Sixty-million-year-old grape seeds reveal how the death of the dinosaurs may have paved the way for the spread of grapes

If you’ve ever snacked on a raisin or enjoyed a glass of wine, the extinction of the dinosaurs may be partly to blame. In a discovery described in the journal Natural plants, researchers have found fossil grape seeds that are 60 to 19 million years old in Colombia, Panama, and Peru. One of these species represents the oldest known example of a grape family in the Western Hemisphere. These fossil seeds help show how the grape family expanded in the years following the death of the dinosaurs.

“These are the oldest grapes ever found in this part of the world, and they’re several million years younger than the oldest ever found on the other side of the planet,” says Fabiany Herrera, assistant curator of paleobotany at the Field Museum of Negaunee Integrative Research Center in Chicago and lead author of the article. “This discovery is important because it shows that after the extinction of the dinosaurs, grapes really began to spread around the world.”

It’s rare for soft tissues like fruit to be preserved as fossils, so scientists understand ancient fruit often from seeds, which are more likely to have fossilized. The oldest known grape seed fossils were found in India and are 66 million years old. It’s no coincidence that grapes appeared in the fossil record 66 million years ago—that’s about the time a huge asteroid hit Earth and triggered a mass extinction event that changed the course of life on the planet.

“We always think about the animals, the dinosaurs, because those were the biggest things that could have been affected, but the extinction event had a huge impact on the plants as well,” Herrera says. “The forest reset in a way that changed the composition of the plants.”

Herrera and his colleagues hypothesize that the disappearance of the dinosaurs may have helped change the forests. “Large animals like dinosaurs are known to change their surrounding ecosystems. We think that if large dinosaurs were running through the forest, they probably would have cut down the trees, effectively keeping the forests more open than they are today,” says Mónica Carvalho, co-author article and associate curator at the University of Michigan Museum of Paleontology.

But without large dinosaurs to cut through them, some tropical forests, including those in South America, were more crowded, with layers of trees forming an understory and canopy.

These new, dense forests provided an opportunity. “In the fossil record around this time, we start to see more plants that use vines to climb trees, like grapes,” says Herrera. The diversification of birds and mammals in the years after the mass extinction may have also helped grapes by dispersing their seeds.

In 2013, Herrera received his Ph.D. advisor and lead author of the new paper, Steven Manchester, published a paper describing the oldest known grape seed fossil from India. While no fossil grapes have ever been found in South America, Herrera suspected they might be there too.

“Grapes have an extensive fossil record that starts about 50 million years ago, so I wanted to discover one in South America, but it was like looking for a needle in a haystack,” says Herrera. “Even as a student, I was looking for the oldest grapes in the Western Hemisphere.”

However, in 2022, Herrera and co-author Mónica Carvalho were doing fieldwork in the Colombian Andes when a fossil caught Carvalho’s eye. “She looked at me and said, ‘Fabians, crap!’ And then I looked at it, I was like, “Oh my God.” It was so exciting,” Herrera recalls. The fossil was in 60-million-year-old rock, making it not only the first South American grape fossil, but also among the oldest grape fossils in the world.

The fossil seed itself is tiny, but Herrera and Carvalho were able to identify it based on its specific shape, size and other morphological features. Back at the lab, they performed CT scans showing his internal structure, which confirmed his identity.

The team named the fossil Lithouva susmanii, “Susman’s stone grape,” in honor of Arthur T. Susman, a proponent of South American paleobotany at the Field Museum. “This new species is also important because it supports a South American origin for the group in which the Vitis vine evolved,” says co-author Gregory Stull of the National Museum of Natural History.

The team conducted additional fieldwork in South and Central America, and in the Nature Plants paper, Herrera and his coauthors eventually described nine new species of fossil grapes from Colombia, Panama, and Peru that are between 60 and 19 million years old. These fossilized seeds tell the story not only of the grape’s spread throughout the Western Hemisphere, but also of the many extinctions and dispersals the grape family went through.

Fossils are only distant relatives of grapes native to the Western Hemisphere, and a few, such as the two species of Leea, are found today only in the Eastern Hemisphere. Their places in the grape family tree suggest that their evolutionary path has been a tumultuous one.

“The fossil record tells us that grapes are a very resilient order. It is a group that has suffered many extinctions in the Central and South American region, but has also been able to adapt and survive in other parts of the world,” he added. says Herrera.

Given the mass extinctions our planet is currently facing, Herrera says studies like this are valuable because they reveal patterns about how biodiversity crises play out. “But the other thing I like about these fossils is that these little tiny, humble seeds can tell us so much about the evolution of the forest,” says Herrera.

This study was written by Fabiany Herrera (Field Museum), Mónica Carvalho (University of Michigan), Gregory Stull (National Museum of Natural History, Smithsonian Institution), Carlos Jarramillo (Smithsonian Tropical Research Institute) and Steven Manchester (Florida Museum of Natural History, University of Florida).