An article published in the journal “Current Biology” describes the study of fossils of Drepanosaurus unguicaudatus, a reptile that lived in the Triassic period, about 212 million years ago. The discovery complete fossils of this animal in New Mexico allowed to carry out detailed exams which confirmed that it had very strong forelimbs with a huge claw and an anatomic conformation definitely out of the normal that surprised the paleontologists.

Drepanosaurus is part of a genus of reptiles recognized only in the early ’90s after the first specimen bones were discovered in Italy in 1979. That skeleton was in poor condition but in later years other specimens much better preserved were discovered not only in Italy but also in the USA. The adults of this species had an estimated length around half a meter, and probably lived on trees feeding on insects.

One feature noticed in Drepanosaurus is the particular anatomic conformation of its forelimbs. Usually tetrapods have parallel ulna and radius while in this reptile ulna assumed a crescent shape detached from the radius. The place of ulna was taken by a wrist bone. This conformation may have allowed the animal to stick its big claw into a nest of insects with a technique similar to that of today’s anteaters.

Other distinctive features of Drepanosaurus were its grasping feet and a sort of spur at the end of its long tail. They, too, could be explained if this reptile attacked insect nests for food because it could get anchored to the ground as it dug into them. This would be a really extreme specialization and the oldest one discovered so far.

In-depth study of these unique characteristics of Drepanosaurus were made possible thanks to tests such as micro-CT scan, which are increasingly used in the field of paleontology. Many Drepanosaurus fossils were well preserved three-dimensionally but were very fragile so any physical intervention on them would be really risky. The new technology prevents these problems.

The similarities with modern mammals such as anteaters suggest that in the Triassic there were already tetrapods with specialized ecological roles. In essence, at the time possibly there was already a complex ecosystem with tetrapods in which even extreme types of adaptations had evolved.