When scientists found Protoceratops’ nests in the Mongolian desert, it was proof that dinosaurs laid eggs and that some lived in family groups or herds.
There have been dozens of skeletons of Protoceratops found, both adult and juvenile, and so the whole growth pattern is known. It was found by the expeditions to the Gobi Desert undertaken by the American Museum of Natural History in the 1920s. It seems to have lived in herds, and its remains are so abundant that it has been termed the “sheep of the Cretaceous”.
Protoceratops was a small dinosaur, only about the size of a large dog. Although it looked fierce, with its heavy head, sharp, beak-like mouth and large bony frill around its neck, Protoceratops ate only plants. It had a heavy, squat body, with a long, thick tail. Protoceratops walked on its four stumpy legs, but moved quite quickly when in danger.
Name: Protoceratops, meaning ‘before the horned heads’
Size: 1.8-2.5m long and 1m high
Food: tough leaves and plants
Lived: about 110-66 million years ago in Mongolia in the Late Cretaceous Period
Protoceratops is a heavy animal with short legs, a deep tail and a heavy head. Although a member of the horned dinosaurs, it does not have true horns. Two forms of adult are known, a lightweight form with a low frill, and a heavier form with a big frill and a bump on the snout where a horn would have been. These probably represent the two sexes, with the males having the heavier head.
There was a bony frill or shield around its neck, which grew bigger and broader as the dinosaur grew older. The frill protected the neck of Protoceratops from attack by carnivorous dinosaurs. Males also used their frills for display, to attract females at the beginning of the mating season. Their frills made them look intimidating, which helped to ward off rival males.
Protoceratops had large, strong muscles around its jaws. These helped it bite off tough leaves and woody plants with its hooked beak. It then sliced up the plants with its scissor-like teeth.
In 1922, a scientific expedition to the Gobi Desert in Mongolia unearthed nests of Protoceratops’ eggs. These contained the first dinosaur eggs ever found. The discovery proved for the first time that dinosaurs laid eggs. Until then, no-one knew if they laid eggs or gave birth to live young. As many as thirty eggs were found in one nest. It is unlikely that one female laid so many eggs at once, so scientists speculated that two or more Protoceratops females may have shared the same nest.
Several nests have been found close together. This seems to show that Protoceratops lived in family groups or small herds. Once the eggs had hatched safely, the babies which broke out of the shells were about 30cm long. The adult females brought food to the nests until their young had grown large enough to find it for themselves.
Skeletons of Protoceratops found in Mongolia range from tiny ones still inside the eggs to small babies and fully grown adults. Some of the adults vary slightly. They have differently shaped frills, for example. Scientists have suggested that this is because the males were bigger than the females, with larger heads, frills and crests.
Protoceratops had to guard its nests against predators such as Oviraptor, whose name means ‘egg-stealer’. Dinosaur eggs would have made an ideal meal for it. A fossilised Oviraptor skeleton, with its skull smashed in, was found above a nest of Protoceratops’ eggs. Perhaps an angry parent had killed it when it tried to rob the nest.