[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: cause of Gigantism in sauropods



David Marjanovic writes:

<how often elephants or cape buffalo are attacked, and how much the males 
participate in the hunt, varies between cultures:>

  It's a trend of human psychology: To cite the sensation, unique, over the 
characteristic, mundane. It is far more common to see citations of unique kill 
events in the Savuti than it is to record the day-to-day ordinary kill events. 
When the latter happens, it's a statistic so small it hardly influences the 
overall number; the former, on the other hand, has a LARGE statistical effect 
in the sample, so much so that it is conspicuous. This makes it noticeable by 
convention, and the more they happen, the more noticed they are ... they may 
even become mundane by reportage, because the value of other kills is 
diminished in comparison.

  While it is unreported generally about the timing, average and therefore 
normative participation and prey is pretty statistically damning of exceptional 
events.

<The skull of *Allosaurus* in particular has been compared to a hacksaw. Lions 
pierce, crush and rip instead.>


  Lion canines, much like leopard ones (and jaguars) are blunt for the crushing 
bit. They even sometimes have carinae. This probably helps enable the piercing 
bite more than the tearing action of the jaw. But it is jaw strength and not 
tooth form that helps lions crush anything; they selectively use their limbs 
and teeth to disable and render, rather than opting one set of tools for a task 
(which is the pattern for other big cats). This is comparable to bears, which 
they share similarities to in canine morphology.

  Also, the comparison of the *Allosaurus* skull as a hacksaw is 
enormously oversimplified and, I think, inaccurate: A hacksaw's teeth 
are arrayed in an alternating splay, effective on both a push and a pull
 (most normal saws have special teeth that are oriented to permit both, a
 hacksaw is designed primarily for the push stroke), while an 
"allosaur"'s jaw is only effective on a pull. Similarly, a hacksaw is 
ineffective when the edge of brought down on a plane, while this action 
is used to promote the image of the allosaur skull as a "hatchet" 
(Bakker's term). This is because a theropod tooth is, primarily, a 
piercing device (always) with a cutting edge (maybe), not a double-bit 
edge with a blunt terminus. And all theropods must gain leverage with a 
piercing strike followed by a pull -- variation tends to involve in how 
and in which direction the pull occurs, such as leverageing with the jaw
 instead of the body and pulling up rather than back, or altering the 
angle of jaw to ground and pulling in the direction of the jaw from the 
ground (lifting vertically).

Cheers,

Jaime A. Headden
The Bite Stuff (site v2)
http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)