Sauropedia

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

Diplodocus January 27, 2012

Filed under: Sauropoda — muzillu @ 2:54 pm

The familiar long, low sauropod is known as Diplodocus. It is well-known from the many casts of the graceful skeleton of D. carnegii, the second species to be found. The casts, which appear in museums throughout the world, were excavated, reproduced and donated with finance provided by the Scottish-American steel magnate Andrew Carnegie in the early years of the 20th century.

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Name: Diplodocus, meaning ‘double beam’

Size: 27m (up to 40m in the case of D. hallorum) long and 3.6m high

Food: plants and leaves from trees

Lived: 150-138 million years ago in the Late Jurassic Period in North America

When humans walk, the movement of the ankles make the body move up and down. For sauropods like Diplodocus, any movement of their heavy bodies used up a lot of energy. Fossilised footprints show that sauropods had broad, round feet like an elephant’s, with short stubby toes.

A sort of wedge may have raised Diplodocus’ toes from the ground, just like the heel of a shoe. This meant that muscles did not have to work so hard to support the dinosaur’s body as it walked.

From its tiny head to the tip of its enormous tail, Diplodocus had a long line of bones called vertebrae. Its neck had 15, its back 10, and its tail about 70.

The neck and tail are finely balanced and as a result, Diplodocus could probably have raised itself on to its hind legs to reach high into the trees. The wear on the teeth shows that it could browse high in the treetops or among the undergrowth. Finds in the 1990s have led American palaeontologist Steven Czerkas to suggest that there may have been a row of horny spines down the neck, back and tail.

Diplodocus was built rather like a suspension bridge, with its front and back legs acting like twin towers. On an actual bridge, cables support the road that runs between the towers. Diplodocus’ long backbone was supported by muscles. So that the neck and tail could move easily, a tendon probably ran along the length of its backbone.

Diplodocus could fight off predators with its powerful whiplash tail, or rear up on its back legs using its tail as support. This freed the dinosaur’s massive front legs for defence. A large, curved claw on the inner toe could also be used as a sharp weapon.

Diplodocus’ neck was not as long as that of its Chinese cousin, Mamenchisaurus. Compared to the latter’s neck, which was 11m long, Diplodocus’neck was ‘only’ 7.5m long and its enormous weight was balanced by a long tail, which stopped the giant from tipping over. The bones that were hidden beneath Diplodocus’ skin and muscle were designed for strength and support, rather than speed.

In 2004, a presentation at the annual conference of the Geological Society of America made a case for Seismosaurus being a junior synonym of Diplodocus. This was followed by a much more detailed publication in 2006, which not only renamed Seismosaurus as Diplodocus hallorum, but also speculated that it could prove to be the same as D. longus.

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Massospondylus January 25, 2012

Filed under: Sauropoda — muzillu @ 12:04 pm

Massospondylus was one of the first herbivorous dinosaurs to appear on land. It had a small head and a long neck and tail. By tilting back on its hind legs, it could reach shoots and leaves at the top of tall trees.

The first Massospondylus specimen to be found consisted of a few broken vertebrae shipped to Sir Richard Owen, in London, from South Africa in 1854. Since then, the skeletons of more than 80 individuals have been found across southern Africa. There has even been a nest of six eggs found that have been attributed to Massospondylus. Another possible specimen has been found in Arizona, which may indicate that this was a very widespread animal.

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Name: Massospondylus, meaning ‘massive vertebra’

Size: 4m long

Food: plants and leaves from trees

Lived: about 200-180 million years ago in the Early Jurassic Period in southern Africa and North America

Massospondylus‘ teeth are large, some serrated and some flat. It is usually shown as a much more slender animal than other prosauropods of the same size. It has five fingers, but the fourth and fifth are very small. The huge, clawed first finger could be curved over, thumb-wise, across the second and third, making this a versatile hand.

When this dinosaur was discovered, small pebbles were found by its ribcage. Experts think Massospondylus may have swallowed these stones to help it digest its food. When food was swallowed, it was ground down by the stones. They worked like the blades of a food mixer to mash the leaves into a thick, mushy soup so that the dinosaur was able to absorb all the nutrients its large body needed.

