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Re: comparative color vision



At 12:10 PM 5/21/99 -0500, Mickey P. Rowe wrote:
>Sorry to gore another ox, but given the available data the most
>probable condition for cows is that they (like most mammals) have two
>cone classes and hence dichromatic color vision...

This agrees with my understanding - virtually all mammals, with a few odd
exceptions (such as primates), have dichromatic vision.
>
>Many (if not most) birds have four cone classes.  So do at least some
>lizards, turtles and alligators.

So, by crude application of phylogenetic bracket, we arrive at the
conclusion that dinosaurs were probably tetrachromats, right??  (I seem to
have missed or forgotten that most vertebrates are tetrachromats).

[This could be checked a little better by comparing the amino-acid sequence
in the pigment molecules in birds and crocodiles, to see if all four
classes are homologous between the two groups].

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