Spinosaurus, Carcharodontosaurus, Giganotosaurus o Tyrannosaurus rex son some of the best known theropods. Now, a team of paleontologists has described new specimens of theropods, a group of dinosaurs that includes both modern birds and their closest non-avian dinosaur relatives, from the Late Cretaceous deposits of the Chinas River Valley in the Chilean from Patagonia.
An increasingly complete picture
There is no doubt that the fossil record is key to understanding life today and this latest research offers insight into the dinosaurs and birds that lived in the region during the Late Cretaceous.r, just before the mass extinction 66 million years ago which saw the demise of most of the dinosaurs.
Among the fossils are the first theropods recorded in Chile. The researchers’ findings include megaraptores giants with large sickle-shaped claws and birds of the group that also includes today’s modern species.
“The fauna of Patagonia that led to the mass extinction was really diverse”explained Sarah Davis, who completed this work as part of her doctoral studies with Professor Julia Clarke in the Department of Geological Sciences at the UT Jackson School of Geosciences. “You have large theropod carnivores and smaller carnivores, as well as these groups of birds that coexist alongside other reptiles and small mammals.”
Non-avian theropod dinosaurs were mostly carnivorous and include top predators in the food chain. The study shows that in prehistoric Patagonia, these predators included dinosaurs from two groups: Megaraptoridae and Unenlagiinae. At over 7.6 meters long, megaraptors were among the largest theropod dinosaurs in South America during the Late Cretaceous epoch.
Some researchers have suggested that the southern hemisphere faced less extreme or more gradual climate changes than the northern hemisphere after the asteroid impact. This may have made Patagonia and other places in the southern hemisphere a haven for birds and mammals and Other life forms that survived extinction.
“It remains to be seen how life made its way into that doomsday scenario and gave rise to our southern environments in South America, New Zealand and Australia. Here theropods are still present, no longer as dinosaurs as imposing as megaraptorids, but as the diverse variety of birds found in the forests, swamps and marshes of Patagonia, and in Antarctica and Australia”, the researchers conclude.
Reference: Sarah N. Davis, Sergio Soto-Acuña, Roy A. Fernandez, Jared Amudeo-Plaza, Marcelo A. Leppe, David Rubilar-Rogers, Alexander O. Vargas, Julia A. Clarke. New records of Theropoda from a Late Cretaceous (Campanian-Maastrichtian) locality in the Magallanes-Southern Basin, Patagonia, and insights into end Cretaceous theropod diversity. Journal of South American Earth Sciences, 2023; 122 : 104163 DOI : 10.1016/j.jsames.2022.104163