SCIENCE

On the Trail of an Unknown Dinosaur

Science Correspondent

May 27, 2009

Weird new dinosaurs and exquisltely-preserved fossils regularly make headlines, but these discoveries make up only a tiny portion of what paleontologists actually discover and work with. The majority of the fossil record is far more fragmentary, and while little scraps of bone might not cause journalists to start drooling they are just as important to understanding ancient life.

Take the case of a bit of femur, or thighbone, described in the latest issue of the Journal of Vertebrate Paleontology. Described by Catherine Forster, Andrew Farke, Jacob McCartney, William De Klerk and Callum Ross, the small bit of bone was recovered from rock in South Africa dating to about 140 million years ago. The fossils in that area are very fragmentary, it is not the sort of place you would expect to find an articulated skeleton, but there is enough there to know the area was once roamed by a diverse group of dinosaurs.

Among the collection of dinosaurs at the site was a small predatory coelurosaur called Nqwebasaurus (try saying that 10 times fast), but when scientists described it they found fragments from a second, unknown theropod dinosaur. This is the dinosaur the recently described femur came from, but what sort of dinosaur was it?

With so little to go on, the authors of the new paper were unsure of precisely what sort of dinosaur it might be, but it seemed to belong to the tetanurae, one of the great groups of theropod dinosaurs. There was another group of varied theropods during the time called the abelisauridae, but a number of characteristics of this fossil do not match that group. Instead it does seem to be a tetanuran, but more fossils will be needed to more fully understand what it is. For now this nameless fossil hints that there is much more yet to find, and I certainly hope that paleontologists can recover the rest of this tiny, ancient predator.