During much of the early part of their evolutionary history, they were pretty much everywhere. But as the earth started to cool, particuarlyr roundabout sort of 30 million years ago onwards, the range of crocks really shrank. And so we do really seem to see that their diversity does seem to tie in with how climate has changed across the globe. I think angele is probably right. They probably were just limited r somehow, so not being able to take advantage of niches. We don't find any crocks living in trees. We deafly don’t find any of them flying.
Melvyn Bragg and guests discuss the remarkable diversity of the animals that dominated life on land in the Triassic, before the rise of the dinosaurs in the Jurassic, and whose descendants are often described wrongly as 'living fossils'. For tens of millions of years, the ancestors of alligators and Nile crocodiles included some as large as a bus, some running on two legs like a T Rex and some that lived like whales. They survived and rebounded from a series of extinction events but, while the range of habitats of the dinosaur descendants such as birds covers much of the globe, those of the crocodiles have contracted, even if the animals themselves continue to evolve today as quickly as they ever have.
With
Anjali Goswami
Research Leader in Life Sciences and Dean of Postgraduate Education at the Natural History Museum
Philip Mannion
Lecturer in the Department of Earth Sciences at University College London
And
Steve Brusatte
Professor of Palaeontology and Evolution at the University of Edinburgh
Producer Simon Tillotson