Re: Archaeopteryx not the first bird, is the earliest known (powered) flying dinosaur

[dinoboygraphics@aol.com]

I would be careful about using the Thermopolis specimen as evidence for 
a splaying posture;  Aside from the cogent points raised by Tim 
Williams, the hips of the Thermopolis specimen are completely broken.  
In fact, Jehol deinonychosaurs with "splayed" limbs invariably either 
have busted hips or exhibit strongl disarticulation.  If one were so 
inclined, you could make a very strong statistical case that apparent 
splaying of limbs varies inversely with fully preserved and articulated 
pelvic and limb material.  Of course we can't always infer causation 
from correlation, but either way the Thermopolis specimen makes a very 
bad case for sprawling limbs.

Also, the microraptor specimens described by Hwang et al (2002) in AMNH 
Novitates very clearly show a normal, cylindrical femoral head.  One 
disarticulated femur is preserved in anterior view, and shows this 
irrefutably.  Claims that Jehol theropods had anything different need 
to a) explain those specimens, and b) show the supposed rounded head in 
a specimen that isn't preserved in an oblique aspect, since in 2D 
fossils like these oblique crushing allows the medial head to be 
squished up into a position that looks rounded when it isn't.

Scott Hartman
Science Director
Wyoming Dinosaur Center
110 Carter Ranch Rd.
Thermopolis, WY 82443
(408) 483-9284

www.skeletaldrawing.com

-----Original Message-----
From: GSP1954@aol.com
To: dinosaur@usc.edu; xingxu@vip.sina.com; elzanowski@biol.uni.wroc.pl; 
evan_hadingham@wgbh.org; frontlinefilm@earthlink.net
Sent: Sat, 03 Dec 2005 11:36:16 -0500 (EST)
Subject: Archaeopteryx not the first bird, is the earliest known 
(powered) flying dinosaur

Even though I still have issues with cladistics, it is nice to see a 
major
cladistic study finally show a large body of sickle clawed dinosaurs 
closer to
the rest of Aves than Archaeopteryx as per the Mayr et al Science paper 
(even
though a host of characters that further reinforce this conclusion were 
not
included). Kind of reminds me of that noncomputational cladogram 
showing
secondarily flightless deinonychosaurs closer to birds than 
Archaeopteryx that
was
published back in 84. One particular point I find quirky is Microraptor 
being
markedly closer to Confuciusornis than Sinornithosaurus, when I have 
found it
difficult to see what in the Jehol dromaeosaurs separates them at the 
genus
level, the separation of these taxa above the species probably 
represents
problems
with accurately determining the characters.

I also like that I'm hard pressed to see where I need to correct the
Archaeopteryx skull restoration in DA, except for making the palatine 
more
dinosaurian
by making it tetraradiate. It is notable that the postorbital process 
of the
jugal, contrary to studies that have claimed that it is located too
posteriorly to articulate with the postorbital, points straight at the
postorbital in
the new skull. This is because the quadrate is strongly procumbent in 
this and
all articulated skulls as noted in DA. Of course a complete postorbital 
is
again not preserved and may have been absent, but other lateral 
temporal skull
elements are  missing in this and other specimens so there is no way to 
be sure.

At this point there is little reason to doubt that the skull of 
Archaeopteryx
is highly or entirely theropodian, including the articulation between 
the
quadrate and pterygoid (there being no solid evidence for a push-pull
articulation
and much against it).

The Thermopolis specimen also verifies that Archaeopteryx lacked all 
the
derived flight adaptations seen in sinornithosaurs (including 
microraptors) -
large ossified sternal plates, ossified sternal ribs and uncinate 
processes, a
strongly bowed metacarpal III (to better spread the primaries), a 
flattened
finger II base that better supported primaries that were more elongated 
relative
to
the hand, ossified tendons on tail. The tendency of some to suggest 
some of
these features will someday be revealed when a fully adult Archeopteryx 
is
found is an ever longer stretch and should be considered moot unless 
such a
specimen actually shows up. As far as I can tell archaeopterygians have 
no
derived
flight features not found in flying dromaeosuars. I have not checked in 
detail
but I do not think these characters are being incorporated into 
cladograms.
Their proper inclusion will only reinforce the more derived 
phylogenetic status
of dromaeosaurs. Would be nice if someone would incorporate these 
features
into their cladistic character lists - I'm not going to do it.

At this point it is hard to see what would make Archaeopteryx more 
avian than
other deinonychosaurs. There are the birdy teeth, but teeth are very 
plastic
in evolutionary terms. Dromaeosaurs even lack the pterygoid process of 
the
pterygoid still present in Archaeopteryx, which still has the old 
fashioned
overlapping cervical ribs absent in the former. Maybe Archaeopteryx 
lacked the
postorbital bar, but as far as I know it has not yet been found in any 
Jehol
dromaeosaurs either, and some birds have it.

My Archaeopteryx restorations dating back to the 80s were so 
dromaeosaur-like
not, as some have sugggested, because I thought they were that way, but
because the osteology shows that they were.

