Sauropedia

A tribute to the 1993-1998 'Dinosaurs!' collection by Orbis Publishing Ltd.

Protoceratops May 17, 2011

Filed under: Ceratopsia — muzillu @ 3:50 pm

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.

Factbox

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.

 

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Triceratops May 13, 2011

Filed under: Ceratopsia — muzillu @ 9:15 am

Triceratops was a large, powerful ceratopsian, having one horn on its nose, which was small and stumpy, and one above each eye, which were up to a metre long. Triceratops probably used these long horns as weapons. It walked on all fours and had sturdy pillar-like legs. Its front legs were especially strong because they had to support the weight of its extremely heavy head.

Although Triceratops was the biggest of the long-frilled chasmosaurine ceratopsians (the living animal weighed something like 4.5 tonnes), its frill wasn’t as long as that of its relatives. It was more in the proportion of its short-frilled cousins, the centrosaurines. When it was discovered, it was only known from a pair of horn cores. However, the whole skulls were so solid that they began to turn up quite regularly as complete fossils. Over the years, so many different skulls of Triceratops have been unearthed that at one time there were 16 species attributed to the genus. These have now been combined, so that only the two given here are acknowledged, the common T. horridus and the bigger, but rarer, T. prorsus. Some authorities regard these as male and female T. horridus.

Factbox

Name: Triceratops, meaning ‘three-horned face’

Size: up to 9m long and 3m high

Food: all types of plants

Lived: 70-66 million years ago in the Late Cretaceous in North America

Triceratops is the biggest and best-known of all ceratopsians. Its three magnificent horns give it its name. The horns on the fossilised skulls are only cores – they would have been covered in horny sheaths that made them much bigger. The neck shield is massive, with no holes in it, and is bordered by little knobs of bone. The teeth are arranged to work as shears, and powered by strong jaw muscles.

Around Triceratops’ neck was a huge, bony frill which protected its shoulders and could withstand shattering blows from other dinosaurs. Although nobody really knows what colour dinosaurs were, some scientists think that Triceratops’ neck frill was brightly coloured. They believe that Triceratops was so well armed, it didn’t need to be a green or brown colour for camouflage, but had a brightly coloured frill to attract females.

Triceratops was a herbivore. It nipped off shoots and leaves with its bony parrot-like beak. It ground them up with rows of teeth at the back of its mouth. As the teeth wore down, new ones grew in their place.

On its massive head, Triceratops had three horns: above each eye and another on the end of its nose. It used the horns to defend itself from hunting dinosaurs, such as Tyrannosaurus. It also used the horns to fight other male Triceratops for the females, before mating.

The males probably fought each other to become leader of a herd and to attract females. They did not use their horns to wound. Instead, two males shoved and butted each other with their massive heads, locking horns in a bruising battle to prove which was the strongest. A Triceratops’ neck frill would protect its shoulders and body from a head-on attack by another male. Scientists have found damaged neck frills, which show that these fights between males were fierce enough to cause injuries.

Even dinosaurs as large as Tyrannosaurus would have thought twice about attacking Triceratops, because it could cause serious wounds by stabbing the enemy with its sharp horns. Triceratops was well-protected against attacking dinosaurs. Its bony neck frill was a good defence against sharp teeth and claws and it had tough skin with occasional hard knobs along its back.

Triceratops could charge at its enemies by sprinting at a top speed of 35km/h. A charge from this rhinoceros-like dinosaur would probably have been enough to scare off many predators.

 


 

Avaceratops May 12, 2011

Filed under: Ceratopsia — muzillu @ 4:37 pm

Although the ceratopsids are generally big animals, Avaceratops is quite small. It is known from an almost complete skeleton missing only the hip bones, much of the tail and, frustratingly, the roof of the skull including the horn cores. The skeleton found is not an adult, since most of the skull came apart before it fossilised, but it was almost fully grown when it died.

Factbox

NameAvaceratops, meaning ‘Ava’s horned face’ (from Ava Cole, the wife of the discoverer)

Size: 2.5m, but this was a juvenile. The grown animal was probably 4m.

Food: Low-growing plants

Lived: between 100 – 66 million years ago in the late Cretaceous Period, in North America

This small ceratopsid has a short frill that is quite thick. Like other centrosaurines, it has a short, deep snout, a powerful lower jaw with batteries of double-rooted shearing teeth, and a beak like that of a parrot. It is assumed that like other centrosaurines, it has a bigger horn on the nose than above the eyes. It may be a juvenile or subadult of some other genus such as Monoclinius.

Avaceratops was a herbivore. It chopped off the stems with its parrot beak-like mouth. Avaceratops then sliced up the woody parts of the plants with rows of sharp teeth at the back of its jaws.

It is possible that Avaceratops could run quite fast on its four well-muscled legs. As it ran, it balanced itself with its heavy tail which it held off the ground.

So far, only part of one skeleton of Avaceratops has been discovered. It was found in 1981 in Montana, USA. It was not named until 1988.

Some scientists think that these animals may have lived in large herds, roaming the North American plains.