An international team of paleontologists has discovered what may be the world’s earliest dinosaur. According to the scientists, this creature, named Nyasasaurus parringtoni, roamed our planet about 245 million years ago.
The discovery, described in a paper in the journal Biology Letters, means that dinosaurs appeared about 10 – 15 million years earlier than fossils previously showed, originating in the Middle Triassic rather than in the Late Triassic period.
“If the newly named Nyasasaurus parringtoni is not the earliest dinosaur, then it is the closest relative found so far,” said lead author Dr Sterling Nesbitt of the University of Washington.
The scientific name of the new genus ‘Nyasasaurus’ combines the lake name Nyasa with the term ‘saurus’ for lizard. The late paleontologist Alan Charig, included as a co-author on the paper, named the specimen but never documented or published in a way that was formally recognized. The species was named ‘Parringtoni’ in honor of University of Cambridge’s Rex Parrington, who collected the specimens in the 1930s.
“For 150 years, people have been suggesting that there should be Middle Triassic dinosaurs, but all the evidence is ambiguous. Some scientists used fossilized footprints, but we now know that other animals from that time have a very similar foot. Other scientists pointed to a single dinosaur-like characteristic in a single bone, but that can be misleading because some characteristics evolved in a number of reptile groups and are not a result of a shared ancestry.”
The fossilized bones of N. parringtoni were collected in the 1930s from Tanzania, but it may not be correct to say dinosaurs originated in that country. When this dinosaur lived, the world’s continents were joined in the landmass called Pangaea. Tanzania would have been part of Southern Pangaea that included Africa, South America, Antarctica and Australia.
The researchers had one humerus – or upper arm bone – and six vertebrae to work with. They determined that the animal likely stood upright, measured 7 to 10 feet in length (2 to 3 meters), was as tall as 3 feet at the hip (1 meter) and may have weighed between 45 and 135 pounds (20 to 60 kilograms).
“The new findings place the early evolution of dinosaurs and dinosaur-like reptiles firmly in the southern continents,” said co-author Dr Paul Barrett of the Natural History Museum, London.
“Nyasasaurus and its age have important implications regardless of whether this taxon is a dinosaur or the closest relatives of dinosaurs,” Dr Nesbitt said. “It establishes that dinosaurs likely evolved earlier than previously expected and refutes the idea that dinosaur diversity burst onto the scene in the Late Triassic, a burst of diversification unseen in any other groups at that time.”
It now appears that dinosaurs were just part of a large diversification of archosaurs. Archosaurs were among the dominant land animals during the Triassic period 250 million to 200 million years ago and include dinosaurs, crocodiles and their kin.
“Dinosaurs are just part of this archosaur diversification, an explosion of new forms soon after the Permian extinction,” Dr Nesbitt said.
Bibliographic information: Sterling J. Nesbitt et al. The oldest dinosaur? A Middle Triassic dinosauriform from Tanzania. Biol. Lett. vol. 9, no. 1; doi: 10.1098/rsbl.2012.0949