Capacity for the Cretaceous pterosaur Anhanguera to launch from water

Abstract

Many large pterosaurs come from marine sediments. While the feeding ecology of large pterosaurs is contentious, it is likely that some species took food from the water surface. As a result, it is likely that some pterosaurs were forced into the water through stochastic events. Unless a water launch was possible, such events would presumably be lethal. Here I present the results of a quantitative and comparative morphological analysis of the large marine pterosaur Anhanguera santanae that suggest this animal could launch from water, without the assistance of wind or waves, using a form of quadrupedal takeoff. Initial escape from the water surface would use the most energy and could be accomplished with a net remaining acceleration of 17 m/s2, with an acceleration of up to 39 m/s2on the subsequent series of repeated propulsive bounds, which would have occurred as a series of “hops” across the water surface. While the capacity for such a behavior is not demonstration that such it was utilized, this species possessed a wide array of anatomical features that would make water launch both efficient and effective, and cannot be easily explained as adaptations to flight or walking: the expanded scapula, reinforced scapular‐notarial joint, warped deltopectoral crest, exceptionally broad MCIV‐PHIV wing finger joint, and expanded posterior brachial musculature. Funding provided by the Jurassic Foundation.