Days or Nights

Small pterosaurs ruled the skies until birds took flight and edged them out. They did this much as birds do now; during the day and night and all hours in between. Many of the smallest pterosaurs discovered and described from the Triassic and Jurassic have been examined thoroughly and they have been described alternately as being dirunal or nocturnal based on the sclerotic rings that remain in the fossilized crania. Sclerotic rings encircle the eyes and their size can be correlated with the missing soft tissues. The overall size of the eyes, orbits, and sclerotic rings all allow for inferences about the lifestyle afforded by the eyes of the particular pterosaur in question. The eyes of Scaphognathus indicate that the pterosaur was diurnal. The similarities between Scaphognathus and the contemporaneous taxa Rhamphorhynchus and Ctenochasma also lend themselves to inferences of the time of day in which the animals were active. Rhamphorhynchus and Ctenochasma are hypothesized to have been mostly or strongly aligned with a nocturnal lifestyle. Similar diets shared between the three taxa living different lifestyles makes niche partitioning a likely scenario. Seeing fossil ecology put into practice in this way is not frequent, but when we do get to paint that sort of scenario it is special and quite intriguing.

©Dmitry Bogdanov