New research suggests that dinosaurs were around for longer than was previously thought. Some terrestrial animals reorganized in parts of the supercontinent, Pangea after the mass extinction.

Predecessors of the dinosaurs included plant-eating animals known as silesaurs, which are related to the dinos. Other animals that made it out of the chaos included dog-sized creatures such as the Asilisaurus and the Nyasasaurus parringtoni.

A total of seven expeditions in Tanzania, Zambia and Antarctica, looking for fossils led researchers to the findings of these four-legged animals. Of these four-legged species animals, before the mass extinction event, 35 percent dwelled in most of the studied areas. In those same areas spanning up to 1,600 miles, just 7 percent remained ten million years after the majority of other species died off.  Other surviving animals were a group that includes modern birds and crocodiles. The distant ancestors of mammals also survived, this group is known as Cynodonts.

As reported by Discovery news, "In Tanzania, the main silesaur that we find is called Asilisaurus kongwe. Asilisaurus was about the size of a medium dog, like a golden retriever, and they tended to have long thin limbs," Associate Curator of Paleomammalogy at the Field Museum of Natural History, Kenneth Angielczyk said.

With its 5-foot long tail, Nyasasaurusm, researchers speculate whether or not it can be classified as the oldest dinosaur or a relative of the dinosaur family. "Nyasasaurus is either the oldest known dinosaur or the closest known relative of dinosaurs, but we can't completely rule out either option because the material is rather fragmentary," Angielczyk said. The study and findings were published in the journal, Proceedings of the National Academy of Sciences.