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Re: thanks for tracks & a question

Hello Dwight, Jack, and List,

    It has been several days, Dwight, since you asked another good question
about what might be determined from study of dinosaur trackways.  So, for
those who may have forgotten the question, I'll repeat it:

-----Original Message-----
From: Stewart, Dwight <Dwight.Stewart@VLSI.com>
To: 'STARSONG@prodigy.net' <STARSONG@prodigy.net>; jconrad@lib.drury.edu
<jconrad@lib.drury.edu>; Dino mailing list <dinosaur@usc.edu>
Date: Tuesday, February 23, 1999 10:46 PM
Subject: RE: thanks for tracks & a question

   "Okay, this brought a question to mind that was rattling around in
my head a few weeks ago.  To whit: can anything
be inferred about dinosaur mass/weight from the prints, aside from
the "wide/narrow" gauge artifact you just mentioned?
Here, I was thinking of forensic work as the model, in that the
approx. height & weight of a human can be derived from
shoe size, stride length, & the depth of the tracks.  Now, I realize
that preservation conditions would greatly complicate
this, as would the question of under track, over track, etc.  But,
nevertheless, it seems intuitively feasible."

    Yes, forensic work does provide a good model of ways to derive a maximum
amount of data especially from trackways, but even from singular tracks, in
some instances.  Of course, as you mention, the derivations will be more
accurate when one is working from prime tracks, rather than under-prints,
over-prints, etc.

    A good reference on matters related to this is a small but very useful
McNeill Alexander, and published by Columbia University Press in 1989 (ISBN

    Yes, 'ball-park figures' for an animal's velocity (or lack of it) can be
derived from trackway (or track) studies.  Of course, trackways are best for
this, but singular tracks can reveal certain limited data.  In the latter
case, for example, I have found several Theropod tracks (various types and
sizes) in which an animal was making a very fast change of direction.  One
can easily determine by observation, the degree to which the foot was tilted
(relative to the horizontal layering of the sedimentary substrate) during
the turn, the amount of substrate that is pushed up by the centrifugal force
involved at the moment of turn.  Then, from these observations and other
data (and calculations) one can come up with reasonably reliable figures for
substrate penetrability and compactibility at the time of the event, the
animal's approximate mass, and probable velocity, etc.

    Two of the things that have surprised me about some of the Theropods
from Maryland's Early Cretaceous is that apparent speed and agility.  Then,
there are the several tracks possibly made by Dromeosaurs  with that
second-digit's 'terrible claw'!  I had never thought about the tip of this
claw being so knife-blade thin and awesomely sharp (probably because I'd
been thinking mainly in terms of the claw bones we see, instead of the much
longer, sharper keratinous sheath that surrounded it in life), but a couple
of the tracks I've found here leave no doubt in my mind that this particular
Theropod was truly a 'Jack the Ripper'.

    There are a few tracks with substantial amounts of 'splash-out' ,
suggesting a surprisingly high-speed run in very wet soil that was not --
all the same -- covered with water (or the splash drops would not look as
they do).

    I hope this provides some insight, and I shall forgo quoting any of the
formulae Alexander provides in the book mentioned (or any of the others
available in various publications).

    Some work has already been done to extrapolate quantitative data from
trackways, but it seems to me that this is a fairly new field of endeavor,
with much more potential than what has yet been realized, especially if one
uses sophisticated computer software designed for modeling the action and
its effects. I'm not as yet aware of any off-the-shelf software specifically
designed for this kind of work, but I suspect there are some extant
software that could help in (or be modified for) this type investigation.

    One area in which I use computer technology to study tracks (and the
few small trackways available to me) is via IMAGE PROCESSING.  Enhancement
sometimes reveals meaningful details that had not been noticed before.  It
also has enabled less-experienced observers to readily perceive details of,
and hence to interpret the tracks with more insight.  So far as I know, I am
the first track researcher to utilize this helpful innovation in study of
mesozoic tracks.

    Relevant to this: Several summers past, I had time to do some dinosaur
tracking in Texas, where I found something so surprising and exciting that I
slept very little for a couple of weeks after the discovery :  The short trackway of a
HATCHLING Sauropod from the Comanchean (Lower Cretaceous) of Travis County,
consisting of three clear imprints and a fourth (right manus) that is less
clear and possibly distorted by the right pes (back foot) coming down too
close behind that right front foot.  In other words, there are two superb
(shallow but beautifully detailed) left and right pes (back foot) imprints,
and one equally superb, right-manus imprint, along with the much-less clear right
manus (front foot) impression.

    Dimensions?  Well, each of the two pes impressions is only 5.8 cm in
length, while the manus measures only 3.0 cm in width!  These beautiful
little tracks are recorded in a carbonate (marine lagoon) substrate, and are the
first hatchling sauropod tracks documented anywhere.  If we take the typical
Paluxy Sauropod pes length to be 85 cm long, then at 5.8 cm, the Travis
county hatchling pes is only 1/14.6th of that size!

    Image enhancement of a photo of this track-bearing slab made the tiny
Sauropod tracks show up ever more marvelously, revealing some details that had
not been noticed before enhancement.

    Those tiny Sauropod tracks are virtually identical in form (but not in
size, of course) to the best of the Paluxy river-bed tracks of Texas, except
that the four sharp claw marks on each pes imprint (the 5th toe seems
represented only by a bulge of the foot flesh positioned externo-laterally
to toe 4) seem to have been made by claws even shaper and, relatively,
longer than corresponding claws in imprints made by the more-adult Texas
sauropods.  Dr. Robert Weems of the U.S. Geological Survey, Reston,
Virginia, has speculated that long, sharp claws on the hatchling Sauropod
may have been useful in escaping from the egg shell when hatching time came,
and that the claw sharpness probably diminished as the hatchling walked more
and more in silt, sand, or across pebbles, thus the sharpness of these claws
suggest that this particular track maker was very recently hatched.

    Some skeptics out there who have not had the chance to see these tracks,
might wonder whether, knowing the shapes of the Larger Texas Sauropod
tracks, some of us might have just imagined that random forms in the
carbonate substrate look like the Paluxy Sauropod tracks.  Well, seeing them
would take care of that; but since I cannot include illustrations or photos
in postings to this list, I shall mention one other nice advantage of
computerized image processing:  Using absolutely none of the artwork
capabilities of the computer, but using a series of commands that are
computational, only, I had my system look for and draw the outlines of
whatever forms it detected on the slab.  Really, to my astonishment, it drew
ever far better outlines of the Paluxy-like hatchling tracks than I had even
imagined (in my wildest hopes) it would do!  My point?  My computer was not
fantasizing Brontopodus birdi type tracks, as a sight-unseen skeptic might
speculate those of us here had done.

    Excellent images of many of the small to medium-sized tracks can be
obtained by simply scanning them on my flat-bed scanner, which has a very
surprising depth of field.  This provides a quick and easy way of cataloging
the collection with high quality color photos that include size-reference

    That's it for now.

    Ray Stanford