Flying reptiles that went extinct around 65 million years ago probably did not spend much time on water — even though fossils of the creatures with fish in their stomachs have been found in ancient oceans and lakes.

David Hone, at Queen Mary University in London, and Donald Henderson at the Royal Tyrrell Museum of Palaeontology in Drumheller, Alberta, tested the floating-pterosaur hypothesis by creating computer models of what four pterosaurs might have looked like afloat. They took account of the reptiles' bone density, skeleton shape and other factors. The models suggest that, under most conditions, pterosaurs would have oriented their heads horizontally to the water, leaving the bottom one-quarter to one-third of their heads submerged.

Pterosaurs would have risked drowning if they spent too much time on the water, the researchers say.

Palaeogeogr. Palaeoclimatol. Palaeoecol. (2013)