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Re: Oryctos Is Back
> All of these questions are currently best answered by
> "Good question! Next
> question?" -- except one: Neornithes and
> Enantiornithes are clearly much
> closer to each other than to Archie. Supporting evidence
> can be found in the
> shortened tail and pygostyle, the reduced 3rd finger, the
> flange on the 2nd
> finger for firmer wing feather attachment, the alula, the
> the joint between scapula and coracoid, and numerous other
> AFAIK mostly
> flight-related characters
I would not bet on half of the traits. Maybe they're good, but I would not bet
on them. For now.
3rd finger and carpometacarpus seem too good to be wrong. The rest...
> Contradictory evidence (keywords: Saururae,
Bah! as if we had the means to even remotely understand it when these theories
were born. Sometimes the occaisonal forgotten gem surfaces, like the paper
written nearly 100 years ago, by one of the first scientists who studied
Przewalskii's Finch, and noted that it was something completely different from
all other passeroids.
He was right.
But that here is not it. It has been chewed through and through. Like with
_Longisquama_ (why oh why _Longisquama_?)
> *Sapeornis* is fairly clearly the sister-group of the
> misnamed Pygostylia
> (see the simplified tree below for where that name
> applies), but it has
> evidently undergone its own specialization, leading to a
> couple of
> convergences with Ornithothoraces.
Indeed. And that is making me suspicious. We have an assemblage of taxa from 2
regions distant in space and hardly distant enough in time to show that at
least 2 lineages of animals were to be found on Earth ~140 mya that were
birdlike enough to become actual "birds" with just one or two minor changes -
teeth, tail, arms, fingers. Volant enough that anything improving aerodynamics
was a HUGE benefit.
The differences between enantis and euornis [thx] are peculiar - them having
evolved from closely related *non-volant* (maybe fluttering) mid-late Jurassic
ancestors would make sense of that. Take the scapulacoracoid: with the right
genes present, it just needs to happen - and bone fusions are not that
uncommon, only they're ofter prenatally lethal. Not this time apparently. So
with the right genetic framework and the right kind of anatomy and lifestyle,
and feathers of course, you're rather liable to get a scapulacoracoid sooner or
"The right genetic framework" is to be found in many relatives of one species
in which this is possible, i.e. it is widespread among a clade. The fact that
the fusion, as far as it seems, was ontogenetically *very* different, but only
insofar that a *slightly* different kind of "elongate til hitting similar
tissue, fuse" program was realized.
Similarly, when you code pygostyles as binary character, you will get weirder
results today than two weeks ago, so... it's a bit of a cnemial crest thing.
The remiges flange (what's the name?) is something mandatory for a lineage to
be fully flight-capable. You can only achieve so much with flight feathers
latched to fingers, no matter how stubby they are.
The general picture is that of a time in theropod evolution when certain
hereditary developmental disorders became highly advantageous.
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