SKIRMISHER

Scientists have traced the origin of fingers and toes to fish-like creatures that roamed the seas 380 million years ago, according to a new study.

The findings, published today in the British-based science journal Nature, upend the prevailing theory on the evolution of digits.

It had long been assumed that the first creatures to develop primitive fingers were tetrapods, air-breathing animals that crawled from sea to land some 10 to 20 million years later.

The need to adapt to swampy marshlands and terra firma, the theory went, is what drove the gradual shift through natural selection from fish fins suitable only for swimming to weight-bearing limbs with articulated joints.

The study, however, reveals that rudimentary fingers were already present inside the fins of the shallow-water Panderichthys, a transitional species that was nonetheless more fish than tetrapod.

“What we have shown is that the hand and the foot emerge from pre-existing bits of the fin skeleton that were just reshaped, rather than being entirely new bits that were bolted onto the existing fin skeleton,” said co-author Per Ahlberg, a researcher at Uppsala University in Sweden.

The discovery did not come from a new archeological find but from the reexamination of existing fossils, he said.

Previous research, it turns out, had simply overlooked what was there.

“The problem is that all good specimens of Panderichtys come from one location” - a brick quarry in Latvia - “where the clay is almost exactly the same color as the bones,” he said.

“With a nice big bone, that is not a problem. But if you are interested in tiny, fragile bones at the outer end of the fin skeleton, it is nearly impossible to see what is going on.”