Sixty-five million years ago, there were many huge lizards. Most of them were really happy being lizards, and would spend all of the time they could doing lizardy things. Some wanted to be the biggest lizards, and grew so large and so heavy that it would sound like peals of thunder if you could hear them walking about on their lizardy way. Others wanted to be the most terrible lizards, and they developed big scary teeth and sharp, shiny talons. The most terrible lizards were feared by many of the other lizards, but it was a fear that sprang from awe: they were all happy that each was, in their own way, the most lizardy of the lizards. And they were all happy that each of the other lizards they met was trying to be, in their own way, the most lizardy of lizards.
For the lizards met often. They would have their big get-togethers where the big lizards and the small lizards and the terrible lizards and the scaly lizards would each talk about how they handle being so big, or so small, or so terrible, or so scaly. And the other lizards would listen to these talks, and they would applaud the speakers for being so big, or so small, or so terrible, or so scaly. Having seen these examples of lizardly apotheosis, they would try to emulate them. So it was that the lizard world became bigger, but also smaller, and more terrible, and more scaly.
But it seems that not all of the lizards shared these goals of ever-increasing lizardhood. Some would try different things. A group of lizards found that they could regulate their own blood temperature, they would no longer need to sit in the sun all morning like the other lizards. One group of lizards turned their feathery covering to the task of improved aerodynamics. Another group turned it to a sort of coat, which stopped them getting so cold.
The big meetings of lizardy lizards did not really pay these developments much notice, as they were not very lizard like changes. They knew that they were lizards! They should do the lizardy things, like getting bigger or smaller or more terrible or more scaly! They put over eighty hours a week into it, they were passionate about it. The world was, for them, all about being more lizardly every day.
Some of the things that the decidedly non-lizardlike groups were coming up with did take a sort of root among those who called themselves the “lizard community”, but only to the extent that they could be seen as lizardy things. So ideas from the feather aerodynamics group became diluted, and were called “flight-oriented lizarding”. At the big gatherings of all the lizards, the FOL evangelists would show how they had made things that looked a bit like the feathers used for aerodynamics, but which were more lizardy. They had some benefit to lizards in that they slowed them down slightly as they fell out of trees. And, of course, as this was something that you had to be able to demonstrate expert lizardly competence in, they invented the idea of the master flight-oriented lizard.
All sorts of rules were invented to demonstrate competency and master-lizardliness in the flight-oriented world. This feather and that feather must each have a single responsibility: this for slowing the fall, that for turning. Feathers must be open for falling but closed for impact. Specific types of feathers could be invented, but only where they could be used in place of the more generic feathers. Feathers had to be designed so that they never got into the area around a lizard’s eyes (the in-the-face segregation principle). Despite the fact that flight-oriented lizards only used their feathers for falling out of trees, feathers had to be designed to work when travelling upwards too (the descendency inversion principle).
But to the expert lizards—the biggest, smallest, scaliest and most terrible lizards—something felt uncomfortable. It felt like people were saying that there was something else to do than being an expert lizard, as if lizardness wasn’t enough. So, of course, they arranged another meeting of all the lizards. Expert lizards and novice lizards and improving lizards all came together, that one day sixty-five million years ago, and they met in the town of Chicxulub. And the most expert of the expert lizards got up in front of all the lizards, and said this:
If you want to carry on at lizarding you have to really love it. You’ve got to want to put every waking moment into becoming a better lizard. You’ve got to look up after practising your lizarding, and be shocked at how much time has gone past. If that isn’t you, if you don’t absolutely love everything about lizarding, perhaps it’s time to move on and do something else.
Many of the expert lizards agreed with this idea, and were pleased with themselves. But many that had been trying other things, the fur or the flying or the warm blood, were confused: did they want to be lizards forever, and strive toward the best of lizardliness, or not? Did they perhaps want to explore the opportunities presented by warm blood, or flying, or fur?
And so it was that at Chicxulub, as a rock from outer space danced through the upper atmosphere, pushing and heating and ionising the air in front of it, people chose between the many paths open to them.