Scientists have discovered an ancient dinosaur-like creature, that lived 10million years before the oldest known dinosaurs roamed Earth. They reconstructed an almost complete skeleton of a species called Asilisaurus kongwe from the remains of at least 14 individuals at a sing site in Tanzania. The 240-million-year-old African find has forced scientists to re-think what they know about dinosaur evolution.
Asilisaurus, whose name means ‘ancient lizard ancestor’ in Swahili and Greek, lived in the Middle Triassic era. Measuring three to 10 feet long and weighing up to 4st 7lbs, the creature was dinosaur-like in appearance but in fact belonged to a sister group known as silesaurs. The relationship between dinosaurs and silesaurs was similar to that between humans and chimpanzees, say scientists. Silesaurs and dinosaurs – as well as crocodiles and the flying pterosaurs – are believed to have shared a common ancestor dating back even further.
Scientists had expected the closest relatives of dinosaurs to been meat-eaters that walked on two legs. But Asilisaurus stood on four legs and was a vegetarian, or perhaps an omnivore that ate both plants and meat. The creature had triangular teeth and a lower jaw with a beak-like tip. Similar traits evolved independently in at least two branches of the dinosaur family tree, in animals that were originally carnivorous. Being able to eat plants may have opened up a broader range of habitats, experts believe.
Dr Randall Irmis, from the University of Utah in the US, one of the international team of scientists who described the find today in the journal Nature, said: ‘The crazy thing about this new dinosaur discovery is that it is so very different from what we all were expecting, especially the fact that it is herbivorous and walked on four legs.
‘We knew that there were a number of species from the Triassic that were similar to Asilisaurus, but we were only able to recognise that they formed this group called silesaurs.’
Detailed anatomical information gained from the Asilisaurus discovery filled in the gaps in knowledge about the animals, he said.
The fossils were found alongside those of a number of primitive crocodile-like creatures. Their presence together at the same time and place suggests that crocodile and dinosaur diversification was rapid and happened earlier than had been thought. Co-author Dr Sterling Nesbitt, from the University of Texas at Austin, said: “Everyone loves dinosaurs, but this new evidence suggests that they were really only one of several large and distinct groups of animals that exploded in diversity in the Triassic, including silesaurs, pterosaurs and several groups of crocodilian relatives.”