Re: turning turtles

[Stanley Friesen <sarima@ix.netcom.com>]

At 01:28 PM 2/24/99 +0000, John V Jackson wrote:
>>To summarise, the maximum likelihood phylogeny, based on 11 nuclear
>>proteins (1943 amino acids) was:
>>(Rodents + Primates) + (Squamates + (Birds + (Crocs + Turtles))).
>>Tuataras weren't included due to lack of data.
>> ...
>
>Proteins behave differently at different temperatures.  Warm-bloods might be
>expected to have protein strucutres that worked well over a limited range,
>but "cold"-bloods probably have pressures converging their proteins to
>optimum behaviour over a wider range of temperatures.  I would expect a
>clustering effect inside groups with similar thermal modes.

There is another factor that *may* be relevant here - long branch
attraction.  There is considerable time depth back to the
lepidomorph-archosaurimorph split, and (in the traditional cladogram) an
even *longer* time depth to the split of the chelonians.

[The same problem may be showing up in the studies that link whales to hippos].

--------------
May the peace of God be with you.         sarima@ix.netcom.com