Sauropedia

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

Kentrosaurus January 30, 2012

Filed under: Thyreophora — muzillu @ 5:42 pm

A sharp spike on each shoulder of this dinosaur gave it extra protection from large predators. Kentrosaurus grazed on low-growing plants with its small head close to the ground. It walked on four chunky legs that carried its heavy body. Kentrosaurus lived at the same time as Stegosaurus, but was only about a quarter of its size.

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Name: Kentrosaurus, meaning ‘pointed lizard’

Size: 2.5m long and about 1m high

Food: low-growing plants

Lived: 150-140 million years ago in the Late Jurassic Period in Tanzania, East Africa

The nine pairs of plates on the neck and back are very much narrower than those of Stegosaurus, and the five pairs of spines run in a double row right down the tail. Near the front of its back, the spikes were quite flat. They became more narrow and pointed from its middle to the end of its tail. Another pair of spines projects sideways from the shoulders.

Unlike more advanced stegosaurs, it seems Kentrosaurus did not have ossicles across its body embedded in the skin. Kentrosaurus may have used its sharp spikes to defend itself rather like today’s porcupines do. The little skull contains a tiny brain with well-developed olfactory bulbs. This suggests Kentrosaurus had a very good sense of smell, which would have aided food gathering.

Kentrosaurus lived among some of the largest dinosaurs, the gigantic Giraffatitan and Dicraeosaurus, in what is now Tanzania, East Africa.

This stegosaur was excavated between 1909 and 1912 from the Tendaguru site by a team from Germany. Several hundred Kentrosaurus bones were found, suggesting that something like 70 individuals died there. The group find suggests that it may have been a herding animal. Two mounted skeletons were prepared for the Humboldt Museum in Berlin, Germany, but one was destroyed by bombing during World War II.

 

Huayangosaurus June 27, 2011

Filed under: Thyreophora — muzillu @ 3:36 pm

This primitive stegosaurid is known from complete adult skeletons found in the Dashanpu quarries, China, in the early 1980s. It was re-described in 1992. The arrangement of teeth, and the fact that its front legs are long for a stegosaurid put it so far from later stegosaurids that it is placed in a family of its own.

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Name: Huayangosaurus, meaning ‘lizard from Huayang’

Size: about 4m long and 1.5m high

Food: soft, juicy plants

Lived: 162-148 million years ago in the Middle Jurassic in China

Huayangosaurus has a double row of heart-shaped plates on the neck that are replaced by long, narrow, spine-like plates on the back. They become smaller on the tail, ending about half-way down. The tip of the tail is furnished with two pairs of spines. It had extra spikes on its shoulders, which would have been very off-putting to a predator. The skull has teeth at the front of the mouth – something that was lost in later stegosaurids – and there is a pair of horns near the eyes.

This stegosaur had many primitive features. For example, its skull had a small opening in front of each eye, and there was another small opening in each half of the lower jaw. Both of these openings closed off in later stegosaurs. At the front of its snout, Huayangosaurus had 14 teeth (seven on each side). Later stegosaurs did not have these teeth. Huayangosaurus had long front limbs three-quarters longer than the back limbs. Later stegosaurs had forelimbs that were much shorter. Finally, the armour plates that ran in two rows along the back of Huayangosaurus were more narrow and much thicker than the plates on the backs of its later relatives. All these features are clues to the stegosaurs’ place in the dinosaur family tree.

Huayangosaurus lived in a land of lakes, rivers, and lush vegetation. By looking at its teeth, scientists can tell it was a herbivore. Its spiky, upstanding armour plates and shoulder spines could have protected it from predators, but they could also have been for show, perhaps to attract a mate. They may also have been used to regulate its body temperature. The plates seem too thick, however, to have been very good for this. Certainly, the animal’s tail spikes would have kept its enemies away.

 

Hylaeosaurus June 20, 2011

Filed under: Thyreophora — muzillu @ 1:10 pm

Hylaeosaurus is the most obscure of the three animals used by Sir Richard Owen to first the new group Dinosauria, in 1842. The first Hylaeosaurus remains to be found were dug up by Gideon Mantell in 1832.

Gideon Mantell originally estimated that Hylaeosaurus was about 7.6 m long, or about half the size of the other two original dinosaurs, Iguanodon and Megalosaurus. Modern estimates range up to 6 metres in length.

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Name: Hylaeosaurus, meaning ‘woodland reptile’

Size: 4m long

Food: plants

Lived: about 130 million years ago in the Early Cretaceous Period in southern England

The fossils are entombed in a slab of limestone that can still be seen in London’s British Museum. Perhaps out of respect for the first generation of palaeontologists, no one has taken the trouble to actually prepare the fossil specimen, which seems to have been left by a dinosaur closely related to Polacanthus.

Only the front part of the dinosaur was found. Palaeontologists had to guess how the legs and body armour looked, but they are pretty certain that it looked like a long lizard with a cloak of sharply spiked armour running from its neck right down to the tip of its tail.

Hylaeosaurus was a slow-moving herbivore that nibbled ferns and other green plants for its food. If it was attacked, Hylaeosaurus was protected by its heavy armour and intimidating spikes.

It was a fairly typical nodosaur, with three long spines on its shoulder, two at the hips, and three rows of armour running down its back. It may also have had a row of plates down its tail. It had a long head, more like the head of a Nodosaurus than an Ankylosaurus and a beak, which it probably used to crop low-lying vegetation.

 

Stegosaurus May 14, 2011

Filed under: Thyreophora — muzillu @ 10:00 am

One spike of its spiked tail and Stegosaurus could cripple any predator that threatened it.

Stegosaurus had a small head, a thick, clumsy body and a spiky tail. Along its back were two rows of bony, diamond-shaped plates. Although it looked fierce, Stegosaurus ate mainly low-growing ferns and other plants. It lived in herds that grazed together.

Although S. armatus was the first Stegosaurus species to be found, S. stenops, found by Othniel Charles Marsh, is the more familiar species.

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Name: Stegosaurus, meaning ‘roof lizard’

Size: 7.5-9m long and 4m high

Food: low-growing ferns and other plants

Lived: about 140 million years ago in the Late Jurassic Period in North America

As well as the plates that Stegosaurus has along its back, it also has two pairs of spikes on the end of its tail to use as weapons. Recent studies show that these spikes stick out sideways. A mass of little bony ossicles protect the throat. The brain is the smallest, when compared with the bulk of the animal, for any dinosaur.

This dinosaur’s tail was long and used for balance, having very short front legs and much shorter back ones to support the weight of its body. It moved on all four legs, stumping heavily along. It could not walk or run very fast and was preyed on by fast-running, carnivorous dinosaurs, such as Allosaurus.

Its small head, which was about the size of a large dog’s, was close to the ground so Stegosaurus grazed mainly on low-growing plants. It had a weak jaw, and could chew only soft, leafy food.

Stegosaurus‘ spiky tail that was very thick and powerful, with bony plates all the way down. Stegosaurus may have used its tail to defend itself, and its young, against any carnivorous dinosaur which came within range.

The back plates were once thought to have been paired, but are now believed to have been in an alternating double row, with the largest plates at the hips, tapering in size towards the head. They may have been covered in horn and used for defence, or covered in skin and used as heat radiators.

Scientists have also suggested that the plates on Stegosaurus’ back may have been very brightly coloured. So the males probably used the plates to warn off other males in the herd and to attract the females at the start of the mating season.