Early-bird dinosaur found in New Mexico
Palaeontologists delighted to discover 213m-year-old remains of feathered meat-eater that retain intact air sacs in their bones
Ian Sample, science correspondent
guardian.co.uk, Thursday 10 December 2009 19.00 GMT
A fleshed-out reconstruction shows the newly discovered Tawa hallae. Photograph: Jorge Gonzalez
The remains of a two-legged meat-eating predator that roamed the Earth at the dawn of dinosaurs have been uncovered in an ancient bone bed by fossil hunters.
The feathered beast, named Tawa hallae, was the size of a large dog and sported a long neck and tail, a slender snout, and sharp, curved teeth to catch and kill its prey.
Palaeontologists unearthed several skeletons belonging to Tawa hallae during an excavation at the Hayden quarry in northern New Mexico. The remains are more than 213m years old, placing the creature at the foot of tree of dinosaur evolution.
The species is one of the earliest known therapods, the group of dinosaurs that includes birds, velociraptors and Tyrannosaurus rex.
The most complete skeleton belongs to a juvenile that stood around 70cm tall at the hips and measured two metres from snout to tail.
The dinosaurs emerged in the late triassic period, around 230m years ago and became the dominant land-dwelling vertebrates for the next 160m years. "It's very rare to have known this much about a single dinosaur during the early time of dinosaur evolution," said Sterling Nesbitt, a palaeontologist at the University of Texas in Austin.
The dinosaur lived at a time when the world's land mass was a single vast supercontinent called Pangea. This later broke up into the separate continents we see today.
The animals' remains are in such good condition palaeontologists suspect they were buried very soon after dying. Examination of the fossils revealed air-filled sacs in the bones, a feature that links the dinosaurs with the evolution of birds much later.
"When we saw them, our jaws dropped. A lot of these theropods have really hollow bones, so when they get preserved, they get really crunched. But these were in almost perfect condition," Nesbitt said.
Analysis of the fossils from New Mexico suggest Tawa hallae may have originated in what is now South America and crossed Pangea to the region that is now North America, according to a report in the journal, Science.
"This new dinosaur Tawa hallae changes our understanding of the relationships of early dinosaurs and provides fantastic insight into the evolution of the skeleton of the first carnivorous dinosaurs," said Randall Irmis, a co-author on the study from the Utah Museum of Natural History.
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