[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Combined answer Archaeopteryx running...
Comments to 2 posts from HP Jim Cunningham:
> As you no
> doubt know, modern birds can fly in cruise gaits with their
> cut through (meaning that it is even less useful than in archie).
They just can't gain height any longer. No idea whether Archie's deltoideus
> > Now we're talking 'cruising'. For a primitively poor flier that
> > couldn't flap well, this would just be 'gliding', wouldn't it?
> No. [...] And what would
> make you think he was primarily a glider? His glide ratio isn't
> as good as that of a pigeon; it isn't all that bad either, but I
> wouldn't expect him to make a living at it, just like a pigeon isn't
> good enough at to make a living with it.
There's even a calculation -- but it only takes into account the weight of
the tail, not its area, and the assumed wing area is debatable -- that
Archie would have reached about 12.9 m/s during gliding. The impact would
Klaus Ebel: On the origin of flight in *Archaeopteryx* and in pterosaurs, N.
Jb. Geol. Paläont. Abh. 202(3), 269 -- 285 (December 1996)
> > ......opposed to ........ "_Archaeopteryx_-grade" avians. The latter
> > did (apparently) persist until the end of the
> > Cretaceous (_Rahonavis_); but they were outnumbered
> > (and outcompeted) by the upstart pygostylians.
> Since they lasted till the end of the Cretaceous, it may not have been
> the pygostylians what done um in.
I agree. What could have competed with the specialized *Rahonavis*?