# Re: Running T. rex

```> Hello all,
>
> A month or two ago I spoke with Mr. Carrano concerning Sue's speed, and
that
> of T. rexes.
>  [snip]
>
> Next we take the stride length of T. rex.  A step covers fifteen feet, so
a
> stride covers thirty.  Now we assume that T. rex could take two steps per
> second, a reasonable estimate.  If so, then T. rex would move 30
> feet/second, which equals 20.45 miles per hour.  This is an acceptable
> walking estimate for the animal.

Wait a minute... once more for continental Europeans... 15 ft are (*tip,
tip*) 4.572 m, so 30 ft are 9.144 m. :-o Oh boy. And 9.144 m/s are *32.9184
km/h*... I doubt I can *run* that fast. I've completely neglected the
effects of sheer size :-[ , and as we all know (since reading PDW),

*************************************************************
SIZE DOES MATTER

Godzilla
*************************************************************

> Mr. Carrano mentioned that, assuming no aerial phase possible, then T. rex
> could speed this up slighty by either increasing the stride or taking more
> steps per second, both of which are very limited.  If T. rex managed to
> cover five more feet per second, by whatever method, this would equate to
24
> miles per hour.  But these calculations of fastest non-aerial-phase speed
> verge on the subjective.

35 ft = 10.668 m, therefore 35 ft/s = 38.4048 km/h.

> I asked about why no aerial phase is likely in this animal.  I also
> mentioned the figures from Gregory S. Paul's _Predatory Dinosaurs of the
> World_ that state T. rex having similar limb structure as
ornithomimosaurs,
> and so bone structure would allow for an aerial phase.  Mr. Carrano told
me
> that not only are the T. rex limbs and ornithomimosaur limbs similar, but
> they are statistically identical to each other.

I've read the book, the figure is *impressive*, but how "statistically"?

> He told me that the
> comparison doesn't help too much though, because both animals are extinct.

Well, "*lol*" is surely an exaggeration, but has anyone ever thought that
ornithomimosaurs couldn't run?

> Another issue he brought up was that in an aerial phase, an animal would
> have to sustain many multiples of its own weight in landing (which I
> question, granted momentum makes the animal accelerate to the ground
faster,
> but many multiples seems too excessive).  This is why the bone structure
> plays the great role it does.  Could T. rex support the weight of a run?
> There is no definitive answer to this.

Not to date, but one could certainly try to compare bone structures. There
have been papers about "bone strength indicators"...

> Next is propulsion.  Could the animal move itself that fast, does it have
> the muscle?

Much more difficult to ascertain, in any case.

> Mr. Carrano cited research by John Hutchinson that shows T. rex
> as not having the adequate muscle mass in its caudofemoralis to propel
> itself into an aerial phase.  Mr. Carrano stated flatly, "So could Sue
run?
> I doubt it, but of course I cannot prove it."

Next question: There were other femur-retracting muscles than the _m.
caudifemoralis longus_, weren't there? Isn't it probable that the
postacetabular blade was the attachment site of one such muscle? (Please
correct me if I'm wrong, my knowledge about muscles is rather minimal.)

> That is about it.  I feel as if I successfully repeated this without my
bias
> for a running T. rex getting too involved.  If this discussion continues,
I
> would like to hear the opinions of more experienced members of this list,
> but I'm assuming this discussion has been had repeatedly, so most people
> will not be interested in continuing it.  If anyone has any views, I too