Fossils from Hayden Quarry in Ghost Ranch, New Mexico belonged to an extinct species that was neither a dinosaur nor a lizard. It belonged to a cross between a chameleon and an anteater called Drepanosaurus, which roamed Earth more than 200 million years ago.
Drepanosaurus was a reptile that had a common ancestry with lizards, crocodiles, and dinosaurs. Experts say that it had a massive claw in its second digit of its forelimb. It also had grasping feet and a claw-like structure at the tip of its tail.
Analysis of the 212-million-year-old Drepanosaurus arm fossils, which are now published in the journal Current Biology, reveal that the animal grew one to two feet long. the last Drepanosaurus fossil was found in northern Italy three decades ago but it was badly crushed.
“This animal stretches the bounds of what we think can evolve in the limbs of four-footed animals,” says the study’s first author Adam Pritchard, a postdoctoral researcher at Yale. “Ecologically, Drepanosaurus seems to be a sort of chameleon-anteater hybrid, which is really bizarre for the time. It possesses a totally unique forelimb.”
However, unlike four-limbed animals tetrapods, Drepanosaurus’s radius and crescent-shaped ulna bones are not parallel. Tetrapods’ forearms connect to a series or shorter wrist bones but Drepanosaurus’s wrist bones are longer than the radius.
These bones indicate that the claw of the extinct reptile was used to hook into insect nests. Its arm was used to tear open the nest, through a motion similar to how anteaters hook and dig their food.
The analysis show that tetrapods developed modern ecological roles over 200 million years ago
Collaborators for the study included researchers from the University of Utah, the Stony Brook University, the Dinosaur Institute at the Natural History Museum of Los Angeles County and the Virginia Polytechnic Institute and State University.