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

If you’ve ever eaten a raisin or enjoyed a glass of wine, you may partly have the extinction of the dinosaurs to thank for it. In a discovery described in the journal Plants of nature, researchers found fossil grape seeds ranging from 60 to 19 million years old in Colombia, Panama and Peru. One of these species represents the earliest known example of plants from the grape family in the Western Hemisphere. These fossil seeds help show how the grape family spread in the years after the dinosaurs died out.

“These are the oldest grapes ever found in this part of the world and are several million years younger than the oldest ever found on the other side of the planet,” says Fabiany Herrera, an assistant curator of paleobotany at the. Field Museum at Chicago’s Negaunee Integrative Research Center and lead author of the paper. “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 fruits to be preserved as fossils, so scientists’ understanding of ancient fruits often comes from seeds, which are more likely to fossilize. The earliest 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—just as a large asteroid hit Earth, causing a mass extinction that changed the course of life on the planet.

“We always think about the animals, the dinosaurs, because they were the biggest things that were affected, but the extinction event also had a big impact on the plants,” Herrera says. “The forest restored itself, in a way that changed the composition of the plants.”

Herrera and his colleagues hypothesize that the extinction of the dinosaurs may have helped change the forests. “Large animals, such as dinosaurs, are known to change the ecosystems around them. We think that if there were large dinosaurs roaming the forest, they would likely have knocked down the trees, effectively keeping the forests more open. than they are today,” says Mónica Carvalho. , a co-author of the paper and assistant curator at the University of Michigan Museum of Paleontology.

But without the big dinosaurs to cut them down, some rainforests, including those in South America, became more crowded, with layers of trees forming a floor and a canopy.

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

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

“The grape has 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. “I have been searching for the oldest grape in the Western Hemisphere since I was a student.

But in 2022, Herrera and his co-author Mónica Carvalho were conducting fieldwork in the Colombian Andes when a fossil caught Carvalho’s eye. “She looked at me and said: ‘Fabiany, a grape!’ And then I looked at her, I said: ‘Oh my God.’ It was so exciting,” recalls Herrera. The fossil was in a 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 small, but Herrera and Carvalho were able to identify it based on its distinctive shape, size and other morphological features. Back at the lab, they ran CT scans showing her internal structure that confirmed her identity.

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

The team carried out further fieldwork in South and Central America, and in the journal Nature Plants, Herrera and his co-authors eventually described nine new species of fossil grapes from Colombia, Panama and Peru, dating from 60 to 19 million years ago. old. These fossilized seeds tell the story not only of the spread of the grape in the Western Hemisphere, but also of the many extinctions and dispersals the grape family has undergone.

Fossils are only distant relatives of native grapes in the Western Hemisphere, and some, like the two species of Leea, are found only in the Eastern Hemisphere today. Their places within the grape family tree indicate that their evolutionary journey has been turbulent.

“The fossil record tells us that grapes are a very resilient order. They are a group that has suffered a lot of extinction in the Central and South American region, but they also managed to adapt and survive in other parts of the world.” says Herrera.

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

This study was authored 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 (Museum of Nature in Florida History, University of Florida).