The authors of the scientific paper describing the two new dinosaur finds are Sereno, Jeffrey Wilson of the University of Michigan and Jack Conrad of the University of Chicago. The second new dinosaur species, named Spinostropheus gautieri, was found in Niger in the same 135-million-year-old rocks where Sereno's expeditions excavated the dinosaurs Jobaria and Afrovenator. The fossil is an articulated, or connected, spine of a dinosaur and represents an ancient relative of Rugops and other abelisaurids.
These finds provide fresh evidence about when Africa, Madagascar, South America and India finally split from each other as a result of continental drift. Before these discoveries, abelisaurids were virtually unknown on Africa, leading some to suggest that Africa had split off first from the southern landmass Gondwana, perhaps as early as 120 million years ago. The new fossils indicate that Africa and other southern continents that formed Gondwana separated and drifted apart over a narrow interval of time, about 100 million years ago.
Coauthor and team member Jeffrey Wilson, assistant professor at the University of Michigan, said, "Until the continents fully separated, dinosaurs like Rugops and other animals used narrow land bridges to colonize adjacent continents and roam within a few degrees of the South Pole."
The fossils were discovered on two separate expeditions that Sereno led to Niger, one in 1997 and the other in 2000, which have brought to light many new dinosaurs and the 40-foot-long crocodilian Sarcosuchus, also known as "SuperCroc."
Sereno recalls the day in 2000 when team member Hans Larsson, now an assistant professor at McGill University in Montreal, spotted a jawbone -- and then, about two feet away, the rest of the skull. "It was hard to see which end was the front, but we quickly realized we were looking at a brain case, and that it was probably an abelisaur -- a huge find," Sereno said.