Xiphactinus molossus belonged to a large family of fishes which inhabited the warm seas during Cretaceous time. The closest living relative of Xiphactinus is a long, slender, herring-like fish, with a saw-edge on the belly that lives today in the waters around the East Indies. Another distant relative found in streams of eastern Kansas is the mooneye.

This fish was carnivorous, feeding upon the smaller fishes. We may suppose that it rivalled the mosasaurs, the smaller ones at least, in strength and ferocity when we consider the size of the jaws and the powerful teeth.

The earliest known turtles are from the Triassic; they have undergone but slight changes since their first appearance. One of the more noted changes is the loss of the teeth. The origin of the turtles is still unknown. They are adapted to an aquatic, semiaquatic or terrestrial life. The marine turtles have paddle-like limbs while the giant terrestrial forms have pillar-like limbs. Turtles are carnivorous, omnivorous and herbivorous in feeding habits.

Near Los Angeles, California, there is an area known as Rancho La Brea, where asphalt arises from the bowels of the earth and reaches the surface to form small pools. This has been going on for many thousands of years — since late in the Ice Age at least.

The tar-seeps were often covered by a thin layer of water that tempted thirsty animals to wade out and drink. Once out into the tar-seep an animal would become stuck and die. The struggling animal would attract hungry predators or scavengers which in turn would wade out and become trapped as well.

The excavation of these pools has resulted in the finding of about 2,500 saber-toothed cat skulls or skeletons.