The Science of Discworld Revised Edition

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.
    4 Lots of ammonite species died out 5–10 million years before the K/T boundary, so it looks as if their extinction genuinely was gradual. But whatever it was that happened at the K/T boundary finished them off.

THIRTY-NINE
BACKSLIDERS

    GLOOM HAD SETTLED over the wizards. Some of them had even refused a third helping at dinner.
    ‘It’s not as if they were
very
advanced,’ said the Dean, in an attempt to cheer everyone up. ‘They weren’t even using metal. And their writing was frankly nothing but pictograms.’
    ‘Why doesn’t that sort of this thing happen here?’ said the Senior Wrangler, merely toying with his trifle.
    ‘Well, there have been historical examples of mass extinction,’ said Ponder.
    ‘Yes, but only as a result of argumentative wizardry. That’s quite different. You don’t expect rocks to drop out of the sky.’
    ‘You don’t expect them to stay
up
,’ said Ridcully. ‘In a
proper
universe, the turtle snaps up most of them and the elephants get the rest. Protects the world. Y’know, it seems to me that the most sensible thing any intelligent lifeform could do on that little world would be to get off it.’
    ‘Nowhere to go,’ said Ponder.
    ‘Nonsense! There’s a big moon. And there’s other balls floating around this star.’
    ‘All too hot, too cold, or completely without atmosphere,’ said Ponder.
    ‘People would just have to make their own entertainment. Anyway … there’s plenty of other suns, isn’t there?’
    ‘All far too far away. It would take … well, lifetimes to get there.’
    ‘Yes, but being extinct takes forever.’
    Ponder sighed. ‘You’d set out not even knowing if there’s a world you could live on, sir,’ he said.
    ‘Yes, but you’d be leavin’ one that you’d know you couldn’t,’ said Ridcully calmly. ‘Not for any length of time, anyway.’
    ‘There are new lifeforms turning up, sir. I went and checked before dinner.’
    ‘Tell that to the lizards,’ sighed the Senior Wrangler.
    ‘Any of the new ones any good?’ said Ridcully.
    ‘They’re … more fluffy, sir.’
    ‘Doin’ anything interesting?’
    ‘Eating leaves, mainly,’ said Ponder. ‘There are some much more realistic trees now.’
    ‘Billions of years of history and we’ve got a better tree,’ sighed the Senior Wrangler.
    ‘No, no, that’s got to be a step in the right direction,’ said Ridcully, thoughtfully.
    ‘Oh? How so?’
    ‘You can make paper out of trees.’
    The wizards stared into the omniscope.
    ‘Oh, how nice,’ said the Lecturer in Recent Runes. ‘Ice
again
. It’s a long time since we’ve had a really big freeze.’
    ‘Well, look at the universe,’ said the Dean. ‘It’s mainly freezing cold with small patches of boiling hot. The planet’s only doing what it knows.’
    ‘You know, we’re certainly learning a lot from this project,’ said Ridcully. ‘But it’s mainly that we should be grateful we’re living on a
proper
world.’
    A few million years passed, as they do.
    The Dean was on the beach and almost in tears. The other wizards appeared nearby and wandered over to see what the fuss was about.
    Rincewind was waist deep in water, apparently struggling with a medium-sized dog.
    ‘That’s right,’ the Dean shouted. ‘Turn it round! Use a stick if you have to!’
    ‘What the thunder is going on here?’ said Ricully.
    ‘Look at them!’ said the Dean, beside himself with rage. ‘Backsliders! Caught them trying to return to the ocean!’
    Ridcully glanced at one of the creatures, which was lying in the shallows and chewing on a crab.
    ‘Didn’t catch them soon enough, did you,’ he said. ‘They’ve got webbed paws.’
    ‘There’s been too much of