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Re: Greg Paul is right (again); or "Archie's not a birdy"... but Jeholornis is (not!))
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- Subject: Re: Greg Paul is right (again); or "Archie's not a birdy"... but Jeholornis is (not!))
- From: Tim Williams <email@example.com>
- Date: Mon, 8 Aug 2011 11:12:32 +1000
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Before I respond to GSP's post, I think it's pertinent to mention that
this thread began as "Greg Paul is right (again)" because a single
phylogenetic analysis with a single new taxon (_Xiaotingia_) recovered
_Archaeopteryx_ inside the Deinonychosauria clade, and outside the
line that led to modern birds. This accords with GSP's long-held
views on the position of _Archaeopteryx_ vis-a-vis deinonychosaurs -
hence the ensuing victory lap on the DML. But if another analysis in
the future (perhaps one that uses an expanded dataset) fails to find
support for this topology - will that prompt a message entitled "Greg
Paul is wrong (again)". I hope not, because that seems awfully unfair
to GSP. It also seems irrelevant, because GSP does not subscribe to
cladistic methodology, so it seems odd that a phylogeny based on a
methodology that he derides could be cited in support of a
non-cladistic, intuition-driven hypothesis advocated by GSP.
> T has apparently he has taken it upon himself to define birds as being
> those dinosaurs that have developed advanced powered flight with maybe
> ability thrown in. Well I'll be darned, you learn something new every day
> since I have never seen high level powered flight used as the defining
> character of the group. For example Archaeopteryx since the mid 1800s was
> considered a bird even though it has always been clear it has limited flight
> (although it was no mere glider has I have repeatedly demonstrated in the
> technical literature).
Oh pish-posh. I said nothing of the sort. I'm not interested in
defining what is (or is not) a "bird". What I'm saying is that when
it comes to defining what a "bird" is, saying it's something that has
"wings and a short tail" is as arbitrary as any other definition of
"bird". These "wings" and "short tails" were likely employed for
different functions, depending on where on the Maniraptora tree the
particular taxon sits. As a case in point, the wings and short tail
of _Sapeornis_ were likely employed for a very different purposes to
the wings and short tail of a pigeon.
In the end, it doesn't matter what you or I call a "bird". What
matters is how this array of fossil taxa document the construction of
the avian flight apparatus. Along the way there were probably many
detours and dead-ends. So simply claiming that "wings" and a "short
tail" are what maketh a bird is potentially dangerous, because it
implies that these anatomical traits were employed in the same manner
as those of modern birds. For that reason, I think the idea that
non-ornithothoracean avialans should be referred to as "protobirds"
makes a lot of sense.
> The notion that all birds must be strong fliers will not fly. Also note
> that ?????????? criticizes defining birds (vernacular, not Aves) as belonging
> to the clade with surviving members that evolved stub tails is iffy because
> it is difficult to define what is a short tail,
Ummm.... what? Yes, I did say that a "short tail" is hard to define.
What I also said is that trying to use the presence or absence of a
short tail as a defining character of "bird" (in the vernacular sense)
is hogwash. Ditto for "wings" (whatever that word might mean - for
example, do the feathered forelimbs of _Caudipteryx_ qualify as
BTW, you seem to have a pointed aversion to mentioning my name.
Initially I thought you were just being discourteous; but then it
occurred to me that you might be a huge Harry Potter fan and be
equating me in some way with Voldemort - hence referring to me as 'T'
or '????????' or 'He-Who-Must-Not-Be-Named', because you were too
gripped with fear to mention me by name.
> but his definition of powered
> flight (and perching) is also ill defined because there is no way to
> determine exactly what had or did not have the specific degree of powered
Yeah, agreed. So when it comes to evaluating the potential flight
abilities of fossil "winged" theropods, I would advocate a
conservative approach. Unless there is compelling anatomical evidence
to support a "winged" theropod being capable of powered flight, then
there is no reason to assume that it *did* fly simply because it
"looks like a bird".
Frankly, I don't believe that deinonychosaurs or oviraptorosaurs were
"neoflightless". (As an aside, have I mentioned how much I hate the
word "neoflightless"?) As I said in my previous post, recent evidence
points to exceedingly poor flight abilities (if they were capable at
all) in any and all taxa outside the Ornithothoraces. So stretching
flight abilities to the base of the Maniraptora is, well, a stretch.
Maybe the common ancestor of deinonychosaurs, oviraptorosaurs and
avialans had some aerial locomotory ability - that seems entirely
reasonable. But powered, flapping flight??!!
> Just how big does that sternal keel have to be for one thing?
Dunno. But it would probably help to actually have a sternum in the
first place. So far, there's no evidence that either _Archaeopteryx_
or _Sapeonis_ even had a sternum, never mind a keel.
> As I said, if it looks like a damned boid, it's a damned boid
This reminds me of the prevailing definition of pornography: hard to
define, but you know it when you see it.
> (must be said
> with appropriate Brooklynish/Bugs Bunny accent and attitude). If a person
> saw a flock of Confuciusornis flapping as they almost certainly did over the
> Yixian lakes then they would naturally say "look at those birds!" Ain't
> nothing wrong with that.
I'm not certain that this panorama actually happened. There are other
possible explanations on how so many _Confuciusornis_ ended up dead in
a lake, which I won't go into here.
In the immortal words of Porky Pig.... Th-Th-Th-Th-Th-That's all folks!