Most evidence indicates that the transition at the end of the Triassic, 205 million years ago, was a period of widespread extinction, leading to the ascendancy of dinosaurs during the Jurassic. The new Argentinean finds tell a different story: Vertebrate animals in the Upper Triassic were apparently more diverse in this region, showing a mixture Triassic and Jurassic forms that turns the extinction model on its head.
The new finds reported by Alcober include a prosauropod dinosaur, two ancestral crocodilians, and a mammal-like cynodont the size of a mouse. The latter group was considered extinct by this time period.
"These findings give us a broader idea of the diversity of terrestrial faunas at the end of the Triassic," said Alcober, principal investigator of Earthwatch Institute's Triassic Park project. He will also report his recent findings at the Earthwatch Annual Conference in Boston, on November 6.
"We are documenting with greater detail what happened at the end of the Triassic," added Alcober. "It seems that, in the southern part of the prehistoric supercontinent Pangea anyway, the Triassic-Jurassic extinction was not as catastrophic as apparently documented in the north."
The new dinosaur was an herbivore with a long neck and four stout legs, measuring no longer than four meters long, typical of prosauropods. What makes it unique is a foreshortened skull, like many later sauropods of the Jurassic and Cretaceous.