Re: Protopenguins and pterosaurs

[Dora Smith <villandra@austin.rr.com>]

Thanks for finding this for us!

The fossils of penguins were dated by the geologic layer they were found in. 
The New Zealand Waipara Greensand, a Paleocene (early Tertiary) formation 
just above a well known Cretaceous/ Tertiary boundary site.

They state that the fossils, a new genus (Waimanu) provide a lower estimate 
of 61-62 Ma for teh divergence of penguins and other birds.   They think 
that that estabilshes a reliable calibration point for avian evolution, and 
conclude after alot of mathematical juggling and DNA sequences that modern 
crown group birds must have radiated in the late Cretaceous.

They provide an anatomatical analysis of their ancient penguin species and 
their place in cladistics that I'll let y'all figure out - I'm not 
anatomist.

Next they consider genetic relationships between the various clades of 
modern birds, and estimate when they diverged.   The correctness of that 
analysis would depend on how clades of modern birds are really related to 
each other; that is very controversial.

However, you do have to grant that it takes a certain amount of time for so 
much genetic mutation to take place.   The weakest part of their article as 
far as I'm concerned is taht they really don't go into detail on how long it 
took for the assorted species to diverge.

I would, however, be startled if, no matter when penguins evolved relative 
to other birds, it didn't take more than three million years for them to 
evolve from Basal Bird.   After all, humans diverged from chimpanzees a 
couple of million years ago!

Ancient DNA.   LOL!   Lately I 've caught even CNN making hysterical errors 
in reporting.

Yours,
Dora Smith
Austin, TX
tiggernut24@yahoo.com
----- Original Message ----- 
From: "Richard and Jo Cowen" <cowen@blueoakfarm.com>
To: "Dinosaur Mailing List" <dinosaur@usc.edu>
Sent: Sunday, April 09, 2006 4:39 PM
Subject: Protopenguins and pterosaurs


> mbe.oxfordjournals.org/cgi/reprint/msj124v1
>
> Cheers
>
> Richard Cowen



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