[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Of course nonavian dinosaurs could fly - duh
G.S. Paul <GSP1954@aol.com> wrote:
> Who could have predicted it? The mainstream, cladistic based consensus
> saw the origin of dinosaur-avian flight as a fairly simple
> affair with nonavian, nonflying, ground running Jurassic theropods
> learning to fly via Archaeopteryx type birds from the ground up.
I have to disagree this statement. The results of cladistic analysis do not
mandate a "ground-up" origin of flight. They never have. Rather, the
well-supported phylogenetic hypothesis that the bird clade (Avialae) is the
sister taxon to Deinonychosauria (dromaeosaurids + troodontids) is open to
various ecomorphological hypothesis for the origin of flight: "ground-up",
"trees-down", or (most likely) something in between these two extremes.
I only point this out, because for too long a theropod origin of birds (a
phylogenetic hypothesis) has been equated with a "ground-up" origin of avian
flight (an ecomorphological hypothesis). This may have once been the case
(such as back in the 1960's and 70's). But over the past 20-30 years, the old
"trees-down" versus "ground-up" dichotomy has been replaced by a more nuanced
view of the origin of avian flight, with an acceptance that both
cursorial/terrestrial and arboreal behaviors might have played roles in shaping
the avian flight apparatus.
> So now we have
> an apparently arboreal,
> sickle-clawed deinonychosaur with airfoils from earlier
> than Archaeopteryx,
> with the implication that latter nonvolant deinonychosaurs
> were secondarily
> flightless? Yes, who could have predicted such a thing?
I don't see why _Anchiornis_ is "apparently arboreal". I guess to some degree
it depends on one's definition of "arboreal". To me an "arboreal" animal is
one that spends most of its life in trees. I don't see any evidence of
arboreal specializations in the anatomy of _Anchiornis_; or in _Archaeopteryx_;
or in the microraptorines. Sure, they might have ventured into trees. But
then again, so do some modern ground-hunting birds that are specialized for a
I wonder how _Anchiornis_ compares with _Jinfengopteryx_? Or _Yandangornis_?