Archaeopterix

[Mike Bonham <bonham@jade.ab.ca>]

KBoyat@aol.com wrote:
>      I came upon an interesting article today in "Earth" magazine. It seems
> there is some debate now over the ability of archaeopteryx to fly.
>      According to University of Aberdeen zoologist John Speakman, the feathers
>  of archaeopteryx  were not asymmetrical enough to provide the proper lift
> for the ave/ reptile. He based this on a study of present day birds, both
> fliers and the flightless, and concluded that the position of the central
> shaft of the feather in archaeopteryx put it in the realm of the flightless
> birds.
> ...
>     It still leaves the nagging question of why archaeopteryx would evolve
> asymmetrical in the first place.

They could be the degenerate form of a flight-capable ancestral bird,
having taken the first evolutionary steps toward complete flightlessness.

That would be interesting, because there are affinities between Archaeopterix
and the long-armed maniraptor dinosaurs, most of which date from AFTER
Archaeopterix's appearance in Jurassic strata (don't they?)

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!

Is there any plausibility to this idea?  Could Archie's features be
considered primitive w.r.t. mainstream maniraptorans?  Are there ancestors
known for the earliest maniraptors, antecedent to the Solhofen deposit?

Sorry if this is tediously naive speculation, but you must admit
this idea would be interesting if true (and interesting anyway?)

Mike Bonham        bonham@jade.ab.ca      Jade Simulations International