Monday, May 16, 2011
There's been a lot of debate about Confuciusornis lately. Could it fly? If so, how? And how well? It probably wasn't doing anything like a modern bird does. Studies of its feather strength suggest it couldn't do more than glide (or could it?). But studies of its forelimb and shoulder girdle show it couldn't lift its arm much above the horizontal plane, making flapping pretty much impossible. Unless that huge, fenestrated deltopectoral crest gave it a rather unique flight stroke that only minimally involved the humerus.
Or, maybe this was a small theropod with enormous, high-aspect ratio wings larger than those of any other early bird, with asymmetrical feathers, puny feet and short legs ill suited for running and a small, barely reversed hallux ill suited for climbing, which couldn't flap and could barely glide with its thin feather shafts, yet is consistently found preserved as enormous flocks at the bottom of deep lake deposits. In which case the giant wings would be for display, obviously, to hopefully impress a predator so much that they decline to eat the poor bird which has no means of escape or defense other than to flee into the depths of the water like a 1960s brontosaur, only to remember that it also can't swim. No wonder they're extinct! Anyway... I hope much, much more study (and some wind tunnel tests) will eventually help untangle this mystery. For now, I was struck by something a little more frivolous. Working on a lateral view of Confuciusornis sanctus, checking and re-checking papers to make sure proportions are right, it started to look unmistakably like the profile of a... rhamphorhynchid pterosaur? Between this, and basal paravians with expanded, diamond-shaped vanes on the tips of their tails, in terms of general body plan there are some curious similarities (convergences?) between the first gliding/flying birds and primitive, long-tailed, high-aspect ratio-winged pterosaurs. My PhyloPic style silhouette version above.