DINOSAURS, the giants of the prehistoric world, have been traced back to their humble origins after a series of spectacular fossil finds showing the dog-sized creatures from which they all evolved.
One of the finds is of an animal that lived about 245m years ago in southern Africa, several million years before any previously known sample.
Another is even more mysterious — a trail of footprints discovered in a Polish quarry, with all the features of dinosaur gait and dating from about 250m years ago.
“Dinosaurs reigned as the dominant large vertebrates on land for 135m years, diversifying into more than 1,000 species that ranged from animals weighing less than 1kg up to 70-tonne giants,” said Richard Butler, a palaeontologist at Birmingham University who worked on the Polish footprints. “Although most attention has been focused on the dinosaur extinction, arguably a more interesting question is how the dinosaurs evolved and became so successful in the first place.”
He will reveal his findings in a talk at the British Science Festival, held at Birmingham University this week. He says in a paper: “We found footprints . . . which shift the origin of the dinosaur lineage back to about 249m–251m years ago, which is 5m-9m years earlier than indicated by body fossils, earlier than demonstrated by previous footprint records, and just a few million years after the Permian/Triassic mass extinction of 252m years ago.”
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That extinction was caused by a massive volcanic eruption so large that it caused runaway global warming and poisoned the oceans.
By the time it was over, almost every animal species had been wiped out — but the predecessors of dinosaurs had survived.
Butler suggests that the creatures whose footprints he found appeared soon after that disaster and are best described as dinosauromorphs — meaning they are very similar to, but cannot yet be confirmed as having become, actual dinosaurs.
However, he expects more discoveries to make that clear, adding: “Recent discoveries have placed the Polish Triassic record as a key to understanding the ascent of dinosaurs.”
Other researchers have also found powerful evidence for dinosaurs evolving at about that time, albeit in other parts of the world. Nyasasaurus, the creature whose remains were found in Africa, has been dated to about 245m years ago.
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Paul Barrett of the Natural History Museum, London, who published a paper describing the creature as potentially “the oldest dinosaur”, said: “Back then, Earth’s continents were joined in one supercontinent we call Pangaea, so animals that evolved in one area could reach others.
“This animal was about the size of a medium-sized dog and would probably have been a carnivore. Dinosaurs are defined by anatomical features relating to their hips and hind legs, and this is on the cusp of what you call a dinosaur.”