A pair of Saharan predators were unveiled today – each similar in appearance but vastly different in hunting tactics.

Eocarcharia dinops (Fierce-eyed dawn shark) hunted like a great white. It had a jaw full of dagger-like teeth, hinting that it ripped into live prey, tore at limbs, and disabled the victim. Eocarcharia also sports a large bony eyebrow. The team suggests that this ridge of bone was used as a battering ram to slam against peers and vie for mating rights.

Eocarcharia (Credit: Todd Marshall, courtesy of Project Exploration)

Kryptops palaios (Old hidden face) feasted like a hyena. Quick on its two legs, it gnawed on flesh and ripped at carcasses. It had a short jaw of tiny teeth, which was better at wolfing down innards than nipping at a moving target. Kryptops' name comes from the spikes that lined its face.

Kryptops (Credit: Todd Marshall, courtesy of Project Exploration)

Both lived 100 million years ago in present day Niger and, at first glance, both resemble tyrannosaurs rex. But T. rex never made it to any of the southern continents. These two, and their cousins, were the massive carnivores of the lower lands. They rivaled the Suchomimus (the so-called Super Croc) for dominance and stalked the long-necked Nigersaurus (which sounds like a blacksploitation film) for food.

Eocarcharia and Kryptops (Credit: Todd Marshall, courtesy of Project Exploration)

If you want to read more about the dual find, paleontologists Paul Sereno of the University of Chicago and Stephen Brusatte of the University of Bristol posted their paper here.