PADIAN, K.*; MAZIN, J.-M.; BILLON-BRUYAT, J.-P.; Univ. of California, Berkeley; Univ. of Poitiers, France; Univ. of Poitiers, France: How pterosaurs landed: the first evidence from footprints

Pterosaurs, the first known flying vertebrates, were closely related to dinosaurs and contemporaneous with them during the Mesozoic Era (Late Triassic � Late Cretaceous, about 220-65 million years ago). Although questions about their posture and gait persist, pterosaurs had erect posture and a parasagittal gait, as revealed by functional studies and footprints reported since 1995. These footprints, which come from the Late Jurassic of southern France, show that pterosaurs were capable of walking and even running quadrupedally. The manus print generally occurs outside the pes and slightly behind it. So as not to interfere with the wing, the manus was raised before the ipselateral pes proceeded. The trackway pattern was LF-LH-RF-RH, contrary to the common tetrapod pattern (LF-RH-RF-LH). This pattern and other features suggest that pterosaurs were only secondarily quadrupedal. We report the first known trackway of a pterosaur landing. These also come from the Late Jurassic sediments of Crayssac, France. In this sequence, the pterosaur, a small pterodactyloid (pes length = 5 cm), did not make a running landing. Rather, it apparently stalled before landing to slow its descent and speed, because the distance between successive footfalls is so short. It touched the ground lightly on its heels, scraped its claws as it continued forward, and landed on its feet. It then placed both manus on the ground. This was followed by a short step of adjustment by all the feet; then the animal began to walk normally. These functions are consistent with those of many extant birds and bats when landing on the ground.