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Re: _T. rex_ strikes ( was Ceratopsian frills)



Joe Daniel writes:

>Snakes and a variety of birds, ala ostriches and secretarybirds, 
>display blinding speed as well without the need of the short neck.  

_T rex's_  big head was about 6 meters from its center of mass.  Police
use sledge hammers on doors, but could you hit a moving person where you
intended if you used a sledge hammer as a nightstick?

>Teeth work reasonably well as long as they are big.  Smilodons 
>apparently succeeded in bringing down the giant ground sloths or young 
>mastodons.

You caught me!  For penetration, _Smilodon's_ strongly anchored canines
were a lot longer than its other teeth.  It had claws to help it hang
on.  Compared to other cats, its center of mass was closer to its head. 
This way, its large size wasn't such a problem when prey tried to toss
it off.

>...I have a hard timeseeing how those teeth are anything approaching 
>fragile.  They are at least as strong as crocodile teeth or shark teeth
> and they do just as well. Remember, the strength of the teeth needn't 
>be scaled upwards to their body size or anything like that.  They 
>simply have to withstand cutting through flesh and maybe bone and that 
>they do just fine.  The size of the piece they cut through doesn't 
>really matter.  Besides, they grew back fairly quickly so if they lost 
>some regularly, so what? 

Weren't America's plains once overrun with millions of buffalo whose
size made them fairly invulnerable to wolves?  Why didn't wolves get
bigger?  I understand wolves have never been dramatically bigger than
they are now.

I think the size limitation came from the way wolves attacked, clinging
with teeth alone.  As a buffalo tried to throw a large wolf off, the
strain on its teeth and neck could be tremendous.

_T rex_ had perhaps 80 times the mass of a wolf, and this mass was
centered perhaps 10 times as far from the jaw.  Suppose _T rex_ bit into
a huge sauropod's bony shoulder.  When the prey reacted, the awesome
force would be unevenly distributed on the teeth.  If some broke off,
wouldn't others follow?

_T rex_ could end up on the ground.  If he could elude the prey's feet
and tail and had the stamina to renew the attack, wouldn't a big gap in
his teeth be a problem?  If he completed the kill, it might be hard to
eat, particularly if smaller, more agile meat-eaters were grabbing what
they could.  How long would it be until he could hunt again?

Some theropods were built like destroyers and others like battleships. 
I imagine the "destroyers" had agility and stamina, like dogs.  

It's the "battleships" I wonder about.  By the process of elimination,
some say _T rex_ was a scavenger, driving hunters from carcasses.  How? 
A lion can chase away smaller predators by swatting, lunging from a
crouch, and turning fast.  Was _T rex_ built for any of these things?

I think _T rex_ used impact because I don't see how it could have
attacked like a wolf or like a tiger.

>Naturally its strenth was concentrated in its legs.  So is yours and 
>any other bipeds.  I know my legs can can lift an order of magnitude 
>than my arms can.  But which one am I likely to use in attacking 
>someone?

I assume _T rex's_ arms were not its primary weapons. 

>Actually, jumping completely off the ground in some kind of a grandiose
> highflying kick increases your vulverabilty rather than the opposite.

The leap would have been so low that _T rex_ would have had to "lie
sideways," like a human vaulting a fence.  As the 2-to-3-meter height of
a typical sauropod's neck would have been knee-high to _T rex_, it would
have been like a human baserunner launching himself feet-first toward a
base.

A baserunner goes in feet-first to get in fast while minimizing the risk
of injury.  This also allows him to clobber the baseman.  

I think this approach would have allowed _T rex_ to strike a mortal blow
before getting whacked by a tail.  At 10 meters per second (like a human
runner), _T rex_ would have had the momentum of a four-wheel-drive
pickup truck at 60 mph.  

I use _T rex_ as an example of an impact hunter because I don't have
pictures and data for other tyrannosaurs. I think it was other
tyrannosaurs, who appeared earlier, that specialized in sauropods.

In the Jurassic, I understand there were a lot of sauropods and
stegosaurs, long-necked animals who could have eaten tree leaves and
used their tails to strike predators.  The stegosaurs and most sauropods
disappeared about the time tyrannosaurs appeared.  

I understand most surviving sauropod species were related to
_Brachiosaurus_, whose neck was a startling 6 meters off the ground.

Have I made many errors?  (Like somebody wandering in a cow pasture, I
wish I were better at stepping carefully!)

- Stephen Throop