Two of the other types of animals — mammal-like reptiles and reptiles with parrot-like beaks — are believed to have died out by 228 million years ago. Also, paleontologists found no aetosaurs — small, armored reptilian plant eaters — that flourished beginning about 228 million years ago.
“The bottom line is, we think we have dinosaurs at least as old as those discovered before,” Flynn says. “It’s not conclusive, but we think there’s a reasonable argument to be made that they may well be the oldest.”
Up to this point, the oldest known dinosaurs are a species known as Herrerasaurus, dug up in Argentina and dated to be just under 228 million years old.
Interestingly, the Argentinean Herrerasaurus was a carnivorous theropod dinosaur, the group that would later include Tyrannosaurus rex and velociraptors. “Some of the major divisions in the dinosaurs actually happened early in their history,” Shubin says and suggests that paleontologists might be “missing more of the record than previously thought.”
Evolving to Mammals Also of interest are the mammal-like reptiles. “This is a group of things that are transitional, going from the big, cold-blooded reptiles to the small warm-blooded true mammals,” Flynn says.
Although fractured and incomplete, the wide range of fossils will help paint a more complete picture of this time.
Says Shubin: “They’re pulling out a giant jigsaw puzzle that they’re going to be figuring out over the next few years.”
Reuters contributed to this report.