Taxacom: "Early Permian" angiosperms... real or not real taxa/names?

[Tony Rees]

Terribly sorry, Michael; indeed they were from John Grehan, my apologies...

Meanwhile in the light of John's (not Michael's!) comment "These
'hypothetical dates" are widely accepted as more than that - even as
empirical proof of age - by many, many, many people, including a number of
individuals on Taxacom. ... The suggestions do not come from 'molecular
evidence' but from fossils that
are used to calibrate divergence."

A further relevant paper is perhaps: S Magallón et al., 2013: "Land plant
evolutionary timeline: gene effects are secondary to fossil constraints in
relaxed clock estimation of age and substitution rates", Am J Bot . 2013
Mar;100(3):556-73. doi: 10.3732/ajb.1200416. In this the authors state: "
Among the nodes constrained in this study, the angiosperm crown node is
unique in that its estimated age is substantially older than the oldest
fossils that can be reliably assigned to the clade. ...  The age of the
angiosperm crown node has proved to be a particularly difficult estimation
problem. We think that their true age is older than but closer to the
fossil date than to the molecular clock estimates. The pattern of their
earliest appearance in the fossil record, with increasing distribution,
local abundance, and morphological diversity of angiosperm pollen and leaf
types in Early Cretaceous sediments; and the generally coinciding order of
appearance of lineages in stratigraphic sequences and in molecular
phylogenies, are formidable objections to the possibility of a long portion
of early angiosperm history missing in the fossil record."

So, the authors themselves (in this study) commenting that the "estimated
age" based on molecular models, far from being empirical proof of age, is
seeming less likely to be correct than one more closely approaching that
based on the known fossil evidence.

Regards - Tony


On Fri, 3 Jun 2022 at 17:54, Michael Heads <m.j.heads at gmail.com> wrote:

> Just a clarification - these comments were from John Grehan, not from me.
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