🚀 go-pugleaf

swf@tools3teradata.com (Stan Friesen) writes:

>In article <C0Dt77.Cnn@newcastle.ac.uk>, w.p.coyne@newcastle.ac.uk writes:
>|> --------------------------------------------------------
>|>    Why did mammals evolve large brains 250 Ma?
>|> Reptiles of 300 Ma, dinosaurs and modern reptiles all have the same 
>|> brain size.

>Well, right off. you start out with something that is not true.
>Birds have substantially larger brains than reptiles - in fact their brains
>are almost as large as those of mammals. (Though the enlarged portion consists
>of the optic tecta and the corpus striatum, rather than the cerebral cortex
>as in mammals).

I've checked the summary I wrote and I can't find any mention of 
birds.  The New Scientist paper did make the ocassional mention of
birds, but I did not bother mentioning those bits.

   The paper says "Jerison discovered that repiles were
small-brained 300 million years ago and remain so today.  
His plot (logarithmic) of brain size against body size for
every known reptile species, extant and extinct, produced 
a straight line.  The
dinosaurs, many of which had much bigger bodies than living 
reptiles, fall
squarely on this line, belying the myth that they lumbered to 
extinction because they were especially stupid."   It then later
mentions about birds and mammals having similar brain sizes.

                -----------------------
  You say birds have brains almost as large as mammals.  According
to some of Jerison's work there is actually a massive overlap between
the brain size (relative to body size) of mammal species and of bird 
species

   I've come across several references to Jerison's work on
brain size, and plan to send some information and questions into
the net soon on it.

>Stanley.Friesen@ElSegundoCA.ncr.com