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Re: [...] Archaeopteryx 10
Forwarded with permission, my comments interspersed...
> "Bird", if the Mayr et al
> study is worth anything, is a form taxon with no
> phylogenetic merit if one includes the fossil
You're way too pessimistic :-)
Nahhh, I mean the vernacular term alright. Not
"avian", "bird". Basically the "fundament" for BCF - a
confusion between the form taxon and the taxon. I'm
completely optimistic that much if not most of Aves
will turn out a proper clade (because most of Aves
already IS - Neornithes). But critters like Rahonavis
were and still are overused by BCF proponents and the
likes, and media nerds, to expand "bird" to the
breaking point and beyond. "Bird" (as it's not a
scientific term) has come to mean "flying feathered
'reptiles'", and suggesting Birds = Aves runs one into
all sorts of trouble.
I disagree. "Birds" cannot be separated from "Aves" because that's what
"Aves" means -- not just in Latin, but also in Spanish and Portuguese.
Trying to separate them would produce all sorts of trouble (that is,
mistakes even in the primary literature). We just need to make sure the
taxon remains monophyletic -- and that's easy, of course.
BTW, why do you speak of "BCF proponents" in the plural? :->
I don't see anything that could pull
*Confuciusornis* out of its position
I retract my statement for the time being. C. still
troubles me. That all "bird" lineages seem to have
some sort of Archie at the time when powered flight
took hold - no matter how many such "proto-birds"
there were - appears increasingly certain. But if C.'s
Archie-like progenitor *was* something roughly
contemporary with Archie - which seems just possible
because the speed of anatomical finetuning is unknown
-, it is more unlikely than not that this ancestor was
shared with Neornithes. Confuciusornis seems
aerodynamically refined to a degree comparable to but
differently from some crown group members of the
Neornithean lineage; the wing shape was much more
adapted to a certain mode of flight than any
galliform's ever was.
Isn't *C.* just adapted to its lack of an alula?
Compare Gansus, which was a
crude flyer by comparison to C.
Of course a scenario where C. was simply the product
of strong ecomorphological selective forces cannot
be rejected at present, but its skull, beak, etc.
By and large and
as far as the fossil record is unequivocally placed,
the neornithean lineage and its Late Mesozoic
ancestors used flight more or less to get about, as a
means of locomotion and not too much else, until the
Paleogene. C., on the other hand, made a living from
it, and it seems unlikely given the competition that
it could make a living from anything else.
Those enormous 1st and 3rd finger claws can't have been adaptations to
Avebrevicauda alright - but that's not all too
interesting, except maybe as seen from the NAT side
(to which aspect I'm far to novice to contribute much)
Do you know offhand what the plesiomorphies of C.
The same as the apomorphies -- together with *Changchengornis*, it's the
sister-group of (Ornithothoraces + *Jibeinia* + maybe a few more).
I haven't been able to look in the
"dino" part of it very much, because the apomorphies
have received considerably more attraction; research
seems to have been shaped considerably by the
assumptioin that it's "a bird, and that's that". The
shoulder (?coracoid?) and the "diapsid skull" papers I
have around, but that's about it as far as
plesiomorphies are concerned.
The scapula and the coracoid are fused. Together with the sutured ones of
*Sapeornis*, this indicates that the joint between these bones, shared by
(Ornithothoraces + *Jibeinia*), *Rahonavis*, and *Shenzhouraptor* & friends,
probably evolved at least twice.