Dinosaurs
The old dinosaur had been struggling for breath all morning. Eventually it lay down on the side of the riverbank and died. Other smaller dinosaurs approached the lifeless body, and sensing it was dead began pulling at its scales and biting into its flesh. Soon they were through the skin and feeding on the flesh. The smell of the blood brought other larger dinosaurs to the scene. They chased off the smaller ones and began to pull on the rib bones so they could probe deeper into the dinosaur for their meal. Over a few days the remains of the old dinosaur had many visitors and each one went away with a full stomach. Soon only flies were found feeding on the bones.

In the many years that followed the bones became covered by the sand on the riverbank. In time, long after the dinosaurs had died out, this sand became squashed into rocks and the bones turned into fossils. Millions of years passed and the sandstone came to form part of the desert. The heat of the Sun caused the rock to expand or swell a little. The cool of the nights caused the rock to shrink back. These changes broke up the rock into lumps. Winds picked up sand and pounded the grains into the rock surface. The grains chipped away the rock and slowly it became worn down. Eventually part of a fossil bone from the old dinosaur was exposed. Over time more of the rock wore away and the bone fell out onto the desert sand. It was only a small bone and when an unusually heavy shower of rain occurred, it was washed further away down the hillside.

In time the fossil bone rolled to the side of a road. One day a jeep pulled up close by. Three dinosaur hunters got out and looked over the land. They knew that the sandstone was the right age to have dinosaur fossils in it but they did not know where to look. One of the hunters began walking along the road to see if she could find a better view. As she walked she looked at the rocks on the roadside. She had not walked far when she saw the dark fossil bone of the old dinosaur standing out among the brown desert rocks. She called the other dinosaur hunters over and they agreed she had found a dinosaur bone.

All three dinosaur hunters looked up the hill. They could see places where the water had washed down the rock and they climbed up to investigate. By now another dinosaur bone had appeared at the surface. It was larger than the other and stuck out from the side of the rock. It was not long before the dinosaur hunters found it and decided to set up a camp.

The three dinosaur hunters telephoned other dinosaur hunters to tell them about their find and soon the camp was full of men and women with picks and shovels. The dinosaur hunters did not just attack the hillside to try and find more bones. They carefully removed the bone that was sticking out from the rock then broke up more rocks around it. As they worked they discovered more bones. When a bone was discovered, work stopped to examine it. Sometimes the bones were photographed as they lay in the rocks.

After many weeks of work the dinosaur hunters had found most of the bones of the old dinosaur. They had been scattered about by the animals that fed on the dead body so many millions of years ago. The ancient river had washed away some of the bones so that they would never be found but the dinosaur hunters were happy with what they had found. When all the studies at the camp were complete, the dinosaur bones were carefully packed into boxes and taken to a distant museum. Here more scientists studied the bones and put them together. They were pleased that they had enough bones to make a skeleton and eventually mounted the bones on wires and displayed the dinosaur skeleton in the museum. Over sixty million years since the dinosaur lay down its head on the riverbank its skull was now sitting on top of its spine and looking out over very different surroundings.

When did dinosaurs live on the Earth?
From between 240 million years ago and 65 million years ago. There were dinosaurs walking on the Earth for 175 million years of the Earth's history.

Were there people around at the time of the dinosaurs?
No. People belong to the mammal group of animals. At the time the mammals were small mouse-like creatures. Only after the dinosaurs had died out did the mammals start to develop into other forms such as cats, dogs and apes. Many scientists believe that humans developed from ape-like animals just a few million years ago. We can only find fossils of humans like ourselves that are about a quarter of a million years old. This suggests that there have only been humans like us on the planet for a short time compared to the time that dinosaurs lived on the Earth.

How do we know so much about dinosaurs if nobody has seen one?
We can build up our ideas about dinosaurs from the fossils that we find and we can look at how reptiles live today. For example, if all the bones of a dinosaur are found its skeleton can be rebuilt. By looking at the shapes of the bones scientists can work out the size of the muscles connected to them. The skeleton and the muscles give the dinosaur its body shape so an artist can then draw the shape of the dinosaur. Some fossil dinosaur scales have been found so this suggests that dinosaurs had a scaly skin like reptiles today. An artist can then look at the scales of reptiles living today to help draw in how the scales on a dinosaur may have looked.

How does a fossil bone form?
When a dinosaur dies its soft parts either rot away or are eaten by scavengers. The bones and teeth are very hard but can, in time, be rotted away by microbes as they feed. If the bones are coated in mud or sand, microbes cannot feed so the bones do not rot. Water passing through the mud and sand carries minerals, which settle down in the cavities in the bones and eventually replace the original bony material. The fossil bone has the same shape as the original bone but is not made from the same material.

Did dinosaurs leave other fossils behind besides bones?
Yes, they did. In addition to some scales they left teeth, claws, eggs, footprints and even droppings. All these fossils have been used to help work out how dinosaurs looked and how they lived.

Were there many different kinds of dinosaur?
Yes, and we are still discovering the fossils of new dinosaurs today. The well known kinds are Tyrannosaurus with its huge mouth packed full of long sharp teeth, Triceratops with the three long horns sticking out from its head, Diplodocus with its long neck, huge body and long tail and Stegosaurus with its back covered in broad, pointed plates. There were many other kinds. Some had a hollow crest on their head which scientists think they used as a trumpet. Some dinosaurs had skulls shaped liked crash helmets. Scientists believe that they used to head butt each other like sheep and goats do today. One dinosaur, called Ultrasaurus, was so large that it weighed more than eight elephants.

Why are there no dinosaurs alive today?
Dinosaurs became extinct 65 million years ago. It has been discovered by other studies on rocks that the Earth was hit by a very large meteorite at this time. The dust sent up into the atmosphere then could have joined with dust from erupting volcanoes to form a huge dark cloud that kept out most of the sunlight. This caused many plants to die. As large dinosaurs need large amounts of plant food they died out too. The meat-eating dinosaurs were left without any plant-eating dinosaurs to prey on so they also died out.

Why did the other animals survive?
They could find enough food to eat until the clouds cleared and large numbers of plants began to grow again. Some small dinosaur skeletons have been found with marks around them that look as if they were made by feathers. These dinosaurs also had skeletons which were a little like bird skeletons. Some scientists believe that some of these dinosaurs did not become extinct but changed into birds. If they are right, when you put food on a bird table you are setting out a meal for small, feathered dinosaurs.