The new specimens, combined with the analysis of the last couple of 
decades,
plus the latest dromaeosaur and troodont specimens, make it clear that 
the
basal deinonychosaur Archaeopteryx is not really the first bird. 
Instead it is
one among many deinonychosaur dinosaurs that had well developed wings.
Archaeopteryx is fast losing its status as the all important "urvogel" 
taxon
around
which centers our understanding of bird origins, which is logical since 
our data

base is dramatically expanding. Archaeopteryx still stands as the first 
and
most basal known flying dinosaur/member of the avian clade, but that is 
an
accident of discovery that will change at some point. The vernacular 
term bird
should probably be limited to avians that look like modern birds, 
particularly
in
having a very short bony tail (and that share the short tail with 
modern
birds, so if oviraptorosaurs developed short tails independently they 
are not
birds, if they inherited their tails from short tailed basal birds they 
too are
birds), unless the bird revolved a long tail (not sure where this 
leaves
Jeholornis).

Basal dromaeosaurs were not only anatomically more derived than the 
earlier
archaeopterygians, they were more derived fliers too. I hope this 
causes
researchers to back off the recent tendency to restore the biplane 
dromaeosaurs
as
primitive protogliders simply because they had been plotting more basal 
than
Archaeopteryx on cladograms. There is no reason to not conclude that 
flying
dromaeosaurs were more advanced fliers than Archaeopteryx. As for the 
latter, as
I
explain in DA it is much too well adapted for flight in having a well
developed wing with large muscle attachments and greater bone strength 
than the
legs
to be adapted for simple gliding. All you need for that is a means to 
stretch
out some sort of airfoil. Some form of powered flight, however crude 
and
limited, was very likely to have been present in archaeopterygians. 
Because
winged
dromaeosaurs have even better muscle attachments, more chest and arm 
strength,
and bigger more firmly attached primaries, they must have been even 
better
powered fliers. To argue otherwise does not sense make. In fact 
sinornithosaurs
were getting close to confuciusornithids in this regard.

Also severly damaged is the hypothesis that the flight features present 
in
flightless deinonychosaurs and other derived theropods are 
preadaptations for
flight. The arguments for folding arms, big sternal plates, pterosaur 
like tails

and so forth having evolved for nonflight purposes and then being 
utilized
for flight were always driven by cladistics rather than functional 
logic and are

now obsolete unless we find Jurassic theropods that clearly evolved 
these
things before flight appeared.

It is now less likely that dromaeosaurs evolved flight independently as
suggested by Makovicky et al. in their Nature Buitreraptor paper. But 
let's not
get
cladistically rigid in reverse. Maybe dromaeosaurs did independently 
evolve
flight, and did so just once, or numerous times. Maybe they lost flight
numerous times, or just once. Same with troodonts and so forth. Maybe
archaeopterygians evolved flight independently. Maybe assorted 
deinonychosaurs
evolved
flight, lost it, evolved it again, and lost it again. Maybe basal 
dromaeosaurs
evolved tandem wings independently. Or maybe this was a stage of flight 
that all

Aves stem from. Maybe the young of the flightless dromaeosaurs had 
longer arms
with wing and could fly, much as ora young often climb while the adults 
don't.
As I noted in DA we have hardly any idea what these things were doing. 
One
thing we do know is that the notion that flight evolved in a simple 
linear
progression from the "Protoavis" to perigrine falcons has been 
demolished. All
sorts
of evolutionary experiments and reversals were probably going on. 
Although
the possibility that flight was never lost in the bird-like dinosaurs 
is not
entirely impossible, it is so improbable that it should be considered
implausible
unless convincing evidence to the contrary developes. In fact we can 
safely
assume that flight was lost numerous times in deinonychosaurs, and 
probably
other bird-like theropods as well. Although evolving flight may have 
been easier

than is often thought, losing it is easier still.

The Thermopolis specimen also shows something important about limb 
posture.
Like all the other complete Archaeopteryx specimens, it is preserved on 
its
side, flattened laterally. One leg is also in normal pose in that it 
projects
ventrally from the hip, the other leg is clearly disarticulated 
dorsally. This
consistent pattern is compatible with the cylinderical hip socket of
Archaeopteryx which did not allow the legs to splay out strongly. Some 
of the
Jehol
dromaeosaurs are also preserved on their sides showing they could adopt 
an erect

leg posture, but many if not most are preserved dorso-ventrally crushed 
with the

legs splayed out to the sides. I have not seen a Jehol dromaeosaur with 
a
truly cylinderical femoral head like those seen in the flightless
velociraptorines, they are always somewhat more rounded in shape. This 
indicates
that the
winged dromaeosaurs could splay their legs out much more than normal in
theropods, although not necessarily entirely flat. This makes sense 
since they
had leg
wings. I find attempts to explain how these hindwings were deployed 
without
sprawling the legs highly dubious.

G Paul