[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Tiktaalik


----- Original Message ----- From: "T. Michael Keesey" <keesey@gmail.com>
To: "Dinosaur Mailing List" <dinosaur@usc.edu>
Sent: Thursday, April 06, 2006 2:07 PM
Subject: Re: Tiktaalik


what if gigantic 
adult pterodactyloids (like _Quetzalcoatlus_) were flightless? What if
they were fliers when young and segued into a more and more
terrestrial niche as they grew? That would remove the problem of
getting those gigantic things to take off.

There's no particular problem in getting the big guys off the ground. They don't appear to me to launch like birds, and skeletal bracing in the more heavily loaded ones appears to me to be oriented more toward launch loads than flight loads. It would appear that either morph of Quetzalcoatlus could launch at will in a dead calm, even in today's atmosphere. And do it well enough to get off from my front yard -- which is not large -- tiny even. Average acceleraton during launch would be on the loose order of 2 g's. The wing morphs between Q species and Q northropi indicate that northropi could probably launch as well as, and fly better than species. My numbers seem to indicate that species probably wouldn't soar quite as well as a wandering albatross, and that northropi would soar a bit better. Note though, that albatrosses are primarily marine, and quetz appears to have been an inland, fresh water feeder. Primary sources of atmospheric energy for flight would have been different. Both morphs of quetz would have been durned effective at migrating, and I'd speculate that they did so.

I suppose a testable prediction would be adult forms more adapted to
terrestriality than juvenile forms--I don't know if there's an
appopriate ontogenetic series anywhere, though.

All of the Quetz remains that I'm personally familiar with, are adults. The adults are adapted as durned good flyers -- and even northropi and Hatzegopteryx aren't all that close to the upper size limit for a pterosaur though (based on the deltopectoral crest), I'd say northropi was likely a more powerful flapper than Hatzegopteryx.

As an aside, not all the Quetz skull material is crushed flat laterally, and they are reasonably narrow from side to side. My take on the skulls and lower mandibles is that they have some pretty neat hydrodynamic features that would be very effective for skimming.