To defend itself, Massospondylus had a huge thumb with a long, curved claw. Together with the second and third fingers, the thumb may also have been used for grasping things. The other two fingers were small and weak.

 

Apatosaurus June 28, 2011

Filed under: Sauropoda — muzillu @ 2:16 pm

Apatosaurus, also known by the popular but scientifically redundant synonym Brontosaurus, was a sturdy beast. It had a long, whiplash tail, which had about 80 bones in it.

Apatosaurus was a huge, quadrupedal sauropod, as long as a tennis court. It fed on leaves that it snipped from plants and trees with its weak, peg-like teeth. Its very long neck, which had 15 huge bones in it, was held up by strong muscles that ran along the neck bones.

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Name: Apatosaurus, meaning ‘deceptive reptile’

Size: 21-25m long and 5.8m high

Food: leaves and shoots of trees and shrubs

Lived: about 150 million years ago in the Late Jurassic Period in North America

Apatosaurus is a heavily built diplodocid. The vertebrae have a groove along the top. This held a strong ligament that supported the weight of the neck and the tail, like the cables on a suspension bridge. The ‘deceptive lizard’ of the name refers to the fact that the chevron bones attached to the vertebrae look confusingly like those of the aquatic reptile Mosasaurus. Although the head is about the size of that of a horse, the brain is only as big as that of a cat. The whole skeleton is similar to that of Diplodocus, but is much more stocky and massive, going for weight rather than length.

Apatosaurus had an extremely long tail, almost half of which was thin and whiplike. It probably used its tail to lash out at the hungry carnivores that preyed on the weakest members of the herd, such as the young and the very old dinosaurs. Recent computer modelling suggested that sauropods such as Apatosaurus were capable of producing a whiplike cracking sound of over 200 decibels with their tails, comparable to the volume of a cannon.

To support its great weight, Apatosaurus’ pillar-like legs ended in broad feet, rather like those of an elephant. Its front feet had a claw on the inside toe, which it used to kick out at attackers.

One of the most popular dinosaurs, Apatosaurus, keeps changing its identity. For almost a century it went by the evocative name Brontosaurus, the ‘thunder lizard’. In 1877 Othniel Charles Marsh discovered A. ajax and named it. Two years later he found a more complete animal which he named Brontosaurus excelsus. It was not until the twentieth century that it was realized that these were actually two species of the same genus. When there is confusion of this kind, with one animal given two names, it is the first name given that is deemed to be the valid one, in this case Apatosaurus. The official change took place in 1903. The length of time taken for Marsh’s misclassification to be brought to public notice meant that the latter name, associated as it was with one of the largest dinosaurs, became so famous that it persisted long after the name had officially been abandoned in scientific use.

 

Mamenchisaurus June 17, 2011

Filed under: Sauropoda — muzillu @ 3:58 pm

When it was discovered in 1952, the nature of the Mamenchisaurus constructus vertebrae was unclear. The vertebrae were so delicate and poorly preserved that they could not be excavated undamaged. Early restorations of this animal showed only a moderate length of neck. It was with the discovery of M. hochuanensis in 1957 that the fantastic length of the neck was appreciated.

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Name: Mamenchisaurus, meaning ‘lizard from Mamen Brook’

Size: 21-22m long and 5m high

Food: plants

Lived: 145 million years ago in China during the Late Jurassic Period

Mamenchisaurus has the longest neck of any known dinosaur. It consists of 19 vertebrae – the greatest number so far found – and is about 14m long, taking up about two-thirds of the length of the entire animal. The vertebrae are very thin and lightweight, made up of fine struts and sheets, rather like the later diplodocids. However, the short, deep skull shows that it belongs to the more primitive euhelopid group.

