Kronosaurus was a short-necked plesiosaur, a meat-eating marine reptile 30 feet (9 m) long. It had four flippers, a huge head with strong jaws, and a short, pointed tail. The head was up to 9 feet (2.7 m) long, about 1/3 of the entire length of the body. It had rounded teeth at the back of the jaws which could crush shells and cephalopods (squid and octopi).
Kronosaurus was not a dinosaur, but a plesiosaur, another type of extinct reptile. Plesiosaurs may have evolved from the Nothosaurs or the Pistosaurus, a mid-Triassic reptile.
Pentaceratops was a rhinoceros-like dinosaur. It walked on four sturdy legs and had three horns on its face along with a large bony plate projecting from the back of its skull (a frill). One upward-pointing horn above its parrot-like beak and two longer, forward-pointing horns above its eyes probably provided protection from predators, and were possibly used in mating rivalry and rituals. It also had two enlarged, horn-like cheekbones that protruded from its face. It had a very large skull, 9.8 feet (3 m) long, with a very large, bony, scalloped, head frill. It has the largest-known skull ever found (for a land-dwelling animal).
Pentaceratops was about was up to 28 feet (8 m) long, roughly 10 feet tall (3 m), and weighed up to 8 tons. It had a short, pointed tail, a bulky body, column-like legs with hoof-like claws, and a bony, scalloped neck frill rimmed with bony points. It had a parrot-like beak, many cheek teeth, and powerful jaws. Pentaceratops hatched from eggs.
Stegoceras was a dome-headed, bipedal dinosaur. Its large head housed a thick skull, a relatively large brain, and large eyes. Its skull was about 3-4 inches (8 cm) thick. Males had thicker domes than females, and older Stegoceras had thicker domes than younger ones. Stegoceras had a fringe of horny knobs along the rear of its skull. It had short forelimbs and a large, stiff tail.
Stegoceras grew to be about 7 feet long (2.1 m) and 4 feet tall (1.2 m). This plant-eater weighed roughly 170 pounds (78 kg).