Paleontologists working in South Africa have found a new dinosaur species that may be the common ancestor of the sauropods, which were the longest vertebrate animals ever to walk the Earth and which are famous for their long-necks and whip tails.
The newly-discovered species, Aardonyx celestae, was bipedal but could drop down onto all four legs. Scientists say the creature had vertebral joints, straight femurs and flattened feet, which indicate that the skeleton supported a large amount of weight.
In addition, the vegetarian Aardonyx had a bone structure in its forearms that existed only in quadrapedal dinosaurs.
"The forearm bones of Aardonyx are beginning to show the interlocking position found in the giant sauropods," Matthew Bonan, a professor at Western Illinois University and a member of the team of scientists that made the discovery, said. "In other dinosaurs that are bipeds, that walk on their hind legs, you don't see that feature. You only see that in sauropods. Aardonyx may not have walked on all fours all the time, but it was certainly was capable of dropping down and walking on those forearms because it had the ability to resist the stress."
Another clue that the newly-discovered animal was an ancestor of the sauropods is that it had developed a skeletal structure that included jaws capable of opening very wide, allowing the dinosaur to 'bulk-browse," or consume large amounts of plant material in each bite. That adaptation became amplified later in the sauropods.
The location of the fossil discovery indicates that the new species lived in the early Jurassic period, about 195 million years ago, and that it most likely was a desert-dwelling animal that stayed close to an oasis.
A graduate student at South Africa's University of the Witwatersrand, Marc Blackbeard, stumbled across the bones of Aardonyx in a bone bed known to paleontologists for two decades.
The particular remains found were of a young individual, about 7 meters long.
The genus name of the dinosaur, which was found near the town of Senekal in South Africa's Northern Free State, means "Earth Claw." The first part of the genus name, Aard, is Afrikaans for "Earth," while the second part of the name, onyx, means "claw" in Greek.
Scientists gave the dinosaur its species name in honor of the scientist that prepared the fossil, according to a press release issued by the University of the Witwatersrand.
The announcement of the discovery was published Wednesday in Proceedings of the Royal Society B.
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