A Little History Of Science: Digging Up Dinosaurs
When I was very young, I had problems telling the difference between dinosaurs and dragons. In pictures, they often look alike, with huge teeth, powerful jaws, scaly skin and evil eyes, and they are sometimes shown attacking some other creature around them. Both kinds of creatures are clearly the sort that it is best to avoid.
There is a significant difference between dinosaurs and dragons, however. Dragons appear in Greek myths, legends about England’s King Arthur, Chinese New Year parades, and in many dramas throughout human history. But even if their power is such that they still feature in stories created today, they were always the products of the human imagination. Dragons never existed.
Dinosaurs, however, did once live. They were here for a very long time, even if human beings never saw them. They thrived around 200 million years ago, and we know about them because their bones have been preserved as fossils. The discovery of these bones in the early nineteenth century was an important step for science. First geologists, and then ordinary people, began to realise that the earth is far older than people had assumed.
The word ‘palaeontology’ was coined in France, in 1822, to give scientists a name for the study of fossils. Fossils are the outlines of parts of animals and plants that were once alive, but have slowly turned to stone (petrified) after they died, when the conditions are right. Fossils can be admired in many museums, and collecting them is fun. It is harder today, since a lot of the easy fossils have already been gathered for study and display. But in some places, like Lyme Regis on the south coast of England, the cliffs are still being eroded by the waves of the sea, and here fossils often come to light. People have been coming upon fossils for thousands of years.
Originally, the word ‘fossil’ just meant ‘anything dug up’, so ‘fossils’ might be old coins, pieces of pottery, or a nice quartz rock. But many of these objects buried in the earth looked like the shells, teeth or bones of animals, and gradually ‘fossil’ came to mean just these things that looked like bits of creatures. Shells of sea animals were sometimes found on mountain tops, far from the sea. Often the stony bones, teeth and shells didn’t seem to be like those of any known animal. In the 1600s, when naturalists began to puzzle about what had been found, they developed three sorts of explanation. First, some believed that these shapes had been produced by a special force within nature, striving, but failing, to create new kinds of organisms. They were similar to living plants and animals, but hadn’t quite made it. Secondly, others argued that fossils were really the remains of species of animals or plants that had simply not yet been discovered. So much of the earth itself remained unexplored, that these creatures would eventually be found in remote parts of the world, or in the oceans. A third group of scholars dared to suggest these organisms were creatures that had once been alive but were now extinct. If that was true, then the earth must be much older than most people thought.
It was not until the eighteenth century that the word ‘fossil’ got its modern meaning, that of the petrified remains of a plant or animal that had once been alive. The realisation of what this meant began to dominate scientific thinking. The scientist who convinced the world that some animals had become extinct was a Frenchman, Georges Cuvier (1769–1832). Cuvier was very good at anatomy, especially comparing the anatomy of different kinds of animals. He had a special interest in fish but also a vast knowledge of the whole animal kingdom. He dissected hundreds of different animals, then he compared the different parts of their bodies and explored what all their various organs did. He argued that animals are living machines in which every part has its proper purpose. He also noticed that everything in an animal’s body worked together. For instance, animals that eat meat have canines (sharp teeth), which permit them to tear the flesh of their prey. They have the correct digestive system, muscles, and all other characteristics they need to catch and live on meat. Those that graze on plants, like cows and sheep, have teeth with flattened ends, which help in grinding grass and hay. Their bone structure and muscles are for standing around rather than running and pouncing.
Cuvier’s belief that animals are so beautifully constructed that the whole fits together in harmony made it possible for him to say a lot about an animal’s structure and mode of life just by looking at one part of it. Find a canine tooth and you have found a carnivore, he said, and he would apply the same principles to fossils. With another anatomist he undertook a thorough investigation of the fossils found around Paris. They discovered that the fossils often resembled parts in living animals that could still be found in the area, but in many cases the teeth and bones had small, but significant, differences. By chance, the frozen remains of a large elephant were found in Siberia. Cuvier examined this ‘woolly mammoth’, as it was called, and argued that it was not only unlike any known living elephant, but that an animal of this size would surely have been noticed before, were it still roaming around somewhere. So it must have become extinct.
When they accepted the idea that some species of animals (and plants) were now extinct, it was much easier for naturalists to interpret the large numbers of fossils that were then being uncovered.
The discoveries of two rather unlikely people in England helped create the notion of a prehistoric world. The first of these was Mary
Anning (1799–1847). She was the daughter of a poor carpenter who lived in Lyme Regis, that place in southern England still being eroded by the sea. It was a brilliant place for Mary to hunt for fossils. Even as a young girl, she went fossil hunting, for good specimens could be sold to scientists and collectors. Mary and her brother Joseph used their local knowledge to develop a business collecting and selling fossils. In 1811 they found the skull, and then many of the other bones, of a strange creature. Estimated to have been seventeen feet long (five metres), it was unlike anything that had ever been found before. It was displayed in Oxford and was soon named Ichthyosaurus, which literally means ‘fish-lizard’, as it had had fins and so swam in water. Mary went on to find a number of other dramatic fossils, including one that had some resemblance to a giant turtle, but without any evidence that it had ever had a shell. This one was named Plesiosaurus, meaning ‘nearly a reptile’.