Mamenchisaurus’ long neck was supported by long, overlapping bones, which must have made the neck quite stiff and slow to turn. The neck also had strong muscles which supported its small, snake-like head. Mamenchisaurus was as long as a tennis court, but its body was slim. Its backbone was hollowed out in places, which made it very light for its size. The extreme length of its neck may have enabled Mamenchisaurus to reach in between closely-spaced trees to eat undergrowth in dense woodland.

145 million years ago, the area where this dinosaur lived was covered with vast, dense forests of redwood and sequoia trees. Herds of Mamenchisaurus lumbered along, using their small, peg-like teeth to nip off leaves and small shoots on the treetops that were out of the reach of other dinosaurs.

Mamenchisaurus walked on four legs, dragging its long, thin tail along the ground behind it. During the mating season, male Mamenchisaurus may have used their tails to lash each other in various fights for the females of the herd.

 

Barosaurus May 18, 2011

Filed under: Sauropoda — muzillu @ 11:49 am

Huge and long-necked, Barosaurus also had a lengthy tail which it wielded as a weapon against enemies. It lived in herds, which was also useful for defence against predators. Like all members of the sauropod group, it had one large, curved claw on the inner toe of its front foot.

This species is known from five partial skeletons from the Morrison Formation, three of them in Dinosaur Natural Monument in Utah, USA. The African species, until recently known as Gigantosaurus, was part of the Tendaguru fauna, and known from four skeletons. The rearing skeleton of Barosaurus in the American Museum of Natural History, at a height of 15m, is the tallest mounted skeleton in the world, only made possible by modern techniques of producing casts of fossil bones in lightweight materials.

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Name: Barosaurus, meaning ‘slow heavy reptile’

Size: up to 27m long

Food: plants and leaves

Lived: about 150-140 million years ago in the Jurassic Period in western North America

The bones in Barosaurus’ long neck were hollow and light, which meant it could lift its head to feed quite easily. If its neck bones had been solid, it would have been too heavy to lift. Barosaurus is very much like Diplodocus – indeed the limb bones are indistinguishable between the two genera – but its tail bones are shorter and its neck bones at least one-third longer, one of which is 1m long. The two genera were in fact about the same size overall. It was longer than Apatosaurus, but its skeleton was less robust.

The way that Barosaurus and the other diplodocids were balanced at the hips suggested that they could rear up on their hind legs for feeding or for scaring off predators.

Barosaurus was once thought to have held its head like a giraffe. In order to pump blood up to the brain – a height of around 12m, 10m above the heart – the heart would have had to have weighed about 1.5 tonnes. The larger a heart, the slower it beats. A 1.5 tonne heart would beat so slowly that the blood would run back down the neck before the next beat. In fact, the length of the neck has led some palaeontologists to suggest that there were several hearts along its length, to enable the blood to reach the brain when it was feeding from high trees.

However, a recent theory was postulated that, like a giraffe, it had arterial valves in its neck. These operate in response to differentials in fluid pressure, allowing the blood to be pumped up the neck but preventing most of it from falling back down. More recent computer modelling of diplodocids like Barosaurus has shown that they probably habitually held their necks more or less horizontally, thus restricting the problem to whether the animal reared up on its hind legs or not.

 

Brachiosaurus May 15, 2011

Filed under: Sauropoda — muzillu @ 10:19 pm

Brachiosaurus was one of the largest and heaviest dinosaurs that ever lived. The top of a man’s head would have reached only to this giant creature’s knees. It had a huge body, a very long neck, a small head and a long tail.

The best-known Brachiosaurus skeleton in the world is now thought to be a different genus – Giraffatitan. However, an even bigger animal, Ultrasauros, found in the Dry Mesa Quarry in Colorado, is now regarded as a particularly big specimen of Brachiosaurus. The original Brachiosaurus was discovered as two partial skeletons in the Morrison Formation near Fruita in Utah in 1900 by Elmer G. Riggs.

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Name: Brachiosaurus, meaning ‘tall-chested arm lizard’

Size: up to 23m long and 12m high

Food: leaves and shoots of trees

Lived: about 152-145 million years ago in the Late Jurassic Period in western North America

About half of the height of Brachiosaurus is due to the neck. This, with its long front legs and tall shoulders, meant that it could reach high up into the trees to feed. Even its front feet contributed to its high reach – the fingers are arranged long and pillar-like, and arranged vertically in the hand. Despite its fame, it is one of the rarest of the sauropods of the Morrison Formation.

