Re: Archaeopterix

["Taylor,Rod;=8728883" <RODT@kean.ucs.mun.ca>]

> Lets see where this takes us:
> In the early Jurassic, a branch of the theropods evolves feathers and flight,
> producing birds.  One branch of early birds GIVES UP flight, producing
> Archaeopterix and evolving into more highly developed flightless maniraptoran
> dinosaurs.  These guys survive the Jurassic-Cretaceous extinctions and move
> into the space vacated by the allosaurs.  In the mid-Cretaceous, a branch of
> the maniraptors gives up long arms and becomes gigantic.  Thus, in this
> scenario you could say Tyrannosaurus evolves from birds!
> 
> Mike Bonham        bonham@jade.ab.ca      Jade Simulations International
> 
> 
One fact seems to be regularly forgotten in these Archie discussions 
whenever they occur - he/she couldn't have 'flown' in the trus sense.  No 
keel!  That rather large, cartilagenous hunk of white stuff that all the 
white meat is attached to on your Christmas turkey (no sarcasm intended - 
sorry in that came across the wrong way!).  In the fossils of 
Archaeopteryx I've seen, I've never seen traces of the keel, which is an 
anchor for the large muscles required to power wing-driven flight.  Now, 
this doesn't answer to the possibility that Archie was a glider - just 
hold those suckers out there, and let the currents carry you out there.  
But this would reflect on them being able to get to areas where they 
would be able to take advantage of these currents, i.e. climbing trees.

Oh, what a tangled web we weave...


Rod Taylor
Earth Sciences Dept.
Memorial University of Newfoundland