Friday, August 15, 2008

Horned Dinosaurs

Horned dinosaurs are known as Ceratopsids, or "horned faces". The smallest were about the size of a pig, and the largest bigger than an elephant. They lived during the Cretaceous Period (the last third of the age of dinosaurs), and were probably present during the event which made dinosaurs extinct. No complete skeleton of Triceratops has ever been found, but the numerous skulls throughout North America suggest that this was one of the most common animals of its time.

In addition to horns on its face, ceratopsids had a large bony frill that covered the neck. For many years it was believed that this frill protected the animal's neck from attack by large meat-eating dinosaurs. Since then, several frills have been found pierced by Tyrannosaurus Rex bite marks. It is now thought that the frill was used to intimidate rivals, or for display during contests for mates.

One of the earliest horned animals was Protoceratops, which lived in the Gobi Desert 85-80 million years ago. Arid conditions in the region have preserved some specimens extremely well, complete with eggs, nests, and internal organs intact. There are also specimens of infant and juvenile protoceratops in various stages of development, which have provided important insights into how dinosaurs changed as they grew.

This was one of the first horned dinosaurs, and it must have been successful since its ancestors were extremely numerous, with habitats stretching  from Asia to North America.

Protoceratops had bony bumps on its face rather than fully developed horns; and a relatively small and plain neck frill, compared to the large and elaborate frills seen in later ceratopsids.
When it hatched, it was only about 20 cm long. Fully grown, it was about the size of a modern pig. Since adults have frequently been found in the nesting grounds, there is considerable evidence that protoceratops protected its eggs and cared for its young.

Much larger was the most famous horned dinosaur, triceratops, which grew to 9 meters (30 feet) in length and weighed up to 6 tons. The skull had three prominent horns, one on the nose and one above each eye, which could have inflicted nasty wounds on an attacker. Its impressive neck frill could reach up to 2 meters (7 feet) in width: one of the largest and heaviest skulls of any land animal ever known.

Its body was barrel-shaped and its limbs extremely strong, to support the weight of its massive skull and armor. The teeth prove this animal was a plant-eater, and a lifestyle similar to modern rhinos is usually suggested: it probably spent its time eating plants, and defending itself with its horns when threatened. Its large size suggests it could not run very fast.

Many specimens have been found together, especially in Colorado and Wyoming. Large groups of its close relative, chasmosaurus, have been found in Canada. This suggests that the ceratopsids might have traveled in herds for mutual defense.
First discovered in 1889 by paleontologist Othniel Charles Marsh, parts of over 50 individual triceratops are now known.

There were more than 100 species of ceratopsids, including some which walked on two legs, and others which had as many as 20 horns.

For my previous posts on dinosaurs, click here.

For some good coffee table books for the dinosaur enthusiast, check out Dinosaurus, by Steve Parker, and National Geographic Dinosaurs, by Paul Barrett.

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