I am not sure if this answers your question, but nor am i sure
that anyone else did either. Perhaps you might try
Kumar S, et al.
A molecular timescale for vertebrate evolution.
Nature. 1998 Apr 30;392(6679):917-20.
PMID: 9582070; UI: 98241226.
or
Hedges SB, et al.
Continental breakup and the ordinal diversification of birds
and mammals.
Nature. 1996 May 16;381(6579):226-9.
PMID: 8622763; UI: 96208645.
Pubmed has a lot on the subject I think. Hope this helps, or at
least doesn't wast your time.
-Roman Johnson
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"Think you can, think you can't; either way you're right."
-Henry Ford
