A newly published study led by scientists from the Field Museum in Chicago (USA) includes descriptions of nine new species of fossil grapes.  The paper, published in the journal “Nature Plants” reveals how the extinction of the non-avian dinosaurs may have permitted grape vines to spread and diversify.  Some of the newly described grape taxa are the oldest found to date in the Western Hemisphere.  The fossils were found in Peru, Panama and Columbia and range in age from sixty million years old to around nineteen million years old.  The seeds range in geological age from the Palaeocene Epoch to the Miocene Epoch.

Fossil grape (photograph top left) with computer model generated from CT fossil scans (top right). Line drawings illustrating the fossil by Pollyanna von Knorring (below). Picture credit: Fabiany Herrera.

Picture credit: Fabiany Herrera

Studying Fossil Grapes

These fossil seeds from Central and South America help to show how the grape family (Vitis) spread in the years following the extinction of the dinosaurs.

Lead author of the paper Fabiany Herrera (assistant curator of palaeobotany at the Field Museum in Chicago), commented:

“These are the oldest grapes ever found in this part of the world, and they’re a few million years younger than the oldest ones ever found on the other side of the planet.  This discovery is important because it shows that after the extinction of the dinosaurs, grapes really started to spread across the world.”

It is rare for fruits to be preserved in the fossil record.  However, seeds are more likely to survive the fossilisation process.  What palaeobotanists know about the evolution of angiosperms has been greatly enhanced by studying seeds and fossil pollen.  The earliest known grape seed fossils were found in India.  They are approximately sixty-six million years old.  At this time, there was a global extinction event.  This extinction was probably caused by the impact of an extra-terrestrial bolide.  This devastated life on Earth and led to a re-setting of ecosystems.  The composition of forests was altered as the extinction event affected both fauna and flora.

Fabiany Herrera in the field holding a grape fossil. Picture credit: Fabiany Herrera.

Picture credit: Fabiany Herrera

Dinosaur Extinction Helped Grape Growers

Herrera and his colleagues postulate that the extinction of the Dinosauria helped alter the flora within forests.

Co-author Mónica Carvalho explained:

“Large animals, such as dinosaurs, are known to alter their surrounding ecosystems. We think that if there were large dinosaurs roaming through the forest, they were likely knocking down trees, effectively maintaining forests more open than they are today.”

With the dinosaurs having died out and the absence of large mammals during the Palaeocene, forests became more crowded.  There were no large animals present to deplete the forest understorey and create a more open environment.  These new, dense forests provided an opportunity for plants like vines to become more widespread.  Ultimately, modern-day wine producers might have to thank dinosaurs for the evolution of the grape family of plants.

The diversification of mammals and birds may also have aided the spread of vines by helping to spread their seeds.

The Significance and Importance of Fossil Grapes

In 2013, Herrera’s PhD advisor and senior author of the new paper, Steven Manchester, published the paper describing the oldest known grape seed fossil from India.  Herrera suspected that ancient grape vines existed in South America too.

Herrera commented:

“Grapes have an extensive fossil record that starts about fifty million years ago.  I wanted to discover one in South America, but it was like looking for a needle in a haystack.  I’ve been looking for the oldest grape in the Western Hemisphere since I was an undergraduate student.”

Field work in the Colombian Andes with study co-author Mónica Carvalho provided the breakthrough.  Mónica discovered a fossilised grape seed.  The specimen was at least sixty million years old.  It was the first grape fossil to be found in South America.

Mónica Carvalho excitedly holding a grape fossil. Picture credit: Fabiany Herrera.

Picture credit: Fabiany Herrera

A Tiny Fossil Seed

The fossil seed is extremely small. However, Herrera and Carvalho were able to identify it based on its particular shape, size, and other morphological features. CT scans were undertaken to examine the fossil’s internal structure and confirm its affinity with the grape family.  This new taxon was named Lithouva susmanii.  The binomial name translates as “Susman’s stone grape”.  The name honours Arther T. Susman a supporter of South American palaeobotany at the Field Museum.

Co-author Gregory Stull of the National Museum of Natural History (Washington DC) explained the significance of these fossil grapes:

 “This new species is also important because it supports a South American origin of the group in which the common grape vine Vitis evolved.”

The field studies in Central and South America led to the scientific description of nine new species of fossil grapes.  These fossilised seeds not only tell the story of grapes’ spread across the Western Hemisphere, but also of the many extinctions and dispersals the grape family has undergone. The fossils are only distant relatives of the grapes native to the Western Hemisphere and a few, like the two species of Leea identified are only found in the Eastern Hemisphere today.

A Tumultuous Evolutionary Journey

These fossils suggest that the evolutionary journey of the grape family has been tumultuous.  Herrera commented that the fossil record of grapes demonstrates that these plants are extremely resilient.

Given the mass extinction our planet is currently facing, Herrera commented that studies like this one are valuable because they reveal patterns about how biodiversity crises play out.

Everything Dinosaur acknowledges the assistance of a media release from the Field Museum (Chicago) in the compilation of this article.

The scientific paper: “Cenozoic seeds of Vitaceae reveal a deep history of extinction and dispersal in the Neotropics” by Fabiany Herrera, Mónica R. Carvalho, Gregory W. Stull, Carlos Jaramillo and Steven R. Manchester published in Nature Plants.

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