The extinction of dinosaurs is partly due to the spread of grapes on our planet, a team of researchers said.
In a discovery described in the journal Nature Plants, researchers identified nine new species of fossil grapes, ranging in age from 60 to 19 million years old. The seeds were discovered in Colombia, Panama and Peru.
One of these species represents the oldest known example of grapevines in the Western Hemisphere. These fossil seeds help show how the grapevine spread in the years after the dinosaurs went extinct.
“These are the oldest grapes ever found in this part of the world, and they are a few million years younger than the oldest grapes found on the other side of the planet,” says Fabiani Herrera, assistant curator of paleobotany at the Field Museum at the Negaunee Center for Integrative Research in Chicago and lead author of the paper. “This discovery is important because it shows that after the dinosaurs went extinct, grapes were already beginning to spread around the world.”
Soft tissues such as fruits are rarely preserved as fossils, so scientists' understanding of ancient fruits often comes from seeds, which are more likely to turn into fossils.
In fact, the oldest known grape seed fossil was found in India in 2013, and is 66 million years old. It turns out that this tiny fossil was not only the first grape fossil in South America, but also one of the oldest in the world. This was confirmed with the help of CT scans.
In the new study, ongoing fieldwork by researchers in South and Central America has led to the discovery of nine new fossil grape species. These ancient seeds chronicle the migration of the grape family across the Western Hemisphere amid a series of extinctions and dispersals.
“We always think about animals, and dinosaurs, because they were the biggest ones affected, but the extinction event had a big impact on plants as well,” Herrera says. “The forest reset itself in a way that changed the composition of the plants.”
Herrera and his colleagues hypothesize that the disappearance of dinosaurs may have helped change the forests, creating a more suitable environment for grapes.
“Large animals, like dinosaurs, are known to alter the ecosystems around them,” explains Monica Carvalho, co-author of the paper and assistant curator at the University of Michigan Museum of Paleontology. “We think that if there were large dinosaurs roaming the forest, they were likely to be cutting down trees, making the forests more open than they are today. But without large dinosaurs to prune them, some tropical forests, including those in South America, became more crowded.”
"In the fossil record, we start to see more plants that use vines to climb trees, like grapes, around this time," Herrera said.
The study throws in a side note: The diversity of birds and mammals after the dinosaurs' extinction may have also helped grapes by spreading their seeds.
Magnificent finding!
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