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in Pittman, Kaye, Campos & Habib, 2022. Artwork by Julius T. Csotonyi |
Abstract
Pterosaurs thrived in and around water for 160 + million years but their take-off from water is poorly understood. A purportedly low floating position and forward centre of gravity barred pterosaurs from a bird-like bipedal running launch. Quadrupedal water launch similar to extant water-feeding birds and bats has been proposed for the largest pterosaurs, such as Anhanguera and Quetzalcoatlus. However, quadrupedal water launch has never been demonstrated in smaller pterosaurs, including those living around the Tethys Sea in the Late Jurassic Solnhofen Lagoon. Using Laser-Stimulated Fluorescence, we singled out aurorazhdarchid specimen MB.R.3531 that alone preserved specific soft tissues among more than a dozen well-preserved Solnhofen pterosaur specimens. These soft tissues pertain to primary propulsive contact surfaces needed for quadrupedal water launch (pedal webbing and soft tissues from an articulated forelimb) that permit robust calculations of its dynamic feasibility without the need to make assumptions about contact areas. A first-principles-based dynamics model of MB.R.3531 reveals that quadrupedal water launch was theoretically feasible and that webbed feet significantly impacted launch performance. Three key factors limiting water launch performance in all pterosaurs are identified, providing a foundation for understanding water launch evolution: available propulsive contact area, forelimb extension range and forelimb extension power about the shoulder.
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| Skeleton and associated soft tissues of the aurorazhdarchid pterosaur specimen MB.R.3531a. (a) White light image of slab. Scale = 20 mm. (b) LSF image of slab. Soft tissues visible under white light are clearer under LSF, whilst speculative soft tissues under white light are confirmed by the technique. Otherwise invisible soft tissues are also revealed under LSF. |
Michael Pittman, Thomas G. Kaye, Hebert B. Campos and Michael B. Habib. 2022. Quadrupedal Water Launch Capability Demonstrated in Small Late Jurassic Pterosaurs. Scientific Reports. 12: 6540. DOI: 10.1038/s41598-022-10507-2