Early fish had rudimentary fingers, scientists find
The origins of fingers and toes in animals can be found in a fish-like creature that lived on Earth 385 million years ago, according to new study.
European scientists, writing in a study published Sunday in the British journal Nature, found evidence of rudimentary fingers in the fins of the transitional fish Panderichthys, overturning earlier research that suggested the development of digits didn't happen until millions of years later.
Prior research had suggested the first creatures to develop fingers were early tetrapods, the first group of four-legged animals and the ancestors to amphibians, reptiles, mammals and birds.
While it had been theorized that fingers and toes might have developed earlier from the radials of early fish fins, proof of this had been hard to come by, according to authors Catherine Boisvert and Per Ahlberg from Uppsala University in Sweden, and Elga Mark-Kurik from Tallinn University of Technology in Estonia.
Scientists had done genetic testing of zebrafish, a distant relative of the ancient coelacanth fish that were forerunners to tetrapods, but those tests couldn't find any of the genetic mechanisms that regulate limb development in terrestrial animals.
Previous studies had also looked at the fossilized fins of Panderichthys and found, on the surface, evidence for only two distinct parts to the portion of the fin farthest from the body, adding further doubt that the fish-like creature had the elements of fingers.
The new study looked deeper into a fossil recovered in Latvia to overturn this finding, using a computed tomography (CT) scan similar to those used in medical X-rays to find evidence of the finger-like structures.
Their findings confirmed that what were thought to be two bones on the end of the fin were in fact six bones, including four radials that hint at the future development of fingers.
"This was the key piece of the puzzle that confirms that rudimentary fingers were already present in ancestors of tetrapods," said Boisvert in a statement.