These discoveries brought her fame and some money. But as fossil hunting caught on, she found the competition fierce and had trouble supporting herself and her family through her business.
Mary Anning had little education and lost control over her fossil finds once she had sold them. Gideon Mantell (1790–1852) faced problems of a different kind. He was a family doctor in Lewes, Sussex – also in southern England – and had access to many fossils in limestone quarries nearby. As a doctor he had a good knowledge of anatomy and was able to interpret the fossils. But he had to fit his fossil work around a busy medical practice and a growing family. He turned his house into a kind of fossil museum, which didn’t please his wife. Travelling to London to present his findings to the scientists there was a slow and expensive business.
Despite these problems, Mantell persisted, and was rewarded by uncovering several exotic beasts. In the 1820s, he found some teeth of a kind not seen before, and the original owner of the teeth was named Iguanodon, meaning ‘having a tooth like an iguana’ (a kind of tropical lizard). Some admirers gave him a more complete skeleton of the iguanodon that they had found. Mantell also discovered an armoured dinosaur, Hylaeosaurus, which confirmed that some of these gigantic creatures walked on land. Others were unearthed that had features of birds, so this strange world had creatures that lived in the sea, on the land and in the air.
When we see these enormous, wonderful creatures reconstructed in museums, it is difficult to understand how hard it was for the men and women who first uncovered them. The fossilised bones were often scattered and the skeletons had bits missing. They had only a limited number of living or fossilised animals to compare the findings with, and they had none of the modern techniques of dating their discoveries. They could only estimate the size of their finds by comparing the bones they had discovered – a thigh bone, for example – with large living animals, such as elephants or rhinoceroses. The estimated sizes were staggering. They used Cuvier’s principle to help reconstruct whole skeletons from the parts and speculate on what the animal might have eaten, how it moved, and whether it lived on land, in the water, in the air, or some combination. A lot of their ideas had to be revised as more dinosaurs were discovered and more was learned about the early history of life on earth. But their findings changed forever how we think about the world we inhabit.
‘Dinosaur hunters’ made the general public realise how old the earth was, and how there had been complex creatures living long before human beings appeared. This ancient world captured their imagination, and fanciful pictures appeared in many popular magazines. Writers like Charles Dickens could refer to these giant reptiles, knowing that their readers would understand what they were talking about. The name ‘dinosaur’ was first used in 1842: it roughly means ‘fearfully great lizard’. New kinds of dinosaurs continued to be uncovered, not only in England but elsewhere.
They were quickly integrated into a general history of life on earth, and their period on earth was roughly calculated from the ages of the rocks in which they were found. Richard Owen (1804–92), the man who gave them the name ‘dinosaurs’, used his own work on these creatures to further his scientific career. He was behind the building of what today is the Natural History Museum in London. It is a wonderful museum, and the dinosaurs still have a prominent place in it. Many of those on display are original specimens found by people like Mary Anning.
In 1851, London hosted the first in a series of World’s Fairs. Called the Great Exhibition, it brought together displays of science, technology, art, transport and culture from all over the world. The Exhibition was housed in a building of amazing daring: the ‘Crystal Palace’, a gigantic glass house, located in the centre of Hyde Park, right in the heart of London. It was 33 metres tall, 124 metres wide and 563 metres long. People thought you couldn’t build anything so large of glass and steel, but Joseph Paxton did. He was a gardener and builder who had experience constructing large greenhouses for Victorian gentlemen. The Exhibition was like nothing that had ever happened before, and six million people from all over the world flocked to see it during the six months it lasted.
When it closed, the Crystal Palace was taken down and moved to Sydenham Park on the southern edge of London. As part of the development of that site, the world’s first theme park was created. It was devoted to dinosaurs and other creatures of the prehistoric world. Gigantic replicas of the Iguanodon, Ichthyosaurus, Megalosaurus and other beasts were constructed and placed in and around a man-made lake. The Iguanodon was so large that on New Year’s Eve, 1853, twenty-four guests had dinner in the mould used to make its huge body. The area is still called Crystal Palace today, although the glass building burned down in a terrible fire in 1936.
Some of the reconstructed dinosaurs don’t look quite right now, but they survived the fire and can be seen today, battered and worn, but still magnificent reminders of the past. We now know much more about the Age of Dinosaurs. Many different kinds have been found and we can date their ages more precisely than Mantell or Owen could. We sometimes say that they disappeared rather quickly. (Geological time is very slow, as we shall see in the next chapter.) What we mean to say is that the large dinosaurs went extinct, probably as a result of changes in the climate, after an enormous asteroid struck the earth about sixty- five million years ago. But not all of them disappeared. Some of the smaller dinosaurs survived and evolved, and you can see their descendants in your garden everyday. They are called birds.