A cache of dinosaurs discovered in Niger may challenge our understanding of continental formation, US scientists have claimed this week.
Rugops may challenge our theory of continental formation
One of the dinosaurs - Rugops - was a wrinkle-faced carnivore, which lived about 95 million years ago.
Rugops had relations in South America, indicating Africa became a separate continent later than thought, some researchers believe.
The work is detailed in the Proceedings of the Royal Society of London.
First wrinkle face
Working in an area of the Sahara no bigger than a football pitch, Professor Paul Sereno and his team, from the University of Chicago, dug up more dinosaurs from the late Cretaceous Period than the total found in Africa before.
"It was like the Valley of the Kings," said Professor Sereno, "except the kings were dinosaurs."
This week Professor Sereno unveiled models of some of the dinosaurs his team found on its expedition to Niger four years ago. The most significant of these was the skull of Rugops primus, a peculiar-looking meat-eating dinosaur.
Professor Sereno says the find is a key piece of evidence supporting his theory that Africa broke off from the rest of the super-continent Gondwana only about 100 million years ago, rather than over 120 million years ago, as scientists have previously suggested.
Rugops was a carnivore about nine metres long
Rugops, whose name means "first wrinkle face", was about nine metres (30ft) long with sharp teeth and a snout probably adapted for scavenging carrion.
The most interesting thing about Rugops is its ancestry, according to Professor Sereno.
Rugops belonged to a group of southern dinosaurs called abelisaurids. Before Professor Sereno's discovery, abelisaurids from the same period had been found in South America, Madagascar and India, but not mainland Africa.
Along with evidence from the sea floor, the bones of the wrinkle-faced dinosaur suggest that narrow land bridges continued to link the southern continents as recently as 95 million years ago, Professor Sereno believes.
He added: "You cannot have very close counterparts on the other continents unless there was traffic."