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Re: Martin 2004 critique (somewhat lengthy)
----- Original Message -----
From: "Mickey Mortimer" <Mickey_Mortimer111@msn.com>
To: <dinosaur@usc.edu>
Sent: Sunday, May 15, 2005 12:18 PM
Subject: Martin 2004 critique
"Archaeopteryx lacks basic features of both modern bird and dinosaur
postures: and it is difficult to argue that it shared their peculiar backs
while running, or that the common ancestor of birds and dinosaurs had
already achieved such a running posture. [...]"
Humans and kangaroos (and ground sloths, chalicotheres, derived
segnosaurs...) are almost unique, _not_ normal, among vertebrates in not
holding their backs horizontally. Martin seems to have missed this.
"Embedding birds in the maniraptoran crown group coupled with a Late
Jurassic age for Archaeopteryx creates a similar problem. Not only is
Archaeopteryx older than any credible maniraptoran fossil, but
maniraptoran
diversification must be even older"
I guess the definition of "credible" is the issue here...
Finally, the very studies Martin advocates HAVE been done, by Brochu and
Norell (2001). They concluded deriving birds from any non-dinosaurian
archosaur involved far more temporal inconsistancy and that the fossil
record actually fits BAD rather well compared to other accepted tetrapod
phylogenies.
But why should Martin read the JVP? He isn't interested in dinosaurs*. He's
an ornithologist -- and refuses to understand that he can't make competent
statements about the origin and early evolution of birds without being a
dinosaur expert. I'm sure he doesn't follow the discussion! Feduccia,
likewise, didn't know any of the recent ( = newer than The Dinosauria I)
work on Coelurosauria and seemingly still thought it was the old wastebasket
before I sent him the long list of apomorphies from HP Oliver Rauhut's
dissertation. Hey, in his 1996 book he still preassumed that hadrosaurs were
aquatic and therefore (logically!) concluded the paleontologists must all
have been too stupid to take their increased preservation potential into
account when calculating predator-prey ratios!!! It's just like how most of
us don't follow the apparently ongoing discussion about the monophyly of
"Old World flycatchers"... except for the consequences.
* Except Korean brachiosaurs. He coauthored the description of the first
"brachiosaurid" tooth from South (of course!) Korea a few years ago, as well
as a paper on sauropod tracks from there...
Martin's next section is titled "anatomical barracades". Instead of
bringing
them up again, what Martin really needs to do is address Makovicky and
Dyke
(2001)- Naive falsification and the origin of birds. For all these
barracades are are more instances of naive falsification. Birds and
dinosaurs are supposedly different in some characters, and those states
couldn't possibly have evolved from each other, so they must have a common
ancestor before either trait evolved in each line.
Parsimony with one character. The precladistic way of phylogenetics.
"The teeth in birds or crocodiles are bordered lingually by an extension
of
the tooth-bearing bone (premaxilla; maxilla or dentary), while dinosaur
teeth are bordered by hypertrophied attachment bone (superpleurodonty:
Martin and Stewart, 1999). This suggests that the common ancestor of birds
and dinosaurs did not have socketted(sic) teeth."
"Socketted" is the British spelling.
"... although dromaeosaurs were originally reported to lack interdental
plates, a signature trait of dinosaurian tooth implantation. Their tooth
replacement has also been claimed to be birdlike (Currie, 1987). If they
had, or had had, the avian/crocodilian implantation and replacement
pattern,
we might argue instead that they are not dinosaurs."
Currie's 1987 paper was on Troodon, not dromaeosaurs.
Long live Deinonychosauria in the original sense of 1967.
Martin brings up digital homology, assuming digital identity and analgen
identity are equivalent, without even a mention of frameshifts.
Oh, frameshifts aren't needed. Even Feduccia's own photos of ostrich embryo
hands show a little unchondrified spike in some stages that is in the right
position for the 5th finger -- lateral to the 4th finger which Feduccia
labels as the 5th.
Martin then goes on about the astragalar ascending process and pretibial
bone, spending quite a lot of time trying to show Archaeopteryx had a
pretibial bone. He ignores Shenzhouraptor (= Jeholornis), which clearly
shows an ascending process (that was noted and illustrated by the authors
to
help prove BAD), despite having referenced the taxon only two pages prior.
Rahonavis would also help here, though one must wonder if Martin thinks
it's
a maniraptoran or a sauriurine, or both. He says, "We can speculate the
common ancestor of birds and dinosaurs lacked an ascending process of the
ankle, and that bipedality was achieved independantly." Um, what about the
ascending processes of non-avian maniraptorans? Don't they throw a wrench
into Martin's hypothesis?
And what about the supposed pretibial bone of *Dilophosaurus*, which could
indicate the ascending process is _always_ a separate entity that fuses to
the astragalus (or calcaneum)?
The short postacetabular process of birds is said to be more primitive
than
dinosaurs, which was "already elongated in the coelurosaurian dinosaur
Coelophysis from the Triassic." Coelurosaurian Coelophysis? Martin sure is
up to date on dinosaurs...
See above.
Perhaps Martin thinks that postacetabular processes
can only grow, and not shrink, but how he could
defend such a view is beyond me.
Here again he keeps playing parsimony with one character.
