[Taxacom] fossil potato relative

[David Campbell]

"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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>



-- 
Dr. David Campbell
Associate Professor, Geology
Department of Natural Sciences
Box 7270
Gardner-Webb University
Boiling Springs NC 28017