Ancient animal behaviour: Jurassic lark PALAEOETHOLOGY, working out how long-extinct animals behaved, is a subject whose practitioners can never, definitively, be proved right. But that does not stop them trying. The latest effort, to be presented later this month to the International Symposium on Pterosaurs in Rio de Janeiro, is an attempt by Michael Habib of the University of Southern California, in Los Angeles, and Mark Witton at the University of Portsmouth, in Britain, to work out how one of the most peculiar of the flying reptiles of the Jurassic earned its living. Anurognathus and its relatives have been known for 90 years. They were the size of swifts and until now it had been thought that, like swifts, they chased around the sky after insects - a technique known as hawking. Dr Habib and Dr Witton believe this is wrong. They suspect instead that Anurognathus sat in wait for its prey, and then sallied forth to intercept it like a surface-to-air missile. They came to this conclusion by comparing Anurognathus with 36 birds and 20 bats from the Smithsonian Institution in Washington, DC. Using a mix of computerised tomography and mundane measurements with callipers, they assessed the lengths, widths, thicknesses, densities and bending potential of the bones of the modern animals and compared them with those gleaned from Anurognathus fossils. Anurognathus's mouth, they found, was similar to the mouths of nightjars, which also sally after prey (though they do hawk as well). Moreover, the pterosaurs" legs and wings were stronger than those of any comparable bird or bat, reinforcing the idea that they could leap rapidly into the air. Their conclusion was that Anurognathus did indeed feed by sallying - and probably more effectively than any living creature.