March 4, 2010 | 20
It was an ancient silesaur, which emerged 10 million years before true dinos did. And its unearthing in Tanzania—the first early dinosaur-like animal to be found in Africa—adds new detail to the sketchy understanding of the primitive Ornithodira lineage that would eventually produce T. rex and turkeys alike.
Described in the March 4 edition of Nature from the fossils of 14 individuals, the new species, Asilisaurus kongwe, was uncovered among fossils of ancient crocodiles, a group from which it had likely split recently (Scientific American is part of Nature Publishing Group). It lived some 10 million years before the first dinosaurs emerged and was likely an omnivore—revealing that plant-eating evolved not once, but at least three times in the Triassic: in Asilisaurus and two early dinosaur lineages.
The four-legged Asilisaurus would have measured one to three meters long and weighed in at about 10 to 30 kilograms. Despite its superficial similarities to the Dinosauria taxon, the researchers conclude in their paper that "all silesaurids lack classical dinosaurian character states."
"This goes to show that there are whole groups of animals out there that we’ve never even found evidence of that were very abundant during the Triassic," Sterling Nesbitt, a postdoctoral researcher at the Jackson School of Geosciences at the University of Texas at Austin and lead study author, said in a prepared statement. It also helps to put dinosaurs in context, he noted. "They were really only one of several large and distinct groups of animals that exploded in diversity in the Triassic, including silesaurs, pterosaurs, and several groups of crocodilian relatives."
Image of Asilisaurus kongwe courtesy of Marlene Hill Donnelly/FIeld Museum