The rule of the reptiles

Abstract

In the Triassic, change came: the archosaurs or ruling reptiles appeared, and many of the mammal-like beasts became extinct. Perhaps today’s most familiar large carnivorous reptile is the crocodile. One of the diversions of geological field work in Africa is to sit hidden on a river bank, very still, and watch for what are locally called ‘flat dogs’ or, in deference to Western consumer tastes, ‘handbags’. The signs are obvious — little mounds of fish teeth, ‘croc drops’ — but the animal is not obvious. At first, all that can be seen is the spouting and humping of hippos, but eventually two nostrils appear, if the scene is peaceful, and then slowly the eyes and head of a wary reptile float across the pool. Crocodiles are cunning and superb at concealment; they are also marvellous parents, carefully taking up their young in their mouths to move them (from which action comes an old, false, accusation that they are cannibal). Somehow the crocodiles have survived: other reptiles went on to greater things, and perished.