[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
There was a lot of mail on this one, but instead of answering each in
turn, I'm going to answer them all at once, right here.
First, the arms of *Deinocheirus* are morphologically similar to both
oviraptorosaurs and ornithomimosaurs. The scapula and coracoid point at
the former, and the rest of the arm, minus the claws, at the later. Of
course, when considering that the two groups are pretty close to each
other anyway, in a sister-clade relationship-like way, not unlike
allosaurs and metriacanthosaurs [sinraptorids].
Yeah, sure the claws are hooked, but oval in cross section as Tom has
pointed out. They're also equal in size, the metacarpals are equal in
size, but the forearm still looks a lot like oviraptorosaurs to be too
close for comfort. Ah well, nothing's easy.
So, we get convergence in this dinosaur, but as to either side, we don't
know, and probably won't until more whopping deinocheir specimens pop
up. As for the type specimen, I've seen a field drawing of the thing,
with short-spined vertebrae and rib fragments, including one
proximal-half rib with nice head. The vertebrae are dorsal and posterior
cervical, but too few to be sure of neck or dorsum length.
On a project with some theropods (allosaurians to be exact) that I'll be
posting soon, I've run into the chance of making proportionate ratios,
and one of these is a humerus-to-neck ratio.
Before I get too far into this, I'll state that yes, there is another
dinosaur with long arms relative to body size that fits the group, and
two more with long arms to body size that don't. The first is
*Oviraptor,* long arms that when walking would have almost dragged on
the ground (I've stated this before on the list, I believe); the other
two are *Xuanhanosaurus* and *Therizinosaurus.* I know next to nothing
on Xuan, but the scythe-clawed one I have more than ample data, and such
a relative comparison includes the oviraptor--therizinosaur theory, in
that humerus to scapula/coracoid is about 1:1.5/1:1.2 while
*Deinocheirus'* is 1:1.1 or therabouts. (Since the therizinosaur's
scapula is incomplete, who knows?) Oh, and there are therizinosaur ribs
known, from *Segnosaurus,* *Alxasaurus,* and *Therizinosaurus* (or
whatever those ones from Uzbekistan are).
Crunching data is good, and working well into the night, I've got lots
of it, mostly repititious junk. (Gotta get organized, one of these days.
. . . ) But anyway, deinocheir proportion humerus to body length ratio
is inconclusive for that tends to morph, so I use scapula to body
length---on an ornithomimoid, we'll say 1:12, or 25.2 feet or 7.7
meters; on an oviraptorosaur, about 1:5.8 or an even half- proportionate
to an ornithomimoid like, say, *Gallimimus*, which will give us an index
of just near 21.5 feet or 6.6 meters. Now, on humerus to femur
proportions, the humerus tends to equal the length of the scapula, so I
can give a generalized length of about 2.01 feet (612 milimeters) for
the scapulocoracoid (my figure may be off) and thereabouts arriving at
620 mm for the femur (and therefore 2.03 feet---not much of a
difference, actually). This gives us apporximate lengths by humerus/body
ratio figures between 1:10 (10.3 ft/3.1 m) and 1:8 (20.7 ft/6.31 m) with
deinocheir at 1:10.5 (27.5 ft/8.3 m).
So, the relative lengths of these dinosaurs remains the same for which
ever ratio I've used, but this is subjective, and I'm using a small pool
here for reference. However, not including the therizinosaur ratio,
which in *Alxasaurus* is the only reliable one, *Deinocheirus* is a
25-27 foot theropod, toothless jaw, long arms and relaively short legs,
chunky chest, long neck, and whatever pops up might as well be true
until a real specimen is found.
It think I've gone way over my two cents worth, here. Oh, and don't
forget to aim your rocket launchers at this, I'll wait.
Jaime A. Headden
Get Your Private, Free Email at http://www.hotmail.com