How our hands were born from fish fins

A prehistoric fish with fingers: this is not science fiction, but the discovery of a team of paleontologists from theflinders universityAustralia, and theUniversity of Quebec at Rimouski, in Canada. This is the Elpistostege watsoni, a fossil fish found in 2010 across the Atlantic, in Miguasha National Park, Quebec.

1m57 long, it is the largest predator to have lived in a shallow marine area 380 million years ago. In their studypublished in the scientific journal Naturethe researchers reveal that this would be the missing evolutionary link in the transition between fish and tetrapods, these four-limbed vertebrates comprising mammals, birds, amphibians and reptiles.

Bones similar to those of the human arm

Thanks to the excellent state of preservation of the specimen, the researchers were able to analyze the pectoral fins in their integrity. They thus noted the presence of several bones that are also found in humans: the humerus (the arm), the radius and the ulna (the forearm), the carpus (the wrist) and phalanges organized into fingers.

The structuring of the vertebrate hand developed deep in evolution

“This is the very first time we have discovered fingers in a fish fin”rejoices John Long, professor of paleontology at Flinders University, in a article published on the institution’s website. The researcher compares these joints with the finger bones present in the hands of most animals.

“This finding pushes the origin of fingers in vertebrates back to the level of fish and tells us that the structure of the vertebrate hand was first developed deep in evolution, just before fish left the water.”explains John Long.

A “transitional fossil”

As Flinders University reminds us, the evolution of fish to tetrapods is one of the most important events in the history of life: it is with it that vertebrates were able to leave the water to conquer the earth. In this transition, the evolution of hands and feet was decisive.

“The origin of the fingers relates to the development of the fish’s ability to support its weight in shallow water or for short trips outdoors on land.explains Richard Cloutier, professor at the University of Quebec in Rimouski. The increasing number of small bones in the fin allow for more levels of flexibility to distribute its weight.” In short, if the Elpistostege watsoni is not necessarily our ancestor, it is the specimen that comes closest to a true “transitional fossil” between fish and tetrapods.