Re: Proto-penguins lived with dinosaurs

[frank bliss <frank@blissnet.com>]

Wow...A few deeper thoughts here.

Molecular Divergence Rates and molecular clocks assume that mutations  
occur at a stochastically constant rate......Hummm......so apparently  
there is a way to get "significant" fragments of DNA from lithified  
fossil material (I assume we are not talking about tooth pulp in  
spheniscids).  There must also be a very reliable fossil record of  
similarly preserved material for examination to show the coalescent  
time between the species divergence and the ancestor we are talking  
about here.  I was also under the impression that DNA degrades  
rapidly/significantly with time and even under extra-ordinary  
circumstances such as the recent T-rex leg bone soft tissue  
preservation do even fragments of more complex proteins (let alone  
DNA) become available for study. Not only would the DNA have to be  
shielded from the lithification process, biological (bacterial)  
degradation, desiccation and disassociation from time and a myriad of  
other obfuscating effects of post-mortum decay, it would have to be  
usable to compare to other similarly preserved DNA from similar but  
divergent speniscid samples.   I am absolutely amazed (humbled) that  
paleomolecular biology has progressed so far since I graduated back  
in the middle ages.  I don't doubt that penguins evolved before and  
survived the catastrophism at the end of the Cretaceous as did a  
representative portion of the avian dinosaur clade.  I guess I just  
don't have a grasp on the process that would allow usable molecular  
genetic molecular information being extracted from fossils older than  
around 100 thousand years old or so. Additionally, I always assumed  
that  molecular evolution occurred independently of morphological  
evolution as demonstrated in some living fossils.  Rates of the  
former do not always promote the later. Therefore any conclusion  
based on one, has limited application to the other.  I also was under  
the assumption that avian/dinosaurian cladistics did not rely on  
molecular clocks.

Frank (Rooster) Bliss
MS Biostratigraphy
Weston, Wyoming


On Apr 8, 2006, at 9:27 PM, Jaime A. Headden wrote:

> Frank Bliss <frank@blissnet.com> wrote:
>
> <No way for 60 million years old Penguin DNA!  Mantra repeat again  
> and again.>
>
>   DNA has been recovered far older than this. However, it is  
> extremely broken
> and degraded, and useless for testing. What they likely tested was DNA
> molecular divergence rates, which place the base of the spheniscid  
> clade near
> the end of the Mesozoic, either before or after the origin of the  
> Palaeogene.
> *Waimanu* itself likely only FITS into the placement implied by the  
> divergence
> timing.
>
>   Cheers,
>
> Jaime A. Headden
> http://bitestuff.blogspot.com/
>
> "Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
>
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