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

[Michael Heads]

Magallon's estimate is highly conservative (i.e. very young, in line with
the textbook view of the 1960s). Here is a summary from a paper in prep.: .

The age of crown-group angiosperms has been estimated as: Earliest
Cretaceous (Magallon et al., 2015), Jurassic-Triassic (Foster and Ho, 2017;
Murat et al., 2017; Ramírez-Barahona et al., 2020; Nie et al., 2020;
Silvestro et al., 2021); Jurassic – Permian (Li et al., 2019); Lower
Jurassic – Triassic (Morris et al., 2018); Triassic (Barba-Montoya et al.,
2018); Triassic to Late Permian (Beaulieu et al., 2015); Triassic-Permian
(Zhang et al., 2020); Triassic-Carboniferous (Salomo et al., 2017), and
Permian (Yang et al., 2020). (For some reason, current studies, such as
these, equate the age of origin of crown angiosperms with the age of the
first divergence *within* the group, thus these dates are minimum ages
only).

On Fri, Jun 3, 2022 at 8:06 PM Tony Rees <tonyrees49 at gmail.com> wrote:

> 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.
>>
>>
>>

-- 
Dunedin, New Zealand.

My books:

*Biogeography and evolution in New Zealand. *Taylor and Francis/CRC, Boca
Raton FL. 2017.
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*Biogeography of Australasia:  A molecular analysis*. Cambridge University
Press, Cambridge. 2014. https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.cambridge.org%2F9781107041028&data=05%7C01%7Ctaxacom%40lists.ku.edu%7Cd45e8ff7969545b1b15008da453aee40%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C637898416664783485%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=PP8kac9IrpJKF3BVDtccva957jmDszp1NAOT8OudQZU%3D&reserved=0


*Molecular panbiogeography of the tropics. *University of California Press,
Berkeley. 2012. https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ucpress.edu%2Fbook.php%3Fisbn%3D9780520271968&data=05%7C01%7Ctaxacom%40lists.ku.edu%7Cd45e8ff7969545b1b15008da453aee40%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C637898416664783485%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=hU5SrOYJY1KrJwbKa0J5WOz2F0FHQy3p234KVJzpH5g%3D&reserved=0


*Panbiogeography: Tracking the history of life*. Oxford University Press,
New York. 1999. (With R. Craw and J. Grehan).
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