By Jim Drury
Paleontologists say a 201-million-year-old dinosaur fossil found two years ago on a Welsh beach could offer vital clues to understanding the evolution from the late Triassic to the early Jurassic Period.
Dracoraptor hanigani has been classified as a new species. It's one of the oldest Jurassic dinosaurs ever found, and among the most complete specimens from the time period.
The early Jurassic period is crucial in the evolutionary history of dinosaurs. It followed an extinction event in the late Triassic era that wiped out more than half the species on Earth and may have created the subsequent global dominance of the dinosaurs, led by the likes of Tyrannosaurus rex and Velociraptor.
According to Cindy Howells, palaeontology curator at the National Museum of Wales where the fossil is on display, "it's an important find in the early Jurassic because at that time dinosaurs were just starting to diversify. They'd only just evolved, but the continents were in such a position it was favorable, the warm climate, and this is just when we were getting that evolution of different types of dinosaurs meat-eaters were just starting out on the journey they made toward the Velociraptor and Tyrannosaurus that we have in the Cretaceous period. So this little dinosaur is (one of) the very first along the line that led to the Velociraptor."
Species which successfully crossed over into the Jurassic age are believed by experts to hold clues to the diversification of dinosaurs into the many species that existed in the middle Jurassic period, some of which are the ancestors of birds.
Dracoraptor translates loosely as "dragon thief", while hanigani namechecks Rob and Nick Hanigan, the two fossil-hunting brothers who found the remains at Lavernock Point near the Welsh capital Cardiff.
Forty percent of the animal was preserved, including its skull, claws, teeth and foot bones. Due to the body's symmetry this has enabled the virtual recreation of 80 percent of the Dracoraptor.
"Because we've got so much of it we can fill in quite a lot of gaps in the evolution of this period and we can use it to compare with other dinosaurs that we've got in America and around the world and the comparison of its anatomy helps us understand how these dinosaurs moved, what they ate, how they lived."
The creature was relatively small, around two meters long from head to tail. A poster in the museum shows it to be many times smaller than the Tyrannosaurus rex, although paleontologists believe it to be a juvenile of indistinct age. Dracoraptor had short arms and large hands.
"This dinosaur was very small," said Howells. "It was an agile, meat eating creature with sharp teeth, sharp claws, able to move swiftly and grab its prey. We don't quite know what it would have eaten, but possibly small reptiles, small mammals, and possibly other dinosaurs as well. It was a bit like a medium sized dog, very slender, very long-tailed to help it balance as it moved."
Dating the creature was possible because the remains were found above the layers containing Triassic conodont fossils. Geochemical analysis of carbon isotopes can also be used to establish the Jurassic age of these rocks.
"We know this dinosaur is (was born) 200 million years ago, to within half a million years or so," said Howells. "The rocks down here we've been studying for quite a long time now and we can do direct comparisons with the ages of rocks in Austria, which is where the transition between the Triassic and the Jurassic boundaries is precisely located."
She added: "This dinosaur is really significant because we have very few meat-eating dinosaurs, (or) these Theropod dinosaurs from the very beginning of the Jurassic. This was a time just after a big extinction event had happened and the dinosaurs were just starting to diversify and expand in their range, so this is one of the first complete skeletons that we have from that age."
Paul Barrett, of the Natural History Museum in London, told New Scientist the dracoraptor is "one of the best preserved meat-eating dinosaurs from the early part of the Jurassic Period - not only in Europe, but globally." Barrett believes its discovery will be crucial in unlocking understanding how dinosaurs evolved in the wake of the major extinctions. OLUSSCIENCE Reuters US Online Report Science News 20160208T124638+0000