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RE: Lack of Running Giant Theropod Tracks



> 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.
 
 
  If that were the case, it seems like the angle of the hopping print would 
have changed quite a bit since the Acro would have been hanging off the side of 
the sauropod while moving forward. Sauropods lacked a big convenient "butt" to 
latch on to, which would have left a swinging tail, a moving leg, or the flanks 
as gripping points. Considering this, I would guess the Acrocanthosaur would 
have left an extremely distorted foot print or two if it was carried along by 
the sauropod. I also don't understand why there wouldn't be any tail drag marks 
from the Acrocanthosaur considering the angle it would have been in while 
hanging from the sauropod's side. The more I think about it, the more 
improbable that explanation seems. 
 
  Many animals (including humans) make skip steps while walking or running for 
various reasons. I, as a plantigrade primate, can do this while walking on the 
balls of my feet in a smooth fashion with no loss of balance or drop of my 
heel, so I wouldn't be surprised at all if theropods were capable of doing the 
same. 
 
Simeon Koning     
 
 


----------------------------------------
> Date: Fri, 26 Nov 2010 19:57:29 -0500
> From: tholtz@geol.umd.edu
> To: simkoning@msn.com
> CC: dinosaur@usc.edu
> Subject: 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.
>
>
>