Where Dinosaurs Lived

 

 


Most of the knowledge we have about where and how dinosaurs lived comes from the bones that scientists have found. Most dinosaur bones have been found at the sites of ancient river-beds. Flash floods may have caused many dinosaurs to die all at the same time in these spots. Disasters like these could have left behind the huge dinosaur graveyards full of bones that scientists have found in some areas.

But scientists cannot be completely certain about where some dinosaurs lived. Bones might have been carried down the river from their original sites. Drought might have caused some herds to migrate from their usual homes to the river sites in search of food and water. As regions dried up, many species may have died together in areas where they did not usually live. With some species, scientists have only found the remains of one or two individual dinosaurs. It is often difficult for scientists to decide how much information about the whole species these few fossils tell us.

What scientists can usually tell from fossils is the species of dinosaur they are from and roughly where that species lived. The map above shows where a number of different dinosaurs' fossils have been found so far. These dinosaurs might have also lived in other parts of the world where their bones have not yet been found. Remember that the continents of the world have moved since some of these creatures lived. The countries and climates they are found in have changed greatly since the times in which they lived.


 

AUSTRALIAN DINOSAURS


Many kinds of dinosaurs have lived in Australia. They were the main animals for more than 100 million years. The earliest known Australian dinosaurs lived about 170 million years ago. Dinosaurs were in other parts of the world millions of years earlier than in Australia. Many of those dinosaurs have not been found in Australia.

The name 'dinosaur' means 'terrible lizard', but some were only the size of chickens! Others were of enormous size. The dinosaur fossils we have are mostly those of animals that were caught in mud or fell into flooded streams. Most animals simply died or were killed and eaten, leaving nothing behind them. Perhaps there were species of dinosaurs that left no fossils, so we do not know that they existed.

The search for fossils is still going on. In 1992 new species of dinosaur have been recognised from only one or two bones. Very little may still be known about the animals. Some dinosaurs have left no traces except footprints in mud that hardened into rock.

WHAT FOSSILS TELL US

We can learn a lot about dinosaurs from their fossils. Footprints made by dinosaurs are sometimes found in rocks. These are called trace fossils. From looking at trace fossils, experts worked out that about 130 small Coelurosaur dinosaurs were grazing or drinking at a lake near Winton in Queensland. A large flesh-eating carnosaur (carnivorous dinosaur) came along. The little dinosaurs ran away and were chased by the carnosaur. Tracks in the hardened mud show how fast they ran and in which directions. None seem to have been caught, as no drag-marks were left. Scientists can tell all this information from tracks, even though none of the 'small dinosaur' remains have been found in Australia.

AUSTRALIA'S OWN DINOSAUR

Muttaburrasaurus probably lived only in Australia. An almost complete fossil was found in 1963 at Muttaburra which is about 100 kilometres from Longreach in Queensland. This dinosaur was about 7 metres long. It was a land animal with feet shaped like birds' feet. There was a long, sharp spike on each 'thumb'.

At the front of its jaw it had a heard beak, this was used to tear vegetation for eating. Along its jaws, set in towards the midline, were many teeth suggesting it also had large fleshy cheeks. Muttaburrasaurus was a herbivore. There was a strange, bony protusion on its snout which may have assisted its sense of smell or amplified its call.

THE KILLER THAT ATE DINOSAURS

Allosaurus killed and ate other dinosaurs, even the huge plant-eating dinosaurs. It was the largest flesh-eating dinosaur in Australia at that time. An adult Allosaurus was about 10 metres long and 4 metres high, but its brain was only as big as that of a cat.

The ankle-bone of an Allosaurus was found with the bones of small plant-eating dinosaurs near Cape Patterson in Victoria.

The bones found near the Victorian coast were about 125 million years old. In other countries these dinosaurs became extinct about 260 million years ago. This means that the Victorian species is the latest surviving Allosaurus known. Allosaurus fossils have been found on most continents and would have become wide spread when the continents were all joined in one large land mass.

THE MEAT-EATERS

The therapods were a group of meat-eating dinosaurs &endash; carnosaurs. They must have been wide-spread in Australia because remains of these animals have been found in at least three States. Therapods ran quickly on their hind legs, grabbing their prey with the claws on their front feet.

Allosaurus was one of the larger kinds of therapods. A smaller therapod was discovered at Dinosaur Cove on the coast of western Victoria. A raptor bone was found at Lightning Ridge in western New South Wales. This dinosaur was about the size of a small adult Allosaurus. Kakuru kujani was much smaller, being only the size of a heron. A bone from one these therapods was found at Andamooka in South Australia.

