[Taxacom] Early angiosperms (and hymenopteran co-evolution)

[Kenneth Kinman]

Dear All,      
      Well, as far as Croizat is concerned, the value of his input on
this particular issue will ultimately rest on whether early angiosperms
evolved in very wet environments (mangroves) or rather dry, upland
environments.  He may have gotten the right answer for the wrong reason,
in which case he doesn't deserve the credit that should be given those
who got the right answer for the RIGHT reason.  We shall see.                           
       Either way, I strongly suspect that the drastic and widespread
nature of the end-Permian extinction had a profound effect in initiating
the beginnings of the rise of angiosperms over their gymnosperm
ancestors.  If so, their early Mesozoic proliferation is similar to (but
not quite as sudden as) the more rapid Cenozoic proliferation of mammals
and birds over their reptile ancestors following the end-Cretaceous
extinction.  But as has been noted, a restricted upland habitat of
Triassic (and/or earlier) angiosperms may have simply been unfavorable
to fossil preservation, although I am not sure this is quite as valid
for pollen preservation unless early angiosperms were very dependent on
insect pollination rather than more widespread pollination by wind
dispersal.         
      That is where the early co-evolution of angiosperms and certain
insect taxa becomes particularly relevant.  The evolution of Hymenoptera
in particular seems to be rather intimately associated with angiosperms
(and perhaps the wasps in particular, since they are the equivalent of
the "reptiles" of the hymenopterans).  Of course, this may have
initially been clouded by equally important interactions with early
beetles (or even forms intermediate between beetles and early
hymenopterans).
          ---------Ken Kinman