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Ivan Kwan <firstname.lastname@example.org> wrote:
Or what if others find that once & for all, that dromaeosaurs (or
troodonts or oviraptorosaurs) actually evolved after Archaeopteryx split
off the maniraptor lineage?
I'd recommend reading the works of a fellow named Gregory S. Paul, who
explores the exact same issue that you raise. _Dinosaurs of the Air_ is his
latest volume, in which he argues (quite forcefully) that dromaeosaurs (and
troodonts and oviraptorosaurs) are indeed secondarily flightless, and
branched off the maniraptor line *after* _Archaeopteryx_. I'm not sure I
agree with all of his interpretations (though I'm sorely tempted), but it is
nevertheless an illuminating read - and wonderfully illustrated.
Would that put the dinosaur-bird debate in a whole new perspective?
No. The relative position of dromaeosaurids and _Archaeopteryx_ in theropod
phylogeny is less important than the bigger question did birds evolve from
theropod dinosaurs. The evidence points to a resounding "Yes".
I think we need people to scrutinise every feature of _Archaeopteryx_ from
every angle, to note every detail, and compare it with EVERY (and i mean
every) other Mesozoic bird species & non-avian maniraptor.
Some folks are endeavoring to do that very thing. I'm sure their Frequent
Flier programs are benefiting as a result.
I believe the disagreements on coelurosaur & avialan phylogeny will be
around for quite a while, & I do hope that things get resolved as quickly
as possible, but I just wish we had more specimens of _Archaeopteryx_ to
give more solid proof that it is the "First" bird.
I'm not sure *more* specimens will help all that much. They may be
preserved in 2-D "steam-rollered" fashion, but as 2-D specimens, go they are
wonderfully preserved. A *lot* of info can be pulled from the specimens,
individually and combined. What we need is the direct ancestor of
_Archaeopteryx_, and maybe the direct ancestor of that species, and maybe
the direct ancestor of that species. Unfortunately, as in all things, we
have to make do with what we have got. (If wishes were horses...)
By the way, chronologically, _Archaeopteryx_ is the "first bird". It's Late
Jurassic age antedates all other incontrovertible bird fossils (which rules
out _Protoavis_). Phylogenetically, _Archaeopteryx_ is defined as the
basalmost member of the Aves (or Avialae, depending on whose system you're
using.) This is separate from the semantic definition of "bird", which is a
little more subjective. At the moment though, very few people dispute
Archie's title as the earliest known bird.
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