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Estimating Hip Heights
Senter, P & Robins, H. J. 2010. Hip heights of the gigantic theropod dinosaurs
*Deinocheirus mirificus* and *Therizinosaurus cheloniformis,* and implications
for museum mounting and paleoecology. _Bulletin of th Gunma museum of Natural
Â available online at:
Â "The gigantic theropod dinosaurs *Deinocheirus mirificus* and
*Therizinosaurus cheloniformis,* from the Upper Cretaceous Nemegt Formation of
Mongolia, are known only from bones of the forelimb and pectoral girdle. They
possess the longest known forelimbs among theropods. To determine whether the
lengths of forelimb elements have predictive value for the length of the
hindlimbïHL = length of femur + tibia + metatarsal IIIï, we computed Spearmanâs
Rank Correlation Coefficients for HL versus various forelimb bones in
ornithomimosaurs, theropods in general, and bipedal dinosaurs in general. We
found that scapular length and humeral length correlate welïl> 90%ï with HL in
all three samples, but lengths of the radius and second metacarpal do not.
Using regressions of scapular length Ã HL and humeral length Ã HL we find that
HL is 3323.14 - 3646.50 mm for *D. mirificus* and 3001.10 for *T.
cheloniformis.* These two animals have the highest HL in the dinosaur fauna of
the Nemegt Formation, and *D. mirificus* has the highest HL of any theropod.
Contemporaneous tyrannosaurids could bite no higher than their bellies and
thighs, and other contemporaneous predators were too small to have preyed upon
them. If *D. mirificus* and *T. cheloniformis* were browsers and
contemporaneous herbivores cropped vegetation with the neck in the
osteologically neutral position, these two theropods would have competed for
foliage only with each other."
Â Comparatively, *Deinocheirus* was as tall at the hip as was *Tyrannosaurus
rex*, while *Therizinosaurus* was shorter. Among theropods, they are they
tallest (at the hip). As some have shown, including Paul, the posture for
*Therizinosaurus* would have likely inclined the body upwards at the hip at it
seems to have done for *Nanshiungosaurus* (the next biggest therizinosauroid),
and this would have made *Therizinosaurusd* the tallest theropod on record.
*Deinocheirus* is a little trickier: ribs are known for *Deinocheirus*
(Osmolska and Roniewicz, 1970), but they are poorly distinguished from the
pectoral girdle and forelimb; it has also been questioned that *Deinocheirus*
is an ornithomimosaur, which makes comparing regressions a little harder
directly, but fortunately Senter and Robins avoided this by using a mean of
theropods rather than just ornithomimosaurs.
Jaime A. Headden
The Bite Stuff (site v2)
"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion
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