AGE:
Late Cretaceous (Campanian), Djadokhta Formation, 75 million years ago

SIZE:
Embryos about 10cm long, adults up to 1.8 metres

MEANING OF NAME:
'First horned face'

PRONUNCIATION:
Pro-toe-CER-a-tops

CLASSIFICATION:
CERATOPSIA: Neoceratopsia; Protoceratopsidae

Protoceratops andrewsi is one of the best known dinosaurs ever.

Literally hundreds of individuals have been collected in central Asia, and sometimes this species makes up more than 80% of all the dinosaurs known from a site.

All stages of growth are known from unhatched eggs containing embryos to hatchlings to 'teenagers' to male and female adults. Because so many stages of life of this sheep-sized dinosaur are known, palaeontologists have been able to understand how the skeleton changed throughout the life of the individual (something quite rare to know about fossil animals).

It is typical for the young of many living land vertebrates to have a larger head relative to the remainder of the body than is seen in adults. Comparison between the two skeletons of Protoceratops andrewsi, the hatchelling and the adult shows that this species followed the same pattern.

Protoceratops seems to have lived in large groups, perhaps forming nesting colonies along the shores of ancient lakes and streams that lay in an otherwise arid landscape. The catastrophies that can occur in such an environment, such as flash floods or extended drought coupled with the natural instinct of these dinosaurs to congregate probably led to the unusual abundance of this group in the fossil record.

Although Protoceratops andrewsi is a neoceratopsian, a group of dinosaurs, which typically have horns, there were none on this species, just low bony knobs of bone on the skull.

The descendants of Protoceratops andrewsi probably emigrated from Asia to North America where they eventually gave rise to such well known dinosaurs as Triceratops., which does have horns. The expansion of bone at the back of the skull, or the 'frill' as it is commonly known, functioned to reorient the muscles that moved the lower jaw so they acted more efficiently. The frill may also have played a role similar to horns in antelope where they act to establish social dominance between individuals of a group and to help animals within a species recognise another of their species especially during breeding times.

The eggs and skeleton of Protoceratops andrewsi in The Great Russian Dinosaurs Exhibition illustrate the various stages of life that these animals went through.

As with many vertebrates as they grow, the proportions of the skeleton of the juvenile are different from those of the adult.