Re[2]: Theropod tail question

["Cunningham, Betty" <bcunning@nssi.com>]

     this is a copy of something I was asking way back in August and 
     several people were very helpful in describing the motion.  I'm 
     sending this one 'cause it has diagrams.....)
     
     -Betty
     -----------------------------------------
     >>Because cheetah (and other cat tails) do not have the complex 
     >>structures in the tails of dromaeosaurids etc., they do curve and 
     >>bend while they move. If you watch slow speed films and stills of 
     >>big cats hunting, you'll see them holding them out and up behind 
     >>them, probably the way dromaeosaurids did as well.
     
     >However, though the tail is stiff, it curves in a variety of ways     
     >that I don't see the reinforced tail of therapods doing.  Just how 
     >flexible do the tendons allow the tail to be?  Are we talking full 
     >rotation of the tail at the point it joins up to the hip? 
     
     >>The tails of dromaeosaurids were incredibly stiff (one of the MAJOR 
     >>anatomical flaws of Jurassic Park was the raptor tails; another was 
     >>the raptor hands).  In dromaeosaurids and birds, the motion would 
     >>all be in the five-to-nine most proximal caudals. In other 
     >>tetanurines, the tail was more flexible, especially out to caudals 
     >>12-15 (coelurosaurs) or 20 (allosauroids and others).  In 
     >>ceratosaurs, the tails were very flexible.
     
     Having only seen the tendons in illustrations that were all from the 
     side of the animal, can I ask you for clarification?  (I gotta draw 
     pictures at this point, can't help it, it helps me be clearer)
     
     Top view of tail:          <--head  
     
     __(hip)              /\(motion)
     {_______}            
     @  @  @  @  @  * * * * * * . . . . .
     [=][=][=][=][=][=][=][=][=][][][][][][][][][][][][][][][][]
     _______
     {_______}             
     \/(motion)
     
     where @=dromosaurids
     *=coelurosaurs
     .=allosauroids
     
     Which way is this flexible? to the animals' right and left?  to the 
     animals' top and bottom?  The tendons that reinforce this area (again, 
     I've only seen this from the side view) seem to prevent up and down 
     motion and aid side-to-side motion, but in a limited fashion.
     
     
     Side view of tail:        <--head
     
     /\(motion)
     
     @  @  @  @  @  * * * * * * . . . . .
     [=][=][=][=][=][=][=][=][=][][][][][][][][][][][][][][][][]
     ________ 
     {___ \___}
     /  \                \/(motion)
     /    \
     (hip)   \
     
     -Betty Cunningham
     (bcunnin@nssi.com at work)
     (bettyc@flyinggoat.com in the studio)
______________________________ Reply Separator _________________________________
Subject: Re: Theropod tail question
Author:  aimnet!PLU.edu!pharrinj
     
> I know many theropods had stiff tails because of thier vertabrea.  But 
> were they completely stiff and unmovable?  This doesn't make any sense to 
> me.  Surely they could move them a little.  This is what I picture.  A 
> theropod is stalking through the thick foliage.  It knows the prey is 
> near. He can hear and smell them.  They are not that far ahead.  He turns 
> to conceal himself under the leafy undergrowth when WHAP!  That stiff 
> tail held out behind him slaps against some plants.  The sound carries 
> through the air like a thundrcrack.  The prey's head whips up and it runs 
> off.  The poor theropod sits there growling to itself because it just 
> missed a meal.  Is what I picture happening very offten it you have a 
> long tail that can't move.  Tell me know what I'm missing here.  Thanks. 

     
   >>The theropods with the stiffest tails were dromaeosaurs, which 
>>possibly did not live in forests??  Anyway, the BASES of the tails of 
>>all theropods were quite flexible, even if the last two-thirds or so of 
>>the tail was stiffened.