Scales helped reptiles conquer Earth. When did they first evolve?

Their footprints left copious footprints in the muddy floodplains of the Permian, leaving traces scattered across ancient sediments. But in one of these slabs of tracks, scientists discovered something more: the trace of an animal’s tail as it was dragged across the ground. Surprisingly, these tail prints come complete with scale impressions, and at 300 million years old, they are among the oldest impressions we have.

This may seem small, but it shows us that some of the hard skin structures needed for our ancestors to survive on land evolved much earlier than previously expected. paper This discovery, published in the journal Biology Letters last May, describes this discovery in detail.

A rare find

The special slab bearing these relics was discovered in 2020 in the Piaskowiec Czerwony quarry in Poland. Mining was halted to enable paleontologists to search the red sandstone rocks for fossils. Gabriela Kalabkova described climbing over a “huge pile of rubble” only to discover a large slab of fossil traces at the summit. And there, among one set of footprints, was something new.

She invited her colleagues to join her at the top of the pile. None of them had ever encountered this type of archaeological dig before, but they “quickly understood that it had to be a physical impression,” she explained to Ars.

Kalabkova is a paleontologist at the Moravian Museum. She and her colleagues are part of a joint effort by Polish, Czech and German scientists to study the Permian in Poland — a geological time period extending from 289.9 to 252 million years ago. The Piaskowiec Czerwony quarry is the world’s second largest producer of a particularly distinctive species of Permian track known as Ichniotherium cottae. (If you were asked to draw hands, you might come up with something that looks like Ichniotherium cottae. The five bulbous imprints of the numbers are almost cartoonish.)

Footprints and tail imprints are examples of archaeological excavations or trace fossils. As the name suggests, they are fossilized marks or traces left by animals during their lives. It is almost impossible to match the exact animal to its tracks, especially when no fossils of the body exist, so the tracks themselves are often given scientific names.

However, in this case, we may have identified the source, which is why the world’s leading location for these same trails is in neighboring Germany, where the amazing site is located. Promaker Not only did the site yield abundant Permian artifacts, but it also provided fossils of animals with what looked like feet match Publications. They belong to diadectimorphsfour-legged vertebrates (tetrapods) that were a distant predecessor to mammals.

Bromker also provided useful proof of the extremely rare tail drag found at the Piaskoek-Chervoni quarry. Two other known drag-tails associated with I. cottae tracks have been found there. They also have similar corncob-shaped scales.