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Re: Lack of Running Giant Theropod Tracks

>   Unless I missed a major discovery somewhere, we have yet to find a
> trackway that proves that giant theropods could run. What about the
> Paluxy River Acrocanthosaur/allosaurid trackway that is "missing" a
> footprint on one side? It is ulikely that the Acro was hanging onto the
> side of the sauropod, since there is no change in the sauropod's gate,
> and there is no distortion in the "hopping" print as one might expect.
> If the Acrocanthosaur (or similar allosauroid) was "skipping" to keep
> pace, that would mean this huge animal hopped on one foot (both feet
> were in the air at one point). Doesn't this trackway then demonstrate
> that at least this theropod had leg muscles strong enough to propel it
> into an arial phase in its stride and was therefore capable of running?
> How long was the hop length? Couldn't you use the "hop" length to
> calculate the force needed to propel a 4 to 6 tonne animal through the
> air (on one foot) for that distance and then use that data to help
> calculate potential run speed? I'm sorry if this has been brought up
> already. I checked the list and couldn't find much on this subject
> beyond paper requests.
A complication here: the Acrocanthosaurus may not have been hopping so
much as been carried along by the Paluxysaurus/whatever. So it might not
be the theropod's leg muscles alone that lifted it off the ground.

That said, there are a number of reasons to expect large theropod running
tracks to be rare:
* Such big animals may not have run or run much
* &/or they are unlikely to have run on wet, slippery surfaces that can
record a trackway
* &/or the stride length of a fast running large theropod will be so long
that you need a very large surface to record them.