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RE: Brrr, bone chilling paleopolar summers(Polar dinosaur growth and other new papers)



  But that's my point. I'm not saying that the reptiles (however narrow that 
concept seems to me now, and it should) could not migrate, but that migration 
if it were applied from the mammalian type to the reptilian would involve 
necessary signatures: We should find similar arctic to subarctic patterns in 
reptiles as in mammals. 

  Do they exist? 

  The data is showing instead endemism: I will argue this now, as I think it 
more correct so far than has been asserted before, that the taxa we find in the 
arctic are endemic. We can label them into convenient and more expansive clades 
in order to fit them into our moulds, but the taxa appear to be morphologically 
distinct nonetheless. This is true in dental samples from the Prince Creek and 
the various Victoria/South Australia fossils. I am also certain that the hot 
air I spew here is tempered by the fact of missing information: we are not so 
fully well-sampled that we can make such bald assertions without being 
vulnerable to attack.

  Greg Paul is relying on the fact that we lack the distribution of fossils to 
assert that we are correctly sampling the fauna in order to constrain our 
theories to fit. This is easily assailable because it's reflected by sampling 
biases. Supporting a sampling vacuum as a reflection of the real faunal record 
does us no good.

  Similarly, my own assertion that taxa are distinct between the two is based 
merely on dental sampling: We've argued so far that fauanl records show that 
Prince Creek and southern Alberta show similar taxa, but these are often 
referred on the basis of incomplete material (most of it teeth) or general 
similarities; the latter is based on the asusmption that *Chamsposaurus* means 
all of its species, rather than each species being unique in its own right. Not 
all species of *Phocini* are migratory, not all are arctic, not all are deep 
water predators, etc. [we can further constrain this to *Pusa*, containing the 
circumarctic *hispida* and the lake-locked nee estuarine wanderers *sibirica* 
and *caspica* to the same "taxon"]. Constraining behavior and biology on the 
basis of an inflated taxonomic grouping is another form of bias.

  It's about perspective, in short.

Cheers,

  Jaime A. Headden
  The Bite Stuff (site v2)
  http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)


----------------------------------------
> Date: Sun, 7 Aug 2011 23:49:37 -0300
> From: augustoharo@gmail.com
> To: dinosaur@usc.edu
> Subject: Re: Brrr, bone chilling paleopolar summers(Polar dinosaur growth and 
> other new papers)
>
> 2011/8/7 Jaime Headden <qi_leong@hotmail.com>:
> >
> >   Your inference here, then, is that marine reptiles migrated, which would 
> > imply they have a similar metabolic constraint and allowance as marine 
> > mammals do which also migrate.
>
> You mean, similar metabolic constraint and allowance in what sense?
> Because Dermochelys is very active, yet have a basal metabolic rate
> well below that of a similarly sized mammal, and it has been described
> as migratory (http://www.seaturtle.org/PDF/James_2005_EcolLett.pdf).