Re: Not dinosaurs

["Nicholas R. Longrich" <longrich@phoenix.Princeton.EDU>]

On Fri, 26 Jan 1996, JCMcL wrote:

> On Fri, 26 Jan 1996, Bob Myers wrote:
> 
> > If you want to minimize surface area, you make rounded shapes. A
> > conical tail is the wrong shape.  You'd want a very flattened tail if
> > you wanted to maximize the surface area.  That's one reason why some
> > people propose sails or stegosaur plates as radiators - they're flat!
> > 
> > Bob Myers                              InteleNet Communications, Inc.
> 
> Best explanation I've heard yet!  Keep them coming!
> Another question on sauropod cooling: did these animals have air sacs as 
> birds and (presumably) many theropods did?
> How extensive would these sacs have been, one wonders, and how far into 
> the neck and tail would they have reached?
> How effective would the circulation of the air through these sacs have been?
> 
> I am simply mystified as to how a sauropod kept from overheating, 
> particularly one of the really large economy-sized models.  
> 
> Thanks for all the well-meaning commentary!
> 
> John McLoughlin, who hath no tail, conical or otherwise
> 
if big tails served primarily as radiators, we would expect to see 
them on the really huge beasties like brachiosaurs, but they aren't. 
Camarasaurus approaches Apatosaurus in size, as well, and it's a short-
tail, while Dicraeosaurus is a small, but whip-tailed, sauropod. 
 Also, if they served as radiators, we would expect 
them to be flattened, probably with long neural spines and chevrons.
        Tail weaponry is pretty common- ankylosaurs, stegosaurs, 
diplodocids and shunosaurus all had tail weaponry. Weapons 
weren't all they were using their tails for though. With the exception of 
ankylosaurs, massive hips, huge hip spines, and short forelimbs, 
among other things, indicate that they were rearing up and back onto the 
tail and hindlimbs frequently. That's why the tail probably got big and 
powerful in the 
first place, turning it into a weapon was an exaptation. 
        What Bakker claims about sauropods is that the pleurocoels were 
filled with air sacs, allowing a cooling system. One possible problem 
with this idea is that in some species, the pleurocoels were closed. 
        There was also supposed to be a sort of skin ridge found on part 
of a diplodocus- well, actually, from the tail- a few inches high, with 
sort of an up-and-down zigzag, like what you'd draw on a dragon, or a 
cartoon dinosaur. Something like that, running the entire 90 ft. of an 
Apatosaurus' back, might do a little to help lose some heat. Perhaps some
of them also had some nice dewlaps- those are pretty common on modern 
sauropsids. Then there's Amargasaurus, but the animal is kind of small to 
need radiators- but then, even jackrabbits make use of heat radiators. 
        
        -nick L.