Sarcosuchus: Sarcosuchus was a prehistoric predator much like our modern alligator, living in swampsof the late Jurassic and early Cretaceous, the Sarcosuchus was an ambush animal; attacking anything that strayed to close to the murky swamps.  Sarcosuchus normally fed off Hypsolophadontids or scavenged, but it would occasionally kill a Spinosaur if on the verge of starvation.  In the Jurassic, it was able to survive underwater and re-emerge in the early cretaceous; if I were them,  I would have just died in the Jurassic, then I wouldn’t have had to be killed by a huge asteroid and the lack of food due to the smoke from volcanoes…Sheesh.