Study Suggests Earliest Dinosaurs May Have Roamed Sahara and Amazon

The oldest fossils date back about 230 million years and have been discovered further south, in places like Brazil, Argentina and Zimbabwe. "Dinosaurs are well studied, but we still don’t know where they come from," explains Joel Heath, a doctoral student in earth sciences at University College London (UCL) and lead author of the study.

According to the study, dinosaurs would have originated in warmer and drier environments like the Sahara. "So far, no dinosaur fossils have been found in the regions of Africa and South America that once formed this part of Gondwana," notes Joel Heath, stressing that "this could be because researchers have not yet found the right rocks, due to inaccessibility and lack of research efforts in these regions."

As part of the study, the researchers analyzed dinosaur fossils, evolutionary family trees and the geography of their time. According to its results, the first dinosaurs would have been much smaller than the giants. They were the size of a chicken or a dog, bipedal and probably omnivorous, feeding on both plants and meat.

According to the study, the appearance of dinosaurs would date back to 201 million years ago, probably in Gondwana. They would then have spread to other regions, including the southern Gondwana and the northern supercontinent of Laurasia, which would form Europe, Asia and North America. To confirm this hypothesis, the researchers tested three different evolutionary family trees, revealing the existence of the silesaurids, cousins of the dinosaurs, and considered as the ancestors of the ornithischians.