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Sauropod Walking and Swimming



    My comments will follow the quote:

[From: Jeff Poling <jpoling@dinosauria.com>
Date: Tuesday, July 14, 1998 10:42 AM
Subject: Re: Sauropod drinking]


>Betty Cunningham wrote:
>>Was it perhaps water pressure on the internal organs at that depth that
>>helped eliminate sauropods from water?.
>
>   That, and the fact that sauropod feet are designed for a terrestrial
>existence.  It would be very easy for a sauropod to sink in any kind of
>wet, pliant material such as sand or mud.

    (1) The fact is that most (if not all) sauropod tracks published to date
were made
in the very environment you suggest might have been difficult for walking:
lake shores, marine lagoons, flood plains, alluvial sediments, and similar
environments
with pliant sand or mud, etc.  This by no means should be taken to indicate
that sauropods spent the major part of their lives in this environment.

     The famous Paluxy River tracks in Texas were made in a nicely pliant
carbonate sediment.   Also, although the sauropod tracks that I find here in
Maryland range greatly in the size of individual track makers,  the majority
of them  were made in wet, soggy ground.   These animals, whether large or
small, clearly did not avoid such environs.

     (2) To my perception [Note the caution here.], the sauropod pes and
manus may have been well-suited for swimming.  Also, one might ask whether
at least some sauropods' tails might have been useful in swimming, perhaps
in a way akin to this function in some large mesozoic marine reptiles.

    (3) Could some sauropods' (e.g., Titanosaurids')  have had specialized
vertebra as an adaptation for swimming?  [Please note that this is only a
QUESTION, not a statement.]

    (4) Roland T. Bird suggested (Sorry no reference at hand.) that the
Texas track-making sauropods almost seem to have been able to vary the angle
of their toes (and, hence, claws) at will (maybe as needed).  Interestingly,
some of the manus tracks found here in Maryland suggest that  the spread of
the manus may have been variable (at will?), perhaps by slight
re-positioning of  digits 1 and 5.

    Explanation?  PURE SPECULATION:  Maybe the manus width could have been
increased as an aid in swimming, broadening its cross-section (vaguely like
the webbed hand of 'The Creature From The Black Lagoon').  Farlow (et al),
in a fascinatingly fact-filled paper describing and naming the Brontopodus
birdi inchnospecies (1989), tells us, "The indentation at the back of the
[manus] footprint, and the shallowness of this region, suggest that the
manus in life had a horseshoe-like shape, with relatively little development
of a fibrous pad behind the metacarpals."  While this shape might have been
an adaptation aiding nest building, I wonder whether the broad indentation
at the back of the manus might also have aided in swimming.

    One thing is clear, we have many more interesting things to learn
concerning these great animals.  Bring on the time machine!

    Ray Stanford