RE: [RE: Dinosaur tail dragging]

["Stewart, Dwight" <Dwight.Stewart@VLSI.com>]

Okay, I believe you are correct (from watching "The Crocodile Hunter" on The
Animal Channel).  :-)
In any event, dragging a heavy tail would certainly be a problem, due to,
well - drag.
On this subject, I was examining a cantilevered silicon carbide loader in
our fabrication area tonight & by definition, it is attached at one end (the
fulcrum) & free-standing on the loader end, which holds up ~ 50 kgs of
material with maybe 1 cm of bend from attachment to end.  I helped design
this system around 5 years ago & a key feature is the robust under carriage,
which works much like a powerful tendon would.
This strut runs past the fulcrum point by 20 cms, which we designed
specifically to hold the extension as close to absolute horizontal as
possible.  This design could be used to hold up essentially any amount of
weight for any distance as long as sufficient reinforcement is used &
extended far enough past the fixed side of the fulcrum.  Nature has a habit
of designing things first, so a very long, very heavy tail could certainly
be held at horizontal the same way.  

Dwight  

        -----Original Message-----
        From:   archosaur@usa.net [SMTP:archosaur@usa.net]
        Sent:   Wednesday, September 09, 1998 10:32 PM
        To:     Dwight.Stewart@VLSI.com
        Cc:     dinosaur@usc.edu
        Subject:        Re: [RE: Dinosaur tail dragging]

        owner-dinosaur@usc.edu wrote:

        Dwight wrote:

        An alligator drags its tail, BUT - look at how

        > it's body is positioned: very low, in an almost straight pull line
with the

        > tail AND with the legs sprawled out at the sides.  

        ==========================
        ==========================

        Not to be knit picky, but alligators walk in two different
        ways. The sprawled gait that they are usually associated
        with is used only for very short distance travel and is
        a bad analogue for tail dragging. 

        Now when the alligator is walking, it's body is held way
        off the ground with the legs held in towards the body ins 
        a basically erect fashion. In this position 2/3rds of the tail 
        are held off the ground. Plus a fast moving gator will have it's
        tail held off the ground.

        This is actually true for most lizards too. The tail is 
        usually held off the ground when in a run or trot. 

        I don't see why it would be too different for certain deinosaurs.
        such as theropods. They have their tails on the ground when 
        at rest and in the air when moving. This would account for 
        the lack of tail impressions in trackways too, since the deinos
        are supposedly on the move at that point in time.


        Sauropods would of course be a bit of a different case, just due 
        to their immense size.

        Like I said, sorry to be knit picky, but I just hate it
        when crocs are put in a bad light.

        Archosaur J.

        http://members.tripod.com/~jurassosauridae/index.html

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