明,它们通常会使用纤瘦的后鳍支撑起身体,并向前推动。

肺鱼展示出2种运动模式:一种是2个鳍肢一并使用的跳跃运动;另一种是鳍肢交互使用的“行走”运动。

之前,人们认为这种能力起源于早期的四足动物,它们是第一批有肢的陆栖动物。如今,科学家认为行走能力可能起源得更早,肺鱼或是行走动物的祖先。

美国的一项研究提出了一种可能——留下一些化石痕迹的是鱼而非陆地动物,长期以来人们认为它们是由早期四足动物留下的。

芝加哥大学的首席科学家Melina Hale博士称:“在大量的化石痕迹中动物交互使用行肢,这表明痕迹是由四足动物行走在坚固物体上留下的,然而,我们发现形态迥然不同的水生动物也能够留下非常相似的行动痕迹。”

Ancient Fish Takes a Walk

 

Behavioral evidence for the evolution of walking and bounding before terrestriality in sarcopterygian fishes

Heather M. King, Neil H. Shubin, Michael I. Coates and Melina E. Hale

Tetrapods evolved from sarcopterygian fishes in the Devonian and were the first vertebrates to colonize land. The locomotor component of this transition can be divided into four major events: terrestriality, the origins of digited limbs, solid substrate-based locomotion, and alternating gaits that use pelvic appendages as major propulsors. As the sister group to tetrapods, lungfish are a morphologically and phylogenetically relevant sarcopterygian taxon for understanding the order in which these events occurred. We found that a species of African lungfish (Protopterus annectens) uses a range of pelvic fin-driven, tetrapod-like gaits, including walking and bounding, in an aquatic environment, despite having a derived limb endoskeleton and primitively small, muscularly supported pelvis. Surprisingly, given these morphological traits, P. annectens also lifts its body clear of the substrate using its pelvic fins, an ability thought to be a tetrapod innovation. Our findings suggest that some fundamental features of tetrapod locomotion, including pelvic limb gait patterns and substrate association, probably arose in sarcopterygians before the origin of digited limbs or terrestriality. It follows that the attribution of some of the nondigited Devonian fossil trackways to limbed tetrapods may need to be revisited.

文献链接:http://www.pnas.org/content/early/2011/12/08/1118669109.abstract?sid=e734cf71-826c-47dc-9d18-80a2976b7e4a
 

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