Protoceratops

Chapter • Meet the dinosaur

Overview

Protoceratops andrewsi was a sheep-sized plant-eater with a bulky body, short limbs and a strikingly oversized head. The skull made up nearly a third of the animal's total length and ended in a sharp, parrot-like beak formed by the rostral bone, a structure unique to ceratopsians. At the back of the skull rose a bony neck frill whose size and shape varied a great deal between individuals. Unlike its famous relatives Triceratops and Styracosaurus, Protoceratops had no true horns, only low bosses above the nose and eyes. Its body was covered in scaly skin, and tall spines along the back and tail gave the tail a distinctive high, flattened profile. It walked on all fours on broad, heavy feet. Protoceratops was a low browser that used its beak to shear off tough, fibrous desert plants, which were then sliced and ground by tightly packed rows of teeth further back in the jaws. The fossil record points to a social animal: several specimens are often found together, including a cluster of fifteen juveniles buried at the same moment by a sandstorm or a collapsing dune. Measurements of the sclerotic rings in the eye sockets suggest the animal could be active by day as well as around dawn and dusk, a sensible strategy in a hot desert. Growth studies show that the frill expanded disproportionately as animals matured, which strongly suggests it served as a display and signalling structure rather than as armour. Eggs and nests are known from the same beds. In 2020, analysis of the eggshell showed that Protoceratops laid soft-shelled eggs, rather like modern turtles, which were probably buried in warm sand. Daily growth lines in the teeth of embryos have been used to estimate an incubation period of roughly three months, remarkably long compared with birds of similar size. The species was named in 1923 by Walter Granger and William King Gregory, based on material collected during the American Museum of Natural History's Central Asiatic Expeditions to Mongolia in 1922 and 1923. The species name honours the expedition leader, Roy Chapman Andrews. At Bayn Dzak, the Flaming Cliffs, hundreds of skeletons of every age were recovered, from hatchlings to fully grown adults, making Protoceratops one of the best-known dinosaurs of all and a key species for understanding how ceratopsians grew and evolved.

Chapter • Where it lived

Habitat

Protoceratops lived roughly 75 to 71 million years ago, during the Campanian age of the Late Cretaceous, in what is now southern Mongolia and adjacent northern China. Most fossils come from the Djadochta Formation at Bayn Dzak (the Flaming Cliffs) and Tugrikin Shire, with further material from Bayan Mandahu in Inner Mongolia. The landscape was an arid dune field with seasonal rains, temporary waterholes and sparse vegetation. Many skeletons lie in upright, lifelike postures within fine-grained sandstone, interpreted as rapid burial by collapsing dunes or violent sandstorms. Its neighbours included Velociraptor, Oviraptor, Pinacosaurus and the early mammal relative Zalambdalestes.

Chapter • Family life

Breeding

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy