[Taxacom] fossil potato relative

[Scott Thomson]

I have to say also I find the reliance on molecular dates in recent times
disturbing. I have seen dates for groups of 23 mya, 35 mya, and 52 mya (3
separate published papers) on a group that had an actual fossil, a good
one, that was well dated to over 100 mya. I also find the assumptions of
molecular dates to be rather daring ones and a bit disturbing when I
realise that in many cases the fossils used to calibrate such tests are
obtained by obtaining info from a quick perusal of Fossilworks. I take
molecular dates with a grain of salt.

Cheers Scott

On Thu, Jun 14, 2018 at 8:54 PM, John Grehan <calabar.john at gmail.com> wrote:

> Probably just being polite :)
>
> Here is what they said in their article. Note the first sentence in
> particular.
>
> "Our results reinforce the emerging pattern
> wherein numerous fossil plant taxa from Gondwanan
> Patagonia and Antarctica are substantially
> older than their corresponding molecular
> dates (26, 27), demonstrating Gondwanan history
> for groups conjectured to have post-Gondwanan
> origins under entirely different paleogeographic
> and paleoclimatic scenarios. Likewise, the derived
> position of the newly identified fossil species
> shows that the origins and diversification
> of Solanaceae must have taken place at a much
> earlier time than previously thought, considerably
> before final Gondwanan breakup. Other
> regions of Gondwana are also likely to have
> played prominent roles in Solanaceae evolution,
> especially Antarctica, which has produced
> other important asterid fossils (27). Moreover,
> the newly identified fossils directly help to
> resolve temporal inconsistencies between the
> evolutionary timing of Solanaceae and its herbivores
> and mutualists (28). The large fossil
> berry strongly implicates trophic associations
> with animals, as seen in extant Physalis (29).
> Today, Physalis inhabits South, Central, and
> North America, and Mexico is its center of diversity
> (2). Thus, the fossils establish a rare link
> to extant New World floras from late-Gondwanan
> Patagonian assemblages, whose living relatives
> are mostly concentrated in the Old World tropics
> and subtropics."
>
> On Thu, Jun 14, 2018 at 8:21 PM, David Campbell <pleuronaia at gmail.com>
> wrote:
>
> > "The fossils underpin the need for researchers to be careful"
> >
> > Why not conclude "the fossils show that the molecular clock dates were
> > wrong"?  Calibration, calculation, and interpretation of molecular clocks
> > all have serious problems - why use them?
> >
> > On Thu, Jun 14, 2018 at 1:52 PM, John Grehan <calabar.john at gmail.com>
> > wrote:
> >
> > > Not making any judgement about this one, but notice comment on
> molecular
> > > clocks at the end.
> > >
> > > John Grehan
> > >
> > > http://www.iflscience.com/plants-and-animals/52millionyearold-fossil-
> > > relative-to-the-potato-discovered-in-patagonia/
> > >
> > > Despite becoming ubiquitous in almost every corner of the world,
> > > surprisingly little is known about the deep evolutionary history of the
> > > group of plants that gave rise to potatoes, tomatoes, and tobacco.
> > > Now, researchers
> > > have found
> > > <http://phys.org/news/2017-01-south-american-fossil-
> > > tomatillos-nightshades.html>
> > >  just how far back these organisms go, with the discovery of a fossil
> > > relative that dates back to 52 million years ago, tens of millions of
> > years
> > > older than previously thought.
> > >
> > > The fossil belongs to a fragile berry of a plant known as a tomatillo,
> or
> > > ground cherry. They form fruit that is often surrounded by a thin,
> papery
> > > lantern, making it difficult for them to be fossilized
> > > <http://www.bbc.co.uk/news/science-environment-38511034>. Members of
> the
> > > *Physalis* genus, they form a small branch of the nightshade family,
> > which
> > > in turn includes many commercially important crops, from potatoes
> > > and petunias to chillies and aubergines.
> > >
> > > The only fossil fruits ever found from this family of almost 2,000
> > species
> > > of plants, the two specimens were discovered in a fossilized rainforest
> > > that once grew across Patagonia in South America. With a lack of
> > available
> > > fossils for this group of plants, researchers have had to rely on
> > molecular
> > > dates for when the nightshade plants first evolved, and had settled on
> > the
> > > figure of around 35 to 51 million years old, while the tomatillo was
> > > thought to be a relative newcomer at only 10 million years old.
> > >
> > > This new discovery, however, completely changes this. The fossils,
> dating
> > > to 52 million years ago, show that the ground cherries are actually a
> > > relatively ancient branch of the nightshade family. “We exhaustively
> > > analyzed every detail of these fossils in comparison with all potential
> > > living relatives and there is no question that they represent the
> world's
> > > first physalis fossils and the first fossil fruits of the nightshade
> > > family,” says
> > > <http://phys.org/news/2017-01-south-american-fossil-
> > > tomatillos-nightshades.html>
> > >  Professor Peter Wilf, from Pennsylvania State University.
> > >
> > > The fossils underpin the need for researchers to be careful when
> deducing
> > > an organism's evolutionary age solely from molecular clocks.
> > > _______________________________________________
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> > >
> > > Nurturing Nuance while Assaulting Ambiguity for 31 Some Years,
> 1987-2018.
> > >
> >
> >
> >
> > --
> > Dr. David Campbell
> > Associate Professor, Geology
> > Department of Natural Sciences
> > Box 7270
> > Gardner-Webb University
> > Boiling Springs NC 28017
> > _______________________________________________
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> >
> > Nurturing Nuance while Assaulting Ambiguity for 31 Some Years, 1987-2018.
> >
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> Nurturing Nuance while Assaulting Ambiguity for 31 Some Years, 1987-2018.
>



-- 
Scott Thomson
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