Scientists Say They Found Earth's Oldest Dinosaur Nyasasaurus parringtoni lived in the Middle Triassic period By Evann Gastaldo, Newser Staff Posted Dec 5, 2012 7:15 AM CST 72 comments Comments An artist's rendering of the Nyasasaurus, believed to have lived some 245 million years ago. (Mark Witton/Natural History Museum) (Newser) – Scientists studying fossilized bones originally discovered in Tanzania in the 1930s may have revealed Earth's oldest known dinosaur, LiveScience reports. Nyasasaurus parringtoni lived between 240 million and 245 million years ago, some 10 million to 15 million years earlier than any other dinosaurs previously discovered. Researchers stopped short of calling the Nyasasaurus the earliest dinosaur, because just six vertebrae and an upper arm bone are available to study, but numerous clues indicate the beast is, in fact, a dinosaur. "There was this big gap in the fossil record where dinosaurs should've been present and this fossil neatly fills that gap," the study co-author tells the BBC. Paleontologists have long believed dinosaurs existed in the Middle Triassic period, the era from which this fossil dates. If it is indeed a dinosaur, this fossil shows that dinosaurs started out "as a very insignificant group of reptiles" before exploding into the dominant life form on Earth millions of years later, the co-author says. Nyasasaurus probably stood upright and was seven to 10 feet long.