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RE: thanks for tracks & a question




        -----Original Message-----
        From:   RAY D STANFORD [SMTP:STARSONG@prodigy.net]
        Sent:   Saturday, February 27, 1999 1:26 PM
        To:     Stewart, Dwight; jconrad@lib.drury.edu; Dino mailing list
        Subject:        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:
        
        
           "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
        little book entitled, DYNAMICS OF DINOSAURS & OTHER EXTINCT GIANTS
by R.
        McNeill Alexander, and published by Columbia University Press in
1989 (ISBN
        0-231-06667-8).
        
            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'.
        @@@@@@@@@@@@@@@@
        Thanks, Ray.  I figured that HAD to be the case.  The track evidence
for speed 
        & maneuverability certainly seems to imply active hunting behavior.
BTW: were
        there tracks from more than one Dromeosaur at the same site?  What
I'm getting
        at here is evidence of pack hunting.
        @@@@@@@@@@@@@

            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).
        @@@@@@@@@@@@

        Those conditions would logically dictate lower than maximum speeds,
which at least 
        leaves open the theoretical possibility of much faster speeds on
more solid ground,
        right?  
        @@@@@@@@@@@@@@@

            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.
        @@@@@@@@@@@@@@

        AH, Travis County; where my son lives; about 75 miles north of us.
My understanding is
        that the Mesozoic fossil record is better in Travis than Bexar
County (where I live).
        Since it was from the Comanchean, was this sauropod a Titanosaur?
        @@@@@@@@@@@@@@@

            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
        objects.
        
            That's it for now.
        
            Ray Stanford
        
        @@@@@@@@@@@@

        Again, thanks Ray.  

        Cheers;
        Dwight