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Current Affairs

Fish fossil reveals evolution of hand

Date: 19 March 2020 Tags: Miscellaneous

Issue

Researchers have discovered the fossil of a fish with finger-like digits in its fin that lived 380 million years ago, according to a new study.

 

Background

Until now, they had never found the complete skeleton of the pectoral fin, also known as the fore-fin. But researchers have discovered one of the most complete elpistostegalian fossils yet: a 5-foot-long fossilized fish in Miguasha, Quebec.

 

Details

  • Scientists believe it bridges the evolutionary gap between marine and land vertebrates as one of the oldest examples of a skeletal pattern resembling a hand.

  • About 374 million years ago, life on Earth began to transition out of the world's oceans to walk on land. This gave rise to the tetrapods, or four-limbed vertebrates, that included dinosaurs, land animals and eventually humans.

  • Scientists consider this transition from water to land, and animals acquiring hands and feet, to be one of the most significant events in the history of life on Earth.

  • Researchers have focused their efforts on tetrapod-like fish, called elpistostegalians, that lived between 359 and 393 million years ago during the Middle and Late Devonian periods.

  • CT scans of the skeleton revealed at least two skeletal digits that resembled fingers, as well as three more potential ones. They also found an arm, elbow, forearm and wrist attached to the finger-like digits.

  • All of them were still contained within a fin ray, or webbed flipper-like appendage, but the researchers believe it's the missing link between fish fins and vertebrate hands.

  • To date, this skeletal arrangement is the most similar to previously found tetrapods. And the fact that it was located in the fore-fin suggests it was more like a hand.

  • The origin of digits relates to developing the capability for the fish to support its weight in shallow water or for short trips out on land.

  • Elpistostege watsoni, as the fish has been named, would have been the largest predator dominating Quebec's shallow marine and estuary habitat 380 million years ago. Sharp fangs helped it snack on other large fish, whose fossils were found in the same area.

  • This finding pushes back the origin of digits in vertebrates to the fish level, and tells us that the patterning for the vertebrate hand was first developed deep in evolution, just before fishes left the water.