LONG-NECKED GIANTS

Saurpods were large long-necked dinosaurs which first appeared during the early Jurassic. The Rhoetosaurus is one of the oldest known Sauropods in the world. Sauropods were much more widespread in the Upper Jurassic and Cretaceous. They ate ferns, cycads and conifers that were related to pine trees. Grasses had not yet evolved.

Sauropods had to eat enormous quantities of food. To aid in the breakdown of the food they ingested stones which remained in their stomach. These helped to mechanically breakdown leaves, stems, stalks etc. Some sauropods have been found with these stomach stones (gastroliths) in amongst the bones of their remains. They are smooth and round as they were worn in the stomach during digestion. Sauropods probably had several large stomachs to help digest the food.

Austrosaurus was a sauropod about 17 metres long. Some of its bones were found in central Queensland. Bones from another big sauropod, about 26 metres long, were found near Hughenden in Queensland. Only a few fossils of sauropods have been found in Australia, so it does not give us any idea of how many sauropods lived in Australia during the Jurassic and Cretaceous. Some remains of sauropods have also been found in New Zealand.

SOME DINOSAURS WERE SMALL

As well as the giant animals Australia also had several species of small dinosaurs. They could run quickly on two legs to escape from their enemies.

The hysilophodonts in Australia were the first described from part of a thigh bone, but several other thigh bones were found at Dinosaur Cove and other places along the western Victorian coast, as well as in the Strzelecki Ranges in south Gippsland. These animals might have been much more common in south-east Australia than in any other parts of the world.

At least three, and perhaps five, species of hypsilophodonts have been found. Some were the size of chickens while others were about as tall as a small, human adult. What we now call Victoria was located much further south than at present and so there must have been long periods of darkness during winter. These dinosaurs evolved large eyes probably to enable them to see better during the dark winter months. They were herbivorous.

AN ARMOURED DINOSAUR

Some dinosaurs were covered by huge bony scales which acted like a suit of tough armour. The armour protected the dinosaur from its enemies. Ankylosaurs were one type of armoured dinosaur and nodosaurus are a closely related family. They probably moved along slowly on all four feet. They could not run very fast and could not fight. Their armour was their only protection against predators such as Allosaurus. They were very low, broad animals with massive limbs. The smallest ankylosaur was probably the length of a man, while the largest was the length of a bus and weighed as much as a small elephant.

The fossils of armoured ankylosaurs have been found in North America, Europe and Asia as well as in Australia. These dinosaurs seem to have appeared first during the Jurassic, but there were many more of them during the Cretaceous. Minmi paravertebrata is a small nodosaurid, about 2 metres long, from the early Cretaceous (about 100 million years ago) from near Roma, Queensland. So far it is the only unquestionable ankylosaurid from Gondwana.

A KILLER IN THE SEA

Kronosaurus queenslandicus was one of the fiercest animals that ever lived in the sea. It was a pliosaur about 14 metres long, and had four big flippers for swimming. Its head was about 3.5 metres long which was a quarter of the animal's length. Its pointed teeth were about 25 centimetre long and could grab fish, turtles or anything else that came along, including the other big reptiles that were in the sea at that time.

Fossils of Kronosaurus have been found in the Hughenden district of Queensland. This area was covered by shallow seas about 120 million years ago.

There may have been two or three species of Kronosaurusin Australia, but more study of the bones is still needed.

TOWARDS THE AUSTRALIA OF TODAY

The dinosaurs became extinct after being in Australia for about 150 million years. This major extinction took place 65 million years ago. Their places were taken by marsupials such as kangaroos, wombats and other animals with pouches. Some marsupials became larger than bullocks. Others hunted like lions or wolves. One large animal had a trunk. There were giant birds, too. One species was much bigger than an ostrich or emu. In time, these large marsupials died out or became smaller, and were replaced by modern animals.

The animals were affected by the invasion of the continent by humans, by changes in the climate, which led to the replacement of forests with the eucalypts and grass lands we know. Mountains in eastern Australia became higher, partly because of the action of volcanoes. There were rises and falls in sea-levels, too.

The coming of people to Australia brought big changes. The Aborigines helped to change the vegetation, and they hunted the animals for food. The Europeans who settled in Australia in 1788 farmed the land and brought new plants and animals. Some of those animals and plants have done great damage to Australia.

 

Australian Dinosaur Links

Australian Dinosaurs

Dinosaurs of Ancient Queensland

Polar Dinosaurs in Australia

Australian Dinosaur Sites


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