[Taxacom] Angiosperm origins: Darwin's "abominable" mystery

[Kenneth Kinman]

Dear All,
      No wonder Charles Darwin regarded the origin of angiosperms as an
"abominable mystery".  Even today we are hard pressed to pin it down,
and the early fossil record before the Cretaceous remains sketchy at
best.
       However, new molecular evidence published in Proceedings of the
National Academy of Sciences earlier this week indicates that even the
crown clade of angiosperms may have originated as early as the Upper
Triassic.  This most likely indicates that stem angiosperms (which went
extinct) occur earlier.  I don't yet have access to the article, but you
can at least read the abstract here:

http://www.pnas.org/content/early/2010/03/15/1001225107 

       So were the earliest angiosperms just earlier in the Triassic, or
back in the Paleozoic as some evidence seems to suggest?   There is
tantalizing evidence that they may have split off from gymnosperms in
the Permian or even the late Carboniferous.  There is not only direct
trace evidence of fossil biomolecules in the Permian, but also indirect
genetic evidence (the split between paleo AP3 and PI genes) which date
angiosperm origins to the Permian or slightly before.  Whether
gigantopterids (and/or Bennettitales) might be immediate sister groups
of the angiosperms remains to be seen.  However, both those groups are
extremely interesting in both their timing and morphology as possible
gymnosperm sister groups to angiosperms (Phylum Magnoliophyta).
          -----------Ken Kinman