Tuesday, April 27, 2010

Pterosaur and Modern Bird Correspondences

Let's begin with a preliminary list of pterosaur/bird correspondences. Consider the albatross, the stork, the pelican and the condor/vulture. (In fact, it is very easy to picture a condor and imagine that you are looking at the feathered version of an actual pterodactyl).

Two of the taxa (groups) within Pterodactyloidea are Ornithocheiroidea and Azhdarchoidea.

Within Ornithocheiroidea are Pteranodontids which are similar to the modern day albatross.
"The wing shape of Pteranodon suggests that it would have flown rather like a modern-day albatross. This is a suggestion based on the fact that the Pteranodon had a high aspect ratio (wingspan to chord length) similar to that of the albatross — 9:1 for Pteranodon, compared to 8:1 for an albatross. Albatrosses spend long stretches of time at sea fishing, and utilize a flight pattern called "dynamic soaring" which exploits the vertical gradient of wind speed near the ocean surface to travel long distances without flapping, and without the aid of thermals (which do not occur over the open ocean the same way they do over land)."

Within Azhdarchoidea are azhdarchids which are considered by researchers to be "stork- or ground hornbill-like generalists".
"However, azhdarchid footprints show that their feet were relatively small, padded and slender, and thus not well suited for wading. We argue that azhdarchids were stork- or ground hornbill-like generalists, foraging in diverse environments for small animals and carrion".


"According to scientists and paleontologists, the Rhamphorhynchus hunted in a manner similar to the modern-day pelican wherein it would dive into water and use its long beak to scoop out fish, insects and frogs from water and then toss them down its throat pouch.
The fossils of Rhamphorhynchus that have been found have been well-preserved. One can see not just the skeleton but also the outline of the internal organs. Some fossils have been found with the throat pouch intact. Many Rhamphorhynchus fossils have been found in southern England and in Bavaria in southern part of Germany."

"Throat pouches (like those of a pelican) can be seen in Pterodactylus and can be inferred in Ludodactylus."

"Rhamphorhynchus probably ate fish and it is believed that one of the ways it hunted was by dragging its beak in the water, catching fish and tossing them into its throat pouch, a structure similar to that of pelicans, which has been preserved in some fossils. This method of catching fish is found today in skimmers."

"Unlike many of the other Pterosaurs Quetzalcoatlus lived inland and probably had a vulture-like existence. It's long neck would have helped it to "probe" dinosaur carcasses for meat.
Others think they may have been carrion feeders, like modern vultures, and fed upon the carcasses of dinosaurs. Their long beaks and necks made them capable of probing deeply for food, on sea or land."


Reconstructed wing planform of Quetzalcoatlus compared to the Wandering Albatross and the Andean Condor

"Based on Mark Witton's research (he's the most decent pterosaur paleobiologist I've seen so far), here's a brief comparation between pterosaur and bird niches (note: niches occupied as adults; since pterosaurs were precocial, they occupied several niches throw their lifestyle, and I have no idea what can be said about them):

-Azhdarchoids: storks, teratorns, ground hornbills, bustards, secretary bird/seriema, herons, galliformes
-Dsungaripteroids: oyester catchers, open bills storks
-Ctenochasmatoids: shorebirds, flamingoes, seagulls
-Ornitocheiroids: albatrosses, frigate birds, pseudodontorns, vultures
-Advanced "basal" pterosaurs (Rhamphorhynchus & kin): same as above (only to a smaller scale), except for the vulture niche; they probably produced falcon like things though.
-Anurognathids: nightjars
-Dimorphodontids: hawks, owls"

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