The splayed leg bipedal locomotion AND flapping before gliding problems answered here

Images and links continue to be on the fritz.
So here’s a reply to a recent comment.

Stu Bonk indicates splayed hind limbs (which happens when the axes of the acetabulum and femoral head align) would have a limited range of motion in pterosaurs. Please see: https://pterosaurheresies.wordpress.com/2021/12/10/sharovipteryx-running-animation/

More info on that anhanguerid pelvis here:

Anhanguera pelvic girdle and femur orientation

and pay attention to that YouTube video of a running lizard by the Bruce Jayne labs on that page. Note the wiggling of the hips during each stride AND the wide placement of the feet in dorsal view.

Other bipedal lizard videos online here: https://www.youtube.com/results?search_query=bipedal+lizard

Stu Bonk also wrote:
“Why would Cosesaurus flap when it has none of the tissue that pterosaurs have? With non-avian dinosaurs, the ones who might have flapped had pennaceous feathers which, for most of them, could be used for some level of gliding, stabilization, display, etc. but Cosesaurus lacks the membrane so there would be no reason for it to flap.”

Why questions are left to speculation:
So, imagine this little guy trying to get a date and ward off rivals and enemies. Flapping for the first time on Earth might impress everyone. Contra your guesses we do know that Cosesaurus had immobile and elongate coracoids + a strap-like scapula attached to a sternal complex = sternum + interclavicle + clavicles, as in pterosaurs, which fused the elements more or less completely. Birds have such coracoids. They indicate flapping. Bats have elongate clavicles because they lack coracoids. Cosesaurus does have trailing membranes on the forelimbs. Also a pteroid. Ellenberger also saw them.

Theropods flapped before flying, like fat chickens, I imagine.

Sorry you’ve been misled by other workers
that gliding came first in birds, bats and pterosaurs. The anatomy indicates flapping came first. You can flap with little wings before you can glide. And gliding is not a forelimb active mode. Thus, these animals needed to develop flapping first.

Sorry you’ve been misled that pterosaur wing membranes
extended to the ankles, as in dermopterans and flying = gliding squirrels. The fact is no one has ever discovered such a pterosaur. If so, I beg you to send me a photo of the specimen. In counterpoint all pterosaur wings stretched between the wingtip and elbow, with a small fuselage fillet back to mid thigh. This is for flapping, but also enables glider plane-like gliding. Long wings came last. Flapping tiny forelimbs came earlier, along with bipedal locomotion and the loss of the short, round sliding coracoid common to other lepidosaurs and basal tetrapods in general – exceptions (birds, bats, pterosaurs) noted above, plus snakes, etc.