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Re: late night thoughts: misunderstand what?
----- Original Message -----
From: "don ohmes" <email@example.com>
Sent: Sunday, June 17, 2007 10:13 PM
........... I think it unlikely that the first seriously big theropod
appeared before or after the first seriously big sauropod (within the
margin of error). They probably moved pretty much in lock-step.
There are tracks of very large sauropods in Middle Jurassic strata. IIRC
there are no hints at seriously big theropods from that time; those start
with *Saurophaganax* in the Late Jurassic.
From the functional perspective, top herbivore/top predator form a
predation pair. The fact that the most extreme cases of giantism in both
occurred simultaneously in geological time
Is that a fact?
*Giganotosaurus* and *Argentinosaurus* do occur together. But neither
*Tyrannosaurus* nor *Tarbosaurus* have huge sauropods at their disposal;
*Puertasaurus* lived across the sea. Are there even enough giant theropods
to qualify for a statistically meaningful sample?
is, in my view, evidence for an arms race (I term I dislike, but have no
immediate substitute for).
Why should only the upper end of the size spectrum participate? If the
biggest sauropods are just a bit too big for the biggest theropod, and
somewhat smaller prey is available, shouldn't we expect the predator to
shift to that smaller prey? If said prey has no other defense than to grow
larger, soon _all_ sauropods will be at the upper end of the sauropod size
range. I can't see how you can avoid this -- falsified -- prediction.
Further, vulnerability does not equal extinction. Consider the amazingly
vulnerable and evolutionarily enigmatic 'possum (American style). Restate
your point, and then think about it.
How is the opossum "amazingly vulnerable"? It can play dead very
convincingly, it can climb, it has canines a bit longer than mine, and it
breeds faster than predators can keep up. I also can't see anything
"evolutionarily enigmatic" about this.
If the level of vulnerability required for an arms race was defined by
extinction, there could no arms races...
I don't see where you get that from. Arms races never have winners -- those
that have winners end too soon to be noticeable.
that said, I am more interested in your evidence _against_ selective
symbiosis (arms race).
You predict (see above) a trend of consistent increase in sauropod size.
There is no such trend. Quantum electrodynamics, I mean, QED.
...... I think that when it was practical (prey density= proximity
probability, mostly), it was very easy. The ability of prey animals in
general to detect immobile objects is over-rated by many in my opinion. I
base this on personal experience w/ white-tail deer and wild turkeys,
which if you are patient you can get VERY close to, in zero cover.
Understandably this is not convincing to a scientist, or even some
inveterate hunters. Can't move your eyes at all w/ the turkeys. They get
the picture then. -- DO.
Try to overlook a full-grown *Tyrannosaurus* in a landscape a sauropod can
walk through. That can't be easy.
That pine log has no muscles in it... but that probably doesn't matter.
matters is that you assume that sauropods held their necks very close to
ground most of the time -- which was clearly the case for some, but not
necessarily for all --, and that you overlook the possibility that a
sauropod might swing the neck around as a weapon, the same way as the
Sure, sauropods would have avoided using the head as a tail club for
reasons, but being struck by the middle of a sauropod neck can't have been
very pleasant experience either.
........... Well, the idea of the pine log was that it is assumed to be
'stronger' than a neck.
My point is that it isn't necessarily; muscle work can keep joints from
I think if the strike missed there was ample time for predator get-away,
...unless the tail or a forelimb hit.
How? The head is 10 m from the feet in standing position. Now we are
delving into an area of sauropod mysticism I have just never gotten, even
when I was 8. If I am lurking under a tree like a rattlesnake (for
example), and a foraging sauropod wanders close enough for me to try to
grab it's head, and I miss, how am I in any danger?
How probable is it that a sauropod would get its head that close to a
predator? Much, much less probable than getting its head that close to a
rattlesnake-sized object. I'd attack a sauropod by running at it from a
side, with wide-open jaws. That's what *Allosaurus* seems to have done,
judging from its very strong skull that is way overdesigned for the puny
bite forces *A.* could generate.
Will it pirouette and smack w/ its tail so fast I can't back away?
Surely a flagellicaudatan can bend its tail by more than 180°? Not that it
matters much, though -- see above.
Can it follow me into the trees?
Why should it? As long as you stay there, the sauropod is fine.
Why shouldn't a sauropod be able to kick much faster than it usually
..... Some. But not much. Heh. "Kick away. I am up here by yer ol' punkin
You're probably not. Because if you were, all sauropods would have died out
in the Late Jurassic at the very latest.
What for? Nutritional value close to 0.
........ Already mashed up and in my mouth? From me drinking the arterial
blood gushing like a high pressure hose out of your body? Apologies to the
kids, but this sauropod invulnerability thing is proving hard to crack
from the cultural perspective. Vivid images may be required. -- DO.
"Drinking"? What about "being washed away by it"? Or at least blinded, as