瑞典乌普萨拉大学等机构科学家最新研究发现，3.8亿年前生活在海里的早期鱼类潘氏鱼已经长有原始脚趾。
长期以来，科学家普遍认为，最先长出简单脚趾的动物是能够呼吸空气的四足动物，它们在大约3.7亿年到3.7亿年前从海里爬到陆地上。
不过，乌普萨拉大学等机构的研究显示，潘氏鱼的鱼鳍里已经出现了原始脚趾。这种鱼生活在浅水里，长约1米，是一种过渡物种，与四足动物相比更类似于鱼类。
这一发现已经发表在最新一期英国《自然》（Nature）杂志上。论文作者之一的乌普萨拉大学研究人员佩尔·阿尔贝里说：“我们的研究表明，前肢和后肢在刚变形的鳍骨上就具有雏形，而非完全是从鳍骨上新长出来的。”（生物谷Bioon.com）
生物谷推荐原始出处：
Nature，doi:10.1038/nature07339，Catherine A. Boisvert，Per E. Ahlberg
The pectoral fin of Panderichthys and the origin of digits
atherine A. Boisvert1, Elga Mark-Kurik2 & Per E. Ahlberg1
1 Subdepartment of Evolutionary Organismal Biology, Department of Physiology and Developmental Biology, Evolutionary Biology Centre, Uppsala University, Norbyv?gen 18A, 752 36 Uppsala, Sweden
2 Institute of Geology at Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia
One of the identifying characteristics of tetrapods (limbed vertebrates) is the presence of fingers and toes. Whereas the proximal part of the tetrapod limb skeleton can easily be homologized with the paired fin skeletons of sarcopterygian (lobe-finned) fish, there has been much debate about the origin of digits. Early hypotheses1 interpreted digits as derivatives of fin radials, but during the 1990s the idea gained acceptance that digits are evolutionary novelties without direct equivalents in fish fin skeletons. This was partly based on developmental genetic data2, but also substantially on the pectoral fin skeleton of the elpistostegid (transitional fish/tetrapod)Panderichthys, which appeared to lack distal digit-like radials3. Here we present a CT scan study of an undisturbed pectoral fin of Panderichthysdemonstrating that the plate-like 'ulnare' of previous reconstructions is an artefact and that distal radials are in fact present. This distal portion is more tetrapod-like than that found in Tiktaalik 4 and, in combination with new data about fin development in basal actinopterygians5, sharks6 and lungfish7, makes a strong case for fingers not being a novelty of tetrapods but derived from pre-existing distal radials present in all sarcopterygian fish.
