Evrim Yazgin
Cosmos science journalist
Scientists have found a surprising connection between dinosaurs and ancient grapes.
Fossilised seeds found in Central and South America hint that the mass extinction at the end of the “Age of Dinosaurs” might have created the conditions for ancient grapes to spread.
Analyses of fossil grape seeds from 19 million up to 60 million years ago are detailed in a study published in the journal Nature Plants. The fossils were found in Colombia, Panama and Peru. One of the grape seeds is the earliest known example of a species in the grape family found in the western hemisphere.
“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,” says lead author Fabiany Herrera from Chicago’s Negaunee Integrative Research Center.
“After the extinction of the dinosaurs, grapes really started to spread across the world.”
Soft parts of fruits rarely fossilise. Palaeobotanists have to rely on their seeds, which are far more likely to