Re: Deinocheirus

["Jaime Headden" <jaemei@hotmail.com>]

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

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