S.pombe/S.cerevisiae divergence

[JMH14 at phoenix.cambridge.ac.uk]

I am looking for some hints on estimated dates for the Saccharomyces/
Schizosaccharomyces divergence. The only data I have come across so far is
a 5S tree from Rupert De Wachter's group which suggests (implicitly rather
than explicitly) a divergence time of 1,000 MY or so. This was published in
1983/4. Does anyone know of more recent data, perhaps based on 18S sequences (?)
I would be grateful for any pointers.

John Hancock
Dept of Genetics, University of Cambridge, U.K.