During the time of the dinosaurs, there were at least two crocs that grew to monstrous sizes worthy of a B-grade horror movie. Sarcosuchus, a roughly 110-million-year-old reptile, reached lengths of about 40 feet. Its narrow snout hints that it ate fish and relatively small fare. Another predator rivaled it in size: Deinosuchus, a roughly 40-foot-long creature that lived 80 to 73 million years ago and was a cousin of modern alligators. From tooth-marked remains, we know that this ambush predator ate dinosaurs.