The ancient croc ancestor PancakeCroc (above, a computer-generated image of the head) was the "ultimate sit-and-wait predator," paleontologist Paul Sereno said in November 2009.

The creature would lie motionless, waiting "for something stupid" to swim into its rail-thin, 3-foot-long (0.9-meter-long) jaws (bottom), which were lined with rows of spiky teeth, Sereno said.

One of five newfound crocs that coexisted during the Cretaceous, PancakeCroc likely evolved its unique adaptations to reign over its own corner of the lush, river-carved plains of present-day Niger and Morocco.