National Geographic Explorer-in-Residence Paul Sereno excavates an Eocarcharia dinops jaw at the site of the dinosaur's discovery in the Sahara desert.

The newly revealed species give insights into southern-dwelling dinosaurs that rose to the top of the food chain during the Cretaceous period, 65 to 144 million years ago.

"What we've found are primitive members of the two groups of megacarnivorous dinosaurs that ruled the southern continents for 50 million years," co-author Stephen Brusatte said.

The two new dinosaurs, along with an even bigger predator, the fish-eating, sail-backed Suchomimus, represent a trio of meat-eating lineages that became dominant in Africa and possibly other southern landmasses, Sereno said.

(The National Geographic Society owns National Geographic News.)

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