Dino detectives solve ancient case of mistaken identity
Scientists have cleared up a 220 million-year old case of mistaken identity, rewriting Australia’s ancient dinosaur history in the process.
University of Queensland researchers, in collaboration with colleagues from overseas, have discovered a footprint found in an Ipswich coal mine 50 years ago was not made by a fearsome predator, but a more gentle plant-eating dinosaur.
UQ palaeontologist Anthony Romilio decided to reanalyse the footprints after looking at them with the benefit of 50 years of advancement in his field and realising they may have been misclassified.
‘‘They could only extract a certain amount of information from the footprints when they were first discovered and extrapolate from there,’’ Romilio said.
‘‘It’s only recently when we can make 3D models and share them with experts around the world that we can gain more insights from these.’’
It was initially thought that the dinosaur that made the footprint was a fearsome predator, and in fact it would have been the largest of its type anywhere in the world at the time. Palaeontologists estimated when it was first discovered that it would have had a body shape similar to the later Allosaurus, with a long tail, long hind legs, shorter arm-like front legs and a large head with a mouth full of razor-like teeth.
Under the new insight, a wholly different picture emerges of an animal with a much longer neck and smaller head, probably with longer front legs, belonging to a group known as prosauropods — the ancestors of the familiar longnecked, found-legged dinosaurs found millions of years later in the Jurassic and Cretaceous periods.
Romilio said it was possible this dinosaur was an ancestor of some of the later dinosaurs of that type discovered throughout Queensland dated to those periods, including Diamantinasaurus and the recentlydescribed Australotitan, the largest dinosaur ever discovered in Australia.
‘‘There is actually a gap of over 50 million years between this fossil and the earliest sauropod fossils in Australia,’’ he said.
‘‘So this establishes a much earlier time point in Australia’s dinosaur history for having those long-necked dinosaurs present.’’
The actual fossilised footprints are no longer accessible, because they were discovered on the ceiling of a coal mine in Ipswich which has long since been declared unsafe and shut.
Instead, Romilio and his colleagues relied on plaster casts taken by scientists in 1964 and held in the Queensland Museum’s collection.
Paper co-author Hendrik Klein, from Saurierwelt Palaontologisches Museum in Germany, said they created 3D models of the casts which could then be sent to colleagues around the world for further analysis.
‘‘The more we looked at the footprint and toe impression shapes and proportions, the less they resembled tracks made by predatory dinosaurs,’’ he said. ‘‘This monster dinosaur was definitely a much friendlier plant-eater.’’
The footprints would have been made when the dinosaur walked over marshy swampland of waterlogged plant debris in the Triassic period.
Over the millions of years that followed, silt would have filled the tracks and eventually turned to stone, while the plant matter beneath them turned to coal.
When the coal was eventually mined, the miners would have looked up to the cave ceiling and seen the tracks made by the animal.