Re: Dinosaur tails

["Jaime Headden" <jaemei@hotmail.com>]

<Now, I thought the one thing that dinosaur tails were _not_ was highly 
flexible, like a snake.  Sauropod tails, maybe, but I've had the 
impression for several years that most theropods, and especially most 
coelurosaurs, had tails that were held more or less rigid by a
basketwork of ossified tendons.

So why do so many artists _insist_ on drawing theropod dinosaurs with
highly flexible, snakey tails?>

Only troodontids had the basket-network of tendons---none others to my 
knowledge have been found with ossified tendons. Dromaeosaurids lack the 
tendons, but have the pre- and postzygapophyses and haemal arches 
elongated and overlapping for over 15 vertebrae for the longest.

Now, the *Sinosauropteryx* that is most complete (specimen 2) was set in 
a death pose with the back, neck, and anterior tail flexed into a 
classic sign of rigor mortis, but the tail for nearly all its length is 
strait, implying a) the tail was so stiffened it _could not_ bend during 
dehydration or rigor mortis, or b) it lacked these to begin with, and 
thus could not be flexed after death.

This would make one incredibly stiff tail, and meant that the 
intervertebral joints were so derived as to prevent bending (cause for 
point "a," above). I do not know what the paper says on this issue. 
Maybe Tom Holtz or one of the other guys who've read the thing can 
enlighten us.

Jaime A. Headden

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