A large, powerful heart pumped blood all the way up Brachiosaurus’ neck to its small brain. Some scientists believed it may have even have had several hearts to pump the blood around its massive body. Strong muscles along the neck bones helped to hold up its head. Unlike most dinosaurs, Brachiosaurus’ front legs were longer than its back legs. These helped to support the weight of its long neck.

Brachiosaurus browsed among the treetops that were out of reach for other herbivores. Using its long neck, it could pluck the highest leaves, in the same way that giraffes feed today. Brachiosaurus had strong jaws with teeth shaped rather like sharp-edged spoons for nipping off shoots and twigs. The position of the neck – whether it was vertical or horizontal – is an ongoing debate among scientists.

Brachiosaurus’ legs ended in short, thick toes. Underneath the bones of each foot was a pad which cushioned the legs against the jarring shock of its weight. Brachiosaurus held its legs straight underneath its body. This helped to support its enormous body weight. Elephants also hold their legs very straight beneath their bodies.

Brachiosaurus needed to eat an enormous amount to supply enough energy for its huge body to grow and move about. An elephant eats about 150kg of food a day. Brachiosaurus may have eaten as much as 1500kg of food a day – ten times as much as the average elephant. It probably travelled in herds and roamed over large areas of land each day to find fresh trees.

Because Brachiosaurus was so heavy, scientists once thought that it lived in lakes and rivers, where the water would support its massive weight. They believed that its legs would sink deep into the ground as it walked on land. Its nostrils were on the top of its head so it could probably keep its head above the water to breathe. In the water, Brachiosaurus would be safe from attack by fierce carnivores.

Nowadays however, scientists believe that Brachiosaurus lived only on land. The pressure of the water would have crushed its ribs, squashing its lungs. We now know, too, thats its legs were strong enough to carry the weight of its body as it lumbered through forests, along rivers and around lakes.


 

Dicraeosaurus May 12, 2011

Filed under: Sauropoda — muzillu @ 4:47 pm

The only late Jurassic diplodocid found in Africa was Dicraeosaurus. It was a member of the Tendaguru fauna and, along with the other animals, showed that the same families of dinosaurs existed in North America and Africa at that time. However, Dicraeosaurus was so different from the North American forms that it has been given its own family, the Dicraeosauridae.

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NameDicraeosaurus, meaning ‘two-forked lizard’

Size: Up to 6m tall and 20m long

Food: Plants

Lived: about 195 – 141 million years ago, in the Jurassic Period, in East Africa

For a diplodocid, Dicraeosaurus has a strangely short neck with only 12 vertebrae, far fewer than any of the other late Jurassic diplodocids except for Brachytrachelopan. The vertebrae have extremely long spines that are deeply cleft in the neck and form a kind of low sail over the back. These features would have made it look bigger in profile and would have helped to deter predators, or would have helped to regulate its body temperature. The tail has the typical diplodocid whiplash that would have been used as a weapon (although this is in dispute). It may also have been sufficiently fast to flee from its predators when threatened.

Dicraeosaurus lived in the Late Jurassic, alongside the likes of Giraffatitan and Kentrosaurus. However, it didn’t compete with them for vegetation. As there was a distinct difference in size between these dinosaurs, they would probably have browsed at different levels, allowing them to coexist without significant competition.

A huge discovery of dinosaur bones was made in 1907 in Tanzania, East Africa. It seems that many dinosaurs died near the mouth of a river and their bodies were washed on to mud banks. Some of the bones that were dug up belonged to dinosaurs that had not been discovered before. Among them was Dicraeosaurus, although it was not called this until 1935.

A full skeleton of Dicraeosaurus is mounted in the Humboldt Museum in Berlin, Germany, beside that of its Tendaguru neighbour Giraffatitan.