It's all rather confusing.
Life is resilient, but any particular species may not be. Life is constantly devising new tricks. The one with eggs is brilliant: provide the developing embryo with its own personal life-support machine. Inside, the environment is tailored to the needs of that species, and what's outside doesn't matter much, because there's a barrier to keep it out.
Life is adaptable. It changes the rules of its own game. As soon as eggs make their appearance, the stage is set for the evolution of egg-eaters ...
Life is diverse. The more players there are, the more ways there are to make a living by taking in each others' washing.
Life is repetitious. When it finds a trick that works, it churns out thousands of variations on the same basic theme. The great biologist John (J.B.S.) Haldane was once asked what question he would like to pose to God, and replied that he'd like to know why He has such an inordinate fondness for beetles[46].
There are a third of a million beetle species today, far more than in any other plant or animal group. In 1998 Brian Farrell came up with a possible answer to Haldane's query. Beetles appeared about 250 million years ago, but the number of species didn't explode until about 100 million years ago. That happens to be just when flowering plants came into existence. The 'phase space' available for organisms suddenly acquired a new dimension, a new resource became available for exploitation. The beetles were beautifully poised to take advantage by eating the new plants, especially their leaves. It used to be thought that flowering plants and pollinating insects drove each other to wilder and wilder diversity, but that's not true. However, it is true for beetles. Nearly half of today's beetle species are leaf-eaters. It's still an effective tactic.
Sometimes natural disasters don't just eliminate a species or two. The fossil record contains a number of 'mass extinctions' in which a substantial proportion of all life on Earth disappeared. The best-known mass extinction is the death of the dinosaurs, 65 million years ago.
In order not to mislead you, we should point out at once that there is no scientific evidence for the existence of any dinosaur civilization, no matter what events are going on in the Roundworld Project. But... whenever a scientist says 'there is no scientific evidence for', there are three important questions you should ask -especially if it's a government scientist. These are: 'Is there any evidence against?, 'Has anyone looked?', and 'If they did, would they expect to find anything?'[47]
The answers here are 'no,' 'no', and 'no'. Deep Time hides a lot, especially when it's assisted by continental movement, the bulldozing ice sheets, volcanic action and the occasional doomed asteroid. There are few surviving human artefacts more than ten thousand years old, and if we died out today, the only evidence of our civilization that might survive for a million years would be a few dead probes in deep space and various bits of debris on the Moon. Sixty-five million? Not a chance. So although a dinosaurian civilization is pure fantasy, or, rather, pure speculation, we can't rule it out absolutely. As for dinosaurs who were sufficiently advanced to use tools, herd other dinosaurs ... well, Deep Time would wash over them without a ripple.
Dinosaurs are always among the most popular exhibits at museums. They remind us that the world wasn't always like it is now; and they remind us that humans have been on this planet for a very short time, geologically speaking. Basically, dinosaurs are ancient lizards. The ones whose bones we all go to gawp at in museums are rather big lizards, but many were much smaller. The name means 'terrible lizard', and anyone who watched Jurassic Park will understand why.
An Italian fossil collector who watched the Spielberg movie suddenly realized that a perplexing fossil, filed away for years in his basement, might well be a bit of a dinosaur. He then sent it to a nearby university, where it was found not just to be a dinosaur, but a new species. It was a young therapod, small flesh-eating dinosaurs that are the closest relatives of birds. Interestingly, it didn't have any feathers. A story straight out of the movies: narrative imperative at work in our own world ... traceable, as always, to selective reporting. How many fossil hunters owned a bit of dinosaur bone but didn't make the connection after seeing the movie?
In the human mind, dinosaurs resonate with myths about dragons, common to many cultures and many times; and many miles of suggestions have appeared to explain how the dragon-thoughts in our minds have come down to us, over millions of years of evolution, from real dinosaur images and fears in the minds of our ancient ancestors. However, those ancestors must have been very ancient, for those of our ancestors that overlapped the dinosaurs were probably tiny shrewlike creatures that lived in holes and ate insects. After more than a hundred million years of success, the dinosaurs all died out, 65 million years ago, and the evidence is that their demise was sudden. Did proto-shrews have nightmares about dinosaurs, all that time ago? Could such nightmares have survived 65 million years of natural selection? In particular, do shrews today have nightmares about fire-breathing dragons, or is it just us? It seems likely that the dragon myth comes from other, less literal, tendencies of that dark, history-laden organ that we call the human mind.
Dinosaurs exert a timeless fascination, especially for children. Dinosaurs are genuine monsters, they actually existed, and some of them, the ones we all know about, were gigantic. They are also safely dead.
Many small children, even if they are resistant to the standard reading materials in school, can reel off a long list of dinosaur names. 'Velociraptor' was not notable among them before Jurassic Park, but it is now. Those of us who still have an affection for the brontosaur often need to be reminded that for silly reasons science has deemed that henceforth that sinuous swamp-dwelling giant must be renamed the apatosaur[48]. So attuned are we to the dinosaurs that the drama of their sudden disappearance has captured our imaginations more than any other bit of pakeontology. Even our own origins attract less media attention.
What about the sudden demise?
For a start, quite a few scientists have disputed that it ever was sudden. The fossil record implicates the end of the Cretaceous period, 65 million years ago, as 'D-Day'. This was also the start of the so-called Tertiary period, or Age of Mammals, so the end of the dinosaurs is usually called the K/T boundary, 'K' because Germans spell Cretaceous with a K. But if we assume that the end of the Cretaceous was 'when it happened', then many species seemed to have anticipated their end by vanishing from the fossil record five to ten million years earlier. Did amorous dinosaurs, perhaps, say to each other 'It's just not worth going through with this reproduction business, dear, we're all going to be wiped out in ten million years.'? No. So why the fuzzy fade-out over millions of years? There are good statistical reasons why we might not be able to locate fossils right up to the end, even if the species concerned were still alive.
To set the remark in context: how many specimens of Tyrannosaurus rex, the most famous dinosaur of all, do you think that the world's universities and museums have between them? Not copies, but originals, dug from the rock by palaeontologists? Hundreds ... surely?
No. Until Jurassic Park, there were precisely three, and the times when those particular animals lived have a spread of five million years. Three more fossilized T. rexes have been found since, because Jurassic Park gave dinosaurs a lot of favourable publicity, making it possible to drum up enough money to go out and find some more. With that rate of success, the chance of a future race finding any fossil humanoids, over the whole period of our and our ancestors' existence, would be negligible. So if some species had survived on Earth for a five million year period, it is entirely likely that no fossils of it will have been found, especially if it lived on dry land, where fossils seldom form. This may suggest that the fossil record isn't much use, but quite the contrary applies. Every fossil that we find is proof positive that the corresponding species did actually exist; moreover, we can get a pretty accurate impression of the grand flow of Life from an incomplete sample. One lizard fossil is enough to establish the presence of lizards, even if we've found only one species out of the ten thousand that were around.
46
Readers of the Discworld book The Last Continent will recall that, by an amazing coincidence, beetles were something of a passion for the God of Evolution.
47
Rincewind would add some more:
'Is it safe?'
'Are you sure?'
'Are you absolutely sure?'
48
A worse case is what used to be called Eohippus, the Dawn Horse - a beautiful, poetic name for the animal that formed the main stem of the horse's family tree. It is now called Hyracotherium, because somewhat earlier somebody had given that name to a creature that they thought was a relative of the hyrax, represented by a single fossil shoulder-blade. Then it turned out that the bone was actually part of an Eohippus. Unfortunately, whoever officially names a species first must get priority, so now the Dawn Horse has a silly, unpoetic name that commemorates a mistake.
We lost 'Brontosaurus' - thunder-lizard - for a similar reason. Thunder Lizard ... what a marvellous name. 'Apatosaurus'? It probably means 'Gravitationally challenged Lizard'.
The moral of this tale is that when learned committees of elderly scientists meet to discuss an exceptional issue they can always be trusted to make a completely ridiculous decision. Quite unlike the wizards of Unseen University, naturally.