African dino sheds light on Pangaea break-up

The discovery of a new fossil in Egypt overturns previous theories that by the end of their reign African dinosaurs were isolated by continental drift from their evolutionary cousins in Europe and Asia.

Unearthed by palaeontologists led by Hesham Sallam of Egypt’s Mansoura University, the fossil represents the first evidence of a new species of titanosaur – long-necked, plant-eating dinosaurs that were common across the world during the Cretaceous period, which stretched from 145 to 66 million years ago.

But while the titanosaurs in general were very common, the discovery of a north African representative constitutes an extremely rare event. The region lacks easily accessible, exposed rocky fossil beds similar to those located in the Gobi desert or the Rocky mountains, so late Cretaceous finds have been few and far between.

The new species, which was about the length of a school bus (and thus modest in size for a titanosaur) has been named Mansourasaurus shahinae.

“This is a key new dinosaur species, and a critical discovery for Egyptian and African palaeontology,” says co-author Eric Gorscak.

“Africa remains a giant question mark in terms of land-dwelling animals at the end of the Age of Dinosaurs. Mansourasaurus helps us address longstanding questions about Africa’s fossil record and paleobiology – what animals were living there, and to what other species were these animals most closely related?”

Answers to the second question have previously proved difficult to fathom. By the late Cretaceous, the super-continent of Pangaea had begun to split apart, with giant landmasses gradually moving into the configurations seen today.

As the land divided, animal and plant species were profoundly affected, with emergent stretches of water – small and vast – forming impenetrable barriers. This, inevitably, drove evolution, with species divided and forced along divergent adaptive paths.

What has been unclear, however, is the degree to which African species were cut off from those elsewhere. Since unearthing the skull, vertebrae, forelimb, hind foot and dermal plates that comprise Mansourasaurus, Sallam and colleagues have been able to fill in some of the blanks.

Analysing the bones, they were able to establish that the dinosaur was more closely related to other titanosaurs in Europe and Asia than to species found in southern Africa and South America.

“Africa’s last dinosaurs weren’t completely isolated, contrary to what some have proposed in the past,” says Gorscak. “There were still connections to Europe.”

He terms the fossil the “Holy Grail” of finds – a well preserved new species from towards the end of the age of dinosaurs.

With excavations in the area in which Mansourasaurus was found picking up pace, the researchers are confident that further finds will help flesh out both the biological and geological history of the Cretaceous.

Gorscak likens the discovery of Mansourasaurus to  the process to doing a jigsaw.

“it’s like finding an edge piece that you use to help figure out what the picture is, that you can build from,” he says. “Maybe even a corner piece.”

The research is published in the journal Nature Ecology and Evolution.