# Re: Acrocanthosaurus trackways, one last thing...

```I suspect that the following questions were addressed to me, so here
goes:

>>> dexter dexter <dexter1647@caramail.com> 04/03/02 07:35PM >>>

One last thing concerning the _Acrocanthosaurus_ trackways :

While there was mention of the three fastest animals of the lot, I
don't remember for
the biggest of those three ; One is said to have a footprint lenght of
29 cm and a
stride lenght of 566 cm ; Estimated moving 12.1 m/sec-1 (43.5 km/h).
There is no
mention of the second one (Estimated 8 m/sec-1 / 29 km/h), but what
third one ? I know the footprint lenght is 38 cm, and is estimated at
moving 12 m/sec-1,
but what's the stride lenght of this specimen ? (By stride ; One stride
includes two steps..)

Well, I could interject the justly famous Holtzian comment here: Read
the paper, &%\$#@.  It was published as J.O. Farlow (1981, Nature 294:
747-748).  Mean print lengths and stride lengths of all of the trackways
are duly reported therein.  There is also a photo of one of the
trackways presumably made by a running dinosaur.

For the three dinosaurs thought to have been running, the mean
footprint lengths (FL) and stride lengths (SL) are as follows:

FL = 38 cm for a SL = 658.9 cm
FL = 37 cm for a SL = 538.5 cm
FL = 29 cm for a SL = 565.6 cm

J.Farlow mentionned that it could have been a subadult specimen of _A.
atokensis_, but
how can we scale from that ? I've heard you could estimate the hip
height and the weight
of the trackmaker ; if true, does anyone have the stride lenght &
estimated hip height/weight
of the specimen ?

Not exactly.  Based on complete skeletons, one can roughly estimate the
hip height that would correspond to the length of the footprint.  See
Tony Thulborn's (1990, _Dinosaur Tracks_).  A relationship between
footprint size and dinosaur mass hasn't been worked out, but in
principle a regression of mass on footprint length or area could be
created.  Problem there is that nonavian dinosaurs are a tad extinct,
making all body masses for said beasts hypotheses in their own right.

At last, I'm not sure I understand for the "footprint", he may have
taken some pictures.

You bet!  Oodles of photos, and several casts as well.

Is
the footprint including whole phalanges & metatarsal/phalange joint, or
is it simply only a
part of the phalanges being held on the ground while running ?

Yes on all counts, but it depends on the digit.  Digit IV seems to have
impressed over the entire length of the digit plus the
metatarsophalangeal joint; digits II and III didn't register over their
entire lengths.  For details, see Farlow et al. (2000, Theropod
locomotion, in _American Zoologist_).

Thanks,
Tom Miller
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