Costa et al review the literature on pterosaur biomechanics

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Figure 2 shows an Anhanguera pelvis and femur with axes of rotation not aligned. Get those axes aligned first. Then discuss stance. Same for figure 3 (Quetzalcoatlus) which is restored with weight on the forelimbs. Treat the forelimbs like ski poles and match the restoration to ichnites. In pterosaurs (all former bipeds) the feet plant beneath the center of gravity = balance, That enables the wings to lift off the ground for flapping, whether for flight or not. The authors mention ‘large sternum’ without understanding, as Wild learned from Triassic taxa, that its a sternal complex, created by the merging of the interclavicle, clavicles and sternum. No mention of pterosaur origins other than ‘protopterosaur’. Quoting: “Flight precursors of birds, winged mammals and pterosaurs have probably evolved from a parachuting and gliding stage (as modern flying squirrels) to an active flight mode that could sustain a wing-flapping flight for a long time.” Don’t use the word ‘probably’. This is not guesswork. This is science. Cosesaurus, Sharovipteryx and Longisquama all have a sternal complex, with bird-like elongate coracoids. These, by analogy with birds (and bats if you look at the mechanically similar clavicle) are what turn typical tetrapod right-left walking with the forelimbs into symmetrical up-down flapping. Workers are missing this key point. Learn it. Conclusion: This was a review, which means if you know the literature, you’ve seen this all before. Figure 6 promotes the myth of quadrupedal launch, which involves placing the wing finger in contact with the ground. All manus ichnites of pterosaurs show the three free fingers and no trace of the wing finger. So figure 6 cheats pterosaur morphology. Just let pterosaurs stand up, like a bird, spread those wings, like a bird, flap and leap like a bird for maximum thrust at takeoff. The quad launch hypothesis depends on cheating pterosaur anatomy. Reject this hypothesis.

Costa FR et al 2025. Gaining ground on pterosaur biomechanics: A general overview. An Acad Bras Cienc (2025) 97(Suppl. 1): e20250490 DOI 10.1590/0001-3765202520250490
Anais da Academia Brasileira de Ciências

Annals of the Brazilian Academy of Sciences Printed ISSN 0001-3765 I Online ISSN 1678-2690

https://www.scielo.br/j/aabc/a/GGdL5Zn6XYNPCR6rxwCvTQB/?lang=en