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Re: Fw: late night thoughts: misunderstand what?

----- Original Message ----
From: Andreas Johansson <andreasj@gmail.com>
To: d_ohmes@yahoo.com; dinosaur@usc.edu
Sent: Sunday, June 17, 2007 5:06:34 PM
Subject: Re: Fw: late night thoughts: misunderstand what?

On 6/17/07, don ohmes <d_ohmes@yahoo.com> wrote:

> ........... 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. 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, in my view, evidence for an arms race

Simultaneous occurence means nothing if you've got non-overlapping
ranges. *Tyrannosaurus* and *Puertasaurus* are both Maastrichtian and
of near extremal size for thero's and sauro's respectively, but found
on different continents. The sauropods actually known from tyrannosaur
turf are, AFAIK, all comparative runts.

............. It seems to me that late in the game, finding the respective 
maximals well-separated might be viewed as support for a theropod/sauropods 
size race that began 'at the beginning'. Which, of course, I think the 
predators won. By which I mean that the sauropods could no longer maintain a 
favorable height differential w/ the theropods by increasing their size. My own 
_T. rex_ cartoon is that _T. rex_ is what you get when you gradually take 
(most) of the sauropods away from sauropod-eaters that use a still-hunting 
strategy, in loosely associated groups; as prey availability decreases, 
intra-specific competition increases (especially at the carcass), and therefore 
predator size increases. Eventually the primary food source is no longer 
sauropods. As prey size decreases, eventually everybody has to go solo. Because 
the smaller herbivorous dinosaurs were actually harder to kill than sauropods 
(especially solo), predator size and speed continued to increase, culminating
 in _T.rex_. I add speed, because the speed and/or distance of the final lunge 
obviously became more important w/ time in this scenario. That said, all of the 
animals in the fossil record took a long time to evolve and preservation is 
very spotty. I just don't think it is accurate enough to be used to falsify 
basic eco-evolutionary theories (like predator/prey size races) on the basis of 
relatively small time slices. -- DO.

> (I term I dislike, but have no immediate substitute for). Further, 
> vulnerability does not equal extinction. Consider the amazingly vulnerable 
> and evolutionarily enigmatic 'possum (American style). Restate your point, 
> and then think about it. If the level of vulnerability required for an arms 
> race was defined by extinction, there could no arms races...  that said, I am 
> more interested in your evidence _against_ selective symbiosis (arms race). 
> Finally! A potential substitute for 'arms race'. Maybe. -- DO

Calling a predator-prey relationship "symbiosis" is perfectly perverse.

--------- Well, you have me there. But, hey, they are giving each other 
selection, right? -- DO.
Andreas Johansson

Why can't you be a non-conformist just like everybody else?