Finally, Martin thinks the apparently absent external mandibular fenestra
of
Archaeopteryx is symplesiomorphic with pre-archosaurian reptiles, thus
providing more evidence birds are outside the crocodile-dinosaur clade.
The
presence of mandibular fenestrae in oviraptorosaurs and deinonychosaurs is
said to be convergent with dinosaurs+crocs. Jixiangornis, Omnivoropteryx,
confuciusornithids, Vescornis and the Spanish enantiornithine nestling all
have mandibular fenestrae too. Thus the distribution is not so simple, and
cannot be used to place birds so basally. Of course, even if birds
universally lacked mandibular fenestrae, their absence in compsognathids
proves the state can evolve from one where fenestrae are present.
Parsimony with one character, coupled with the usual amount of ignorance.
It's nice to see Martin agreeing with current phylogenetic thinking that
avicephalans and Cosesaurus are outside the Crocodylia+Dinosauria clade.
Oh yes...
Finally, Martin uses the elongated postacetabular process as a character
to
unite ornithischians and Coelophysis, but this character is not present in
basal saurischians (Eoraptor, herrerasaurids) or sauropodomorphs.
How convenient they are all absent from the phylogram.
The long primaries of Caudipteryx are said to "so greatly reduce the
usefulness of the hand for grasping that it must imply derivation from an
arboreal flyer/glider." Someone hasn't read Gishlick (2001) I see.
Of course not. It's a thick, expensive, heavy book purely about dinosaurs.
Why on the planet should he.
There are a lot of unsupported assumptions about microraptorians. The
hindwings were "clearly a gliding adaptation". "In order for the femur to
function, they must be able to extend laterally." The "animal could barely
walk, let alone run."
Of course not -- if you disarticulate its hip joints or (as in the fossil)
fold the ventral halves of the ilia into a horizontal position and rip the
pubes and ischia off.
This is also supposedly supported by the small toes
and reversed hallux. I doubt the toes are any more reduced than
ornithomimosaurs and troodontids, and the hallux is not reversed.
Besides, climbers need _longer_ toes.
Martin now correctly believes Longisquama
lacks a mandibular fenestra, and says it has thecodont dentition,
including
teeth with constricted bases. Other avian characters are listed, but are
of
course, also found in non-maniraptoran theropods- [...] furcula
(theropods)
Of course he doesn't even mention the possibility that this bone could be an
interclavicle instead.
Martin's Triassic bird Protoavis
has more quill knobs on its third metacarpal than its second, so might
suggest basal birds developed primaries on the outer edges.
These are just features of squishing, as the photos (Ostrom Symposium
volume) show.
Also, because maniraptorans had arched non-pronated hands,
their 'outer edge' IS metacarpal II.
Difficult to grasp if one doesn't read Gishlick (2001).
Figure 4 includes terribly inaccurate reconstructions of Longisquama's
skull
and furcula. The furcula looks like it was just altered from Archaeopteryx
or Bambiraptor, instead of the more U-shaped structure in Longisquama with
its pointed distal tips.
Pointed tips? Sounds like an interclavicle...
Martin's conclusion has much praise for Paul's work, but misrepresents it
as
being equivalent to his own.
As predicted in DA!!!
Another interesting fact- "The monophyly of the Dinosauria has always been
difficult to support." Apparently Martin hasn't read any of the relevent
literature since the mid 1980's.
Of course not.
He then says Confuciusornis may be related to
oviraptorosaurs, while Jeholornis "seems closer to dromaeosaurs". So one
is
left confused as to exactly how Martin thinks maniraptorans relate to
birds.
I think he doesn't. Perhaps he still lives in the era of the blob trees,
where blobs become broader, give rise to other blobs, become narrower and
fade out... -- in other words, perhaps he hasn't wasted any thought on such
details, and hasn't got the idea that he could. Tree-thinking is young.
Are maniraptorans sister to Ornithurae+Sauriurae, sister to other
Sauriurae,
polyphyletic within Sauriurae? He supports each of these hypotheses
somewhere in this paper.
Perhaps you should think of Maniraptora as an undivided blob that gives
rise -- near its upper tip -- to Sauriurae on the left side and Ornithurae
on the right side. Or perhaps Maniraptora is the lower half and Sauriurae
the upper half of a blob that gives rise to Ornithurae somewhere around the
middle (the broadest part).
One has to wonder if Martin has thought through the consequences of
embracing Protoavis as a bird (the following comments assume Chatterjee's
identifications are correct). The acetabulum is completely open and the
femoral head medially projected, which would not be expected in a Triassic
bird if Archaeopteryx's supposed "somewhat sprawling posture" is
primitive.
It also has an astragalar ascending process, large postacetabular process
and external mandibular fenestra. This would support these as
symplesiomorphies of birds, contra Martin's hypothesis. [big snip]
Too many characters. Parsimony is done with one character at once. It's
still 30 years to the invention of the 366 MHz processor.
And there's still no book entitled "What you always wanted to know about
cladistics but never dared to ask".
So Protoavis either helps the temporal paradox but disproves most of
Martin'
s proofs that birds branched off prior to theropods; or it makes the
temporal paradox worse by requiring ghost lineages of 65 Ma for
sauriurines
and 80 Ma for ornithurines, and makes Martin's phylogeny less credible by
either having dinosaurian/maniraptoran characters in a basal ornithurine
or
ornithurine characters in a maniraptoran.
Hey cool. :-)