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Re: mammal mystery

In a message dated 97-02-16 19:57:00 EST, jbois@umd5.umd.edu (John Bois)

<< Increasing size doesn't mean thriving; it means increasing size.  If you
 ask me, a group of species which keeps no really small things (moussize)
 among their members is doomed. >>

Perhaps not mouse-size, but surely with body plus tail with length less than
about 50 cm (like a very large rat). This happened with >all< the dinosaur
groups except birds by the end of the Cretaceous, which is likely why the
only "dinosaurs" that returned following the terminal Mesozoic extinction
event were the giant flightless birds, such as diatrymids. There were several
partial extinction events during the Mesozoic that did not do in all the
dinosaur groups--just those, such as prosauropods, stegosaurs,
northern-hemisphere sauropods, and so forth, that had lost their smallest
members. I published this observation back in 1991 in the first printing of
_Mesozoic Meanderings_ #2, and it's likely not original with me (though I
have yet to find a prior reference).