Asteroids happen, and being big won’t save you. In our current world of apocalyptic economic threats, that’s a lesson that seems worth re-learning. The latest version comes in a fascinating study of the fate of the dinosaurs from the University of Zurich and the Zoological Society of London. The paper’s abstract explains that the study offers a mechanism for “how mammals and birds, but not dinosaurs, were able to persist beyond the K–T boundary”, which is the infamous geological layer associated with the end of the dinosaurs and the beginning of the rise of our mammalian ancestors.
It all comes down to eggs. Unlike mammals, even the biggest dinosaurs raised their young from eggs. But eggs can only get so large before the shell becomes too thick and the embryo suffocates. That meant there had to be a huge difference in size between some adult dinosaurs and their young. According to Nature, Asian elephants give birth to calves 25 times smaller than them. But an infant titanosaur could be 2,500 times smaller than its parents. Some titanosaurs were as long as four double-decker buses.
So, unlike mammals, dinosaurs existed across a huge size range as they grew up. According to the new study, these baby dinosaurs occupied the evolutionary niches that would otherwise have been available for medium-sized dinosaurs. Only the giants – and their pint-sized young – survived. By contrast, there were all sorts of small early mammals. Think of the cartoon blockbuster Ice Age, with its trio of mammal protagonists: the diminutive Scrat, Sid the mid-sized ground sloth and Manny the mammoth. They’re not just drawn that way.
Now being the biggest animal that ever walked the earth must have felt pretty good at the time. No doubt the titanosaurs didn’t much care if there were fewer of their smaller relatives around any more. But in a crisis, big turned out to be fatal. The asteroid landed at Chicxuclub, the Deccan Traps erupted, suddenly the world was a hard place to make a living in for a big beast. The small and nimble won out – not just the mammals but also those dinosaurs that had avoided their offspring by taking to the air, the first birds.
Sometimes nature writes its own allegories for us. There shouldn’t be too much surprise in that: the emergent processes of evolution and the emergent order of the marketplace are close cousins. Today, with renewed talk of centrally-mandated industrial policy and a coalition government obsessed with picking which energy technologies are fated to triumph, when fears of financial meltdown are met by a determination to force everyone into a single too-safe-to-fail regulatory corset, the merits of the small and the diverse are out of fashion. The belief that one big right answer will save us is tempting. It can for long periods of time look like the king of the world. But the future is dark, the unexpected always happens in the end and a marketplace of many solutions of all kinds and sizes will thrive when even giants despair.