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Elpistostege and the origin of the vertebrate hand. | LitMetric

Elpistostege and the origin of the vertebrate hand.

Nature

College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia.

Published: March 2020

AI Article Synopsis

  • The transformation from fishes to tetrapods marks a key point in vertebrate evolution, with fossil evidence from the Devonian period providing insights into this transition.
  • Recent findings have uncovered a well-preserved specimen of Elpistostege watsoni, noted for having the most complete skeletal structure of an elpistostegalian yet discovered.
  • Advanced imaging techniques show that Elpistostege's pectoral fin exhibits a skeletal arrangement similar to that of early tetrapods, suggesting that the anatomy of limbs evolved from aquatic features.

Article Abstract

The evolution of fishes to tetrapods (four-limbed vertebrates) was one of the most important transformations in vertebrate evolution. Hypotheses of tetrapod origins rely heavily on the anatomy of a few tetrapod-like fish fossils from the Middle and Late Devonian period (393-359 million years ago). These taxa-known as elpistostegalians-include Panderichthys, Elpistostege and Tiktaalik, none of which has yet revealed the complete skeletal anatomy of the pectoral fin. Here we report a 1.57-metre-long articulated specimen of Elpistostege watsoni from the Upper Devonian period of Canada, which represents-to our knowledge-the most complete elpistostegalian yet found. High-energy computed tomography reveals that the skeleton of the pectoral fin has four proximodistal rows of radials (two of which include branched carpals) as well as two distal rows that are organized as digits and putative digits. Despite this skeletal pattern (which represents the most tetrapod-like arrangement of bones found in a pectoral fin to date), the fin retains lepidotrichia (fin rays) distal to the radials. We suggest that the vertebrate hand arose primarily from a skeletal pattern buried within the fairly typical aquatic pectoral fin of elpistostegalians. Elpistostege is potentially the sister taxon of all other tetrapods, and its appendages further blur the line between fish and land vertebrates.

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Source
http://dx.doi.org/10.1038/s41586-020-2100-8DOI Listing

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