A time-averaged artist’s interpretation of Patagonia during the Late Cretaceous. The animals pictured include non-avian dinosaurs, birds and other vertebrates that have been discovered in the fossil record of the region. Their specific identifications are as follows: ornithurine birds , Stegouros , Orretherium , Yaminuechelys , a megaraptorid , unenlagiines , and enantiornithine birds .
Since 2017, members of the Clarke lab, including graduate and undergraduate students, have joined scientific collaborators from Chile in Patagonia to collect fossils and build a record of ancient life from the region. Over the years, researchers have found abundant plant and animal fossils from before the asteroid strike that killed off the dinosaurs.
Reaching over 25 feet long, megaraptors were among the larger theropod dinosaurs in South America during the Late Cretaceous. The unenlagiines — a group with members that ranged from chicken-sized to over 10 feet tall — were probably covered with feathers, just like their close relative the velociraptor. The unenlagiinae fossils described in the study are the southernmost known instance of this dinosaur group.
The researchers identified the theropods from small fossil fragments; the dinosaurs mostly from teeth and toes, the birds from small bone pieces. Davis said that the enamel glinting on the dinosaur teeth helped with spotting them among the rocky terrain.