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The discovery of a 240-million-year-old dinosaur in southern Tanzania has led scientists to rethink their evolution. An almost complete skeleton of the species, Asilisaurus kongwe or “ancient lizard ancestor” was reconstructed using the remains of at least 14 other dinosaurs.
Asilisaurus lived in the Middle Triassic era about ten million years earlier than the oldest known dinosaurs and belonged to a sister group known as silesaurs. Scientists say that the relationship between dinosaurs and silesaurs was similar to that between humans and chimpanzees.
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.
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It was nearly 1m (3ft) to 3m long, weighed up to 30kg (66lb) and had triangular teeth with a beak-like tip to its lower jaw.
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 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.”
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.”
http://www.timesonline.co.uk/tol/news/science/biology_evolution/article7048800.ece
What the bleep do we know!? Co my tak naprawdę wiemy!?
