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古脊椎动物Palaeospondylus的形态与四足动物的祖先相近
2022-05-29 14:06

日本东京大学Tatsuya Hirasawa团队近期取得重要工作进展,他们研究发现古脊椎动物Palaeospondylus的形态与四足动物的祖先相近。该项研究成果2022年5月25日在线发表于《自然》杂志上。

在这里,研究人员使用同步辐射 X 射线微计算机断层扫描来显示Palaeospondylus是一种肉鳍类动物,并且很可能是一种茎四足动物。Palaeospondylus的骨骼仅由内骨骼元素组成,其中发育有肥大的软骨细胞腔、类骨质和一小部分软骨膜骨。尽管完全没有牙齿和真皮骨骼,但Palaeospondylus的神经颅类似于茎四足类EusthenopteronPanderichthys的神经颅,系统发育分析将Palaeospondylus置于它们之间。由于Palaeospondylus的独特特征,例如软骨骨架和没有成对的附属物,存在于冠四足动物的幼虫中,他们的研究强调了四足动物根部出现了意想不到的异质性进化。

据介绍,来自中泥盆纪的Palaeospondylus gunni是最神秘的脊椎动物化石之一,自1890年在苏格兰发现以来,其系统发育的位置一直不清楚。化石的奇怪形态特征使其很难与已知的脊椎动物形态类型多样性进行比较。

附:英文原文

Title: Morphology of Palaeospondylus shows affinity to tetrapod ancestors

Author: Hirasawa, Tatsuya, Hu, Yuzhi, Uesugi, Kentaro, Hoshino, Masato, Manabe, Makoto, Kuratani, Shigeru

Issue&Volume: 2022-05-25

Abstract: Palaeospondylus gunni, from the Middle Devonian period, is one of the most enigmatic fossil vertebrates, and its phylogenetic position has remained unclear since its discovery in Scotland in 1890 (ref. 1). The fossil’s strange set of morphological features has made comparisons with known vertebrate morphotype diversity difficult. Here we use synchrotron radiation X-ray micro-computed tomography to show that Palaeospondylus was a sarcopterygian, and most probably a stem-tetrapod. The skeleton of Palaeospondylus consisted solely of endoskeletal elements in which hypertrophied chondrocyte cell lacunae, osteoids and a small fraction of perichondral bones developed. Despite the complete lack of teeth and dermal bones, the neurocranium of Palaeospondylus resembles those of stem-tetrapod Eusthenopteron2 and Panderichthys3, and phylogenetic analyses place Palaeospondylus in between them. Because the unique features of Palaeospondylus, such as the cartilaginous skeleton and the absence of paired appendages, are present in the larva of crown tetrapods, our study highlights an unanticipated heterochronic evolution at the root of tetrapods.

DOI: 10.1038/s41586-022-04781-3

Source: https://www.nature.com/articles/s41586-022-04781-3

Nature:《自然》,创刊于1869年。隶属于施普林格·自然出版集团,最新IF:69.504
官方网址:http://www.nature.com/
投稿链接:http://www.nature.com/authors/submit_manuscript.html


本期文章:《自然》:Online/在线发表

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