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Craig Muhonen wrote:https://www.livescience.com/24071-pterodactyl-pteranodon-flying-dinosaurs.html
Unfortunately, many of the details given in this weblink do not quite reflect the current paleontologic understanding of pterosaurs:
- The video shows a Pterodactyl that bipedaly walks, jogs, runs and finally lifts off -- very much like a modern swan or an albatross does. However, this kind of launch would be totally impossible for a pterosaur. Its hind legs are relatively short and located quite a bit behind the centre of gravity. As a consequence, a Pterodactyl would have to assume an upright posture to not topple over -- very much like a running human. However, this is incompatible with spreading their wings for flight. In addition, the legs of pterosaurs are missing areas where massive muscles for a powerful sprint would have attached. This is very much unlike the anatomy of modern birds. (See the size of chicken thighs...) The solution to this puzzle is a quadruped launch mode. That is, using all four limbs to jump into the air. That way, the brunt of the acceleration at launch is accomplished by the muscles that also flap the wings. See this video for a realistic reconstruction of a pterosaur launch: https://www.youtube.com/watch?v=ALziqtuLxBQ
- In the video of the weblink the pteroid bone points toward the body. This is an extra bone exclusive to the pterosaurs that attached to the "hand" of the wings. However, careful investigation of the joints reveals that the bone was oriented forward and increases the wing area in front of the humerus. This works similar to like slats on modern aeroplanes. See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1560000/ for the details.
- In flight, the wing bones of the Pterodactyl skeleton are shown to stretch orthogonally from the spine. However, this would place the centre of lift far behind the centre of gravity. The pterosaur would instantly enter a tumble. A realistic soaring posture puts the wings in a forward pointing position.
- When in flight, the pterodactyl skeleton points its beak straight ahead -- very much like a modern day stork. However, after looking at the details of the neck vertebrae and even the orientation of the vestibular system palaeontologists concluded that pterosaurs kept their head downward.
- On landing, the pterodactyl skeleton casually strolls along the ground while gently flapping its stretched wings. If landing a 10 m span glider were that easy there would be much less "whack" of modern HG.
- The drawing of the Pteranodon in flight shows a structure at the trailing edge of the wing that stretches the membrane like an umbrella or like the finger bones of a bat. However, there are no such membrane stretching bones on a pterosaur.
- Birds did not "descend from" dinos. They are the surviving branch of the clade Dinosauria.
All the best,
---<)kaimartin(>---
