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late night thoughts: misunderstand what?

On 6/18/07, don ohmes <d_ohmes@yahoo.com> wrote: 


----- Original Message ----
From: Andreas Johansson <andreasj@gmail.com>
To: d_ohmes@yahoo.com; dinosaur@usc.edu
Sent: Monday, June 18, 2007 5:57:06 AM
Subject: Re: Fw: late night thoughts: misunderstand what?

On 6/18/07, don ohmes <d_ohmes@yahoo.com> wrote:
> AJ-- "Your idea need to be anchored in actual spatiotemporal distributions of 
fossils."
>
> They are. Sauropods and theropods both appear in the Late Triassic aka 'the 
beginning'. They coexist until KPg... aka 'the end'.

You said that the largest thero's and sauro's occured simultaneously.
Retreating to that they both occured in the Late Triassic to end
Cretaceous isn't merely stretching the idea of "simultaneously", it's
cutting it in two.

------------ Come again? The largest occurred in the Triassic? I didn't say that, and it is not the case. 

You want to argue that thero's and sauro's were involved in a size
race. Simply stating that the biggest of each lived simultaneously or
that they coexisted throughout the Late Triassic to the end Cretaceous
isn't enough for that: you have to point to instances of thero and
sauro lineages that plausibly interacted with one another growing
larger in tandem.

And your second sentence isn't clear to anyone I've showed it to... so??? -- DO. 

Very simple: you claimed that the biggest sauro's and thero's lived at
the same time, and when I asked you to specify when and where you said
they lived throughout the LTr to the KPg.

> Our perspective on evolution is evidently very different. I don't think that 
the end theropod being the biggest, and the end sauropod being the most armored, 
and quite large, does anything to falsify the notion of a prey/predator size race.

If prey not getting larger doesn't do anything to falsify the notion
of a predator/prey size race, what on earth would?

.............. Are you saying there was no thero/sauro size race and the fossil record shows that? 

If you are saying that there was *a* thero/sauro size race that went
on for the duration of their 150M-odd coexistence, I do say the fossil
record shows quite clearly that was not the case. If you're saying
there were some such races going on during shorter timespans involving
sublineages, I am merely asking you to provide examples where you
think that happened. I've also pointed out a specifc instance where it
didn't happen - tyrannosaurs vs. *Alamosaurus* and ilk.

Also, prey not getting larger when? In general, or specific to the thero/sauro case? 

Not getting larger when the Tyrannosaurs got large. This is a
counterexample to your model of thero's and sauro's getting larger in
tandem.

I make every effort to be clear... 

I am afraid your success has been mixed.

I seem to be faced w/ the concept that if prey size does not increase to 
infinity, or there is not total extinction of prey, then a size race has not 
occurred, but I am not sure. -- DO.


Not at all. You are faced by a) the fact that thero's and sauro's did
not grow continuously larger across the Jurassic and Cretaceous, and
b) requests for specific examples where you think size races occured.

> That T.rex evolved separately from the allosaurids seems indicative to me 
that the evolutionary sub-strate was conducive to creating mega-predators.

Certainly, but an environment conducive to the evolution of
mega-predators does not equal a size race between those mega-predators
and mega-sauropods, especially not for those mega-predators that, as
far as is known, did not coexist with mega-sauropods.

.........Are you saying there was no thero/sauro size race and the fossil 
record shows that?  -- DO.


See above.

--
Andreas Johansson

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