Taxacom: Extent angiosperm family in the Permian

[John Grehan]

Panbiogeographers often get a lot of flak and ridicule for tectonic
correlations that are much older than the oldest fossil or molecular so
called means and confidence limits. Well, here's an interesting input. Shi
et al 2022 "Fire-prone Rhamnaceae with South African affinities in
Cretaceous Myanmar amber" states:

"We report the discovery of two exquisitely preserved fossil flower
species, one identical to the inflorescences of the extant crown-eudicot
Shi et al 2022. Fire-prone Rhamnaceae with South African affinities in
Cretaceous Myanmar amber"..."genus Phylica and the other recovered as a
sister group to Phylica, both preserved as inclusions together with burned
plant remains in Cretaceous amber from northern Myanmar (~99 million years
ago). These specialized flower species, named Phylica piloburmensis sp.
nov. and Eophylica priscastellata gen. et sp. nov., exhibit traits
identical to those of modern taxa...110–99 Ma for Eophylica priscastellata
and 99 Ma for Phylica piloburmensis"

"The unique floral architecture preserved in Eophylica and Phylica fossils
is identical to that seen in extant members of the genus Phylica, predating
molecular clock estimates for the genus by at least 35 Myr"

The we have He & Lamont 2022 "Ancient Rhamnaceae flowers impute an origin
for flowering plants exceeding 250-million-years ago"

"Setting the molecular clock to newly described 100-million-year-old
flowering shoots of Phylica in Burmese amber enabled us to recalibrate the
phylogenetic history of Rhamnaceae.We traced its origin to 260 million
years ago (Ma) that can explain its migration within and beyond Gondwana
since that time and implies an origin for flowering plants that stretches
well beyond 290 Ma."

"The difference in estimated dates between the most recently produced
chronograms and that described here, using these new fossils, is profound.
Ignoring the minor error terms in each, previous results are an order of
magnitude lower for the origin of both Phylica and Phylicieae – the new
chronogram adds almost 100 My to their ages, as Phylica was previously
dated at 12–24 Ma"

". The effect on the estimated age of Rhamnaceae is even more remarkable:
it is in the order of 150 My compared with that previously reported, 74–103
M"

". Any past statistical concerns about large levels of uncertainty
surrounding the means pale into insignificance compared with the effect of
the ad hoc presence/absence of fossils used to set the molecular clock, as
shown here."

So - once again new evidence points not in the direction of 'recent'
origins, but extant angiosperm families in at least Permo-Triassic times.
Croizat was ridiculed for his predictions of early origins for modern
angiosperm families and even genera, but evidently this ridicule may be
somewhat premature.

John Grehan
-- 
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