for National Geographic News
Neglected for 20 years on the dusty shelves of a South African university, paleontologists have re-discovered the 215-million-year-old fossils bones of one of the earliest giant dinosaurs.
The two-ton (1.8 metric ton) species of sauropod, previously unknown to science, is the oldest known ancestor to lumbering herbivorous giants such as the well-known brachiosaurs of the Jurassic.
The 215 million-year-old specimen, named Antetonitrus ingenipes, is significantly older than any previously known sauropod, a class of plant-eating dinosaurs with four legs and long necks. The new dino helps scientists to bridge a gap in their knowledge of where sauropods came from and how they evolved to be so large.
The fossil bones were first unearthed in 1981 on central South African farmland by veteran fossil hunter James Kitching. But the fossils were initially misidentified. Researchers cleaned the fossils and left them on a shelf at the Witwatersrand University's Bernard Price Institute for Palaeontological Research in Johannesburg (BPI).
It wasn't until 20 years later, when young Australian dinosaur researcher Adam Yates, visited the institute in 2001 that the blunder was realized.
"It didn't take me very long to realize their significance it was very exciting indeed," Yates told National Geographic News. "First there was the pure joy at seeing such beautifully preserved and relatively complete remains," he said. "Then the mounting thrill as it began to sink in that this creature was very advanced for its time and so much more like the giant sauropod dinosaurs of the Jurassic than any of its Triassic contemporaries."
The partial skeleton (minus its skull, neck, and most of its ribs) is all that remains of a juvenile sauropod. The giant would have weighed two ton (1.8 metric tons) or more in real life, said Yates, now based at the BPI. The animal would have measured eight to ten meters (26 to 33 feet) in lengthpossibly longer when full grownand two meters (6.5 feet) high at the hips.
The bones were found in sediments roughly dated to 220 to 215 million years ago, during the late Triassic period, the time between 251 and 200 million years ago that saw the dawning of the age of the dinosaurs.
The previous title holder for oldest sauropod, Isanosaurus, is more similar to its later relatives and provides less insight into the early evolution of the group than the new find. Isanosaurus was discovered in Thailand in sediments 10 to 15 million years more recent than those surrounding the new South African sauropod.
Four-foot's First Steps
Antetonitrus (pronounced ant-ee-tone-ite-rus) helps cement a gap between smaller primitive two-legged dinosaurs previously thought to be related to the well-known four-footed long-necked herbivores like the brontosaur. The new fossil fills in the time gap between the two groups. Antetonitrus appears to retain some of the more primitive features of two-legged dinosaurs while possessing the more advanced body shape of sauropods.
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