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Re: late night thoughts: misunderstand what?

On 6/20/07, don ohmes <d_ohmes@yahoo.com> wrote:
----- Original Message ----
From: Andreas Johansson <andreasj@gmail.com>
To: don ohmes <d_ohmes@yahoo.com>; dinosaur@usc.edu
Sent: Wednesday, June 20, 2007 9:38:56 AM
Subject: Re: late night thoughts: misunderstand what?

On 6/20/07, don ohmes <d_ohmes@yahoo.com> wrote:
> You seem to be saying that for every large sauropod in the fossil
> record, I must produce a large theropod of exactly the "predicted" size
> and exactly the "predicted" age, or the concept of size race is invalid. The 
level of specific proof you require is not
> now and never will be available from the fossil record, in my opinion.

That's not what I'm saying at all. I asking you to provide an example
of co-occuring sauro and thero lineages increasing in size in tandem

.............. which requires evidence from the fossil record, of the type I described.

No it doesn't. Finding a large thero' for every large sauro' doesn't equal finding one example of lineages growing big in tandem. And if the later cannot be found, your idea is untestable.

> While I cannot prove they were there, a trip on my part to the time and place 
of Alamosaurus would entail preparations for an encounter with a large carnivorous 
biped. If you were going along for the ride, I think you would feel that wise, 
would you not?

Now you're not making any sense at all - *Tyrannosaurus rex*, the best
known giant theropod bar none, is from that time and place. What's not
known from that time and place is a seriously big *sauropod*.

............pick a big sauropod, any big sauropod. Gosh, good one.


> By known ecological principles, evolutionary theory, and uniformintarian 
principles; showing that theropods and sauropods co-existed throughout their 
history, AND that valid predation scenarios exist, is indeed enough for me to 
argue, even assume, that they were in a size race, one that was continuous and 
operated on all the large lineages.

A continuous size race, by definition, means a continuous size
increase. A continuous size increase did not occur. Ergo, there was no
continuous size race.

This is elementary logic. Why is it so hard for you to understand?

..........I am just really, really dumb. And simplistic. Why else would I do this? What 
you describe below, after the words "fallacy of..." is what I call a continuous 
size race. I also never said that ALL theros drove all sauros, or vice versa. Not quite 
that simplistic.

See below.

> I never said or thought that it was the ONLY size vector, that is not the way 
ecosystems work. In fact, the idea that standard top predator/top prey 
relationships was NOT a major driver of sauropod and theropod size is new to me, 
and I am sure to many other folks. But, as I am sure you have noticed I am out of 
touch. I wonder what you have to replace it.

Fallacy of the excluded middle. Rejecting a continuous 150+Ma size
race 'tween thero's and sauro's does not imply rejecting top
predator/prey relationships between them. Neither does it exclude that
size races may have occured 'tween certain sub-lineages: this why I
keep asking for instances of lineages growing in tandem.

........That is what I call a continuous size race. Continuous top/top relationships 
over time. So in my terms, "Rejecting a continuous 150+Ma size
race 'tween" is rejecting top/top relations.

Then you need to do something about your terms. Using continuous to mean discontinuous and top predator/top prey relationship to mean size race guarrantees getting misunderstood.

Within lineages any top/top prey/predator relationship is a size race when viewed over time.

No. The lineages may have gotten big before meeting, and/or gotten big for reasons unrelated to one another, just for a start.

Most reach equilibrium. In some cases, somebody wins. I think with 
sauros/theros somebody won a lot, in the sense described by 'L1,2,3,4'.  What 
is your evidence of equilibrium between thero/sauros?

Equilibrium in *all* cases? I don't think there was.

> I do not see that a 'ceiling' on size through the Jurassic/Cretaceous (taking 
everybody's word that it exists) invalidates such a bedrock ecological concept. I 
have always been a big fan of the idea that there are limits to size inherent to 
the laws of physics, and that these are modified downward by local conditions. It 
is one of my core assumptions.

Another of your core assumptions, it would seem, is that you can
increase in size without getting bigger.

.......... now that is nonsensical. Care to explicate? Separate post?

Quite simply your insistance one can have a continuous size race in the absence of a continuous size increase. I could hardly know that in your usage, continuous doesn't mean continuous, could I?

> To repeat from last night, slightly edited: Here's what I don't understand 
about the 'take' on size trends.
> Lineages 1,2,3,4,... recorded through time. Each gets big, hits an apparent 
ceiling (size limit), then sputters, dies.
> How
> does that negate predation as driver, and 'predators won" if the size
> limit is real?

If the predators won, the sauropod lineages would go extinct an
geological instant after hitting the ceiling; they couldn't "sputter",
since, under your scenario, any sub-size descendants would get eaten
even faster than those who merely failed to grow bigger.

............my scenario includes refugia. ALL my scenarios include at least the possibility of refugia, because reality includes the possibility of refugia. I think they might sputter. What you describe is the scenario you have _ascribed_ to me.

And the reason you get things wrongly ascribed to you is that you don't express yourself clearly.

Of course, bounteous small sauro's remain a problem for your refugia
idea; see below.

BTW-- what is your explanation for size of sauros, generally?

That they grew big in the first place I would think was to get big guts for fermentation - very useful if you eat low-grade food of the kind sauro's are thought to've subsisted on. Why certain lineages eventually grew gigantic I don't have any particular opinions on.

You might more productively ask this question to a sauropod expert.

Also, this really shouldn't need to be pointed out, but what you're
describing here isn't a continuous anything - it's a *dis*continuous

.................see Tim's last post. "...Within each of the major
sauropod lineages (diplodocoids, brachiosaurids, titanosaurs) average size
appears to have peaked, and then gone downhill." The same process can occur 
simultaneously or sequentially, as long as the ceiling is in place. "This is elementary 
logic. Why is it so hard for you to understand?"

Because of your wanton abuse of the English language.

> The "little" guys found refugia, possibly because large bipeds don't like 
soft ground. Or for a multitude of other reasons.

If the little guys where restricted to refugia, the smallish
camarasaurs wouldn't be the most common sauropod fossils in the
mega-thero'-infested Morrison formation, nor would saltasaurines be so
common in the Late Cretaceous. The only reasonable conclusion is that
the "little guys" were able to coexist with mega-thero's.

........ why not? Refugia can have excellent preservation, or none at all.

The Morrison is huge, and camarasaurs are, if I understand correctly, found all over the place, interspersed with finds of big to huge thero's.

There might be reasonable conclusions out there you haven't thought of.... that 
is a concept that applies to your take on 'sputter', too.

> Which reminds me; how many of the smaller species have a long enough presence 
in the record to prove that they weren't also increasing in size?

Some no doubt did increase in size, but clearly some didn't, because
we find small sauropods all the way from the Triassic to the end

.......... a single species, shown to maintain small size over a reasonable time span? Not saying they aren't there. Just asking.

Tell me what a "reasonable time span" is, and I'll go looking.

Andreas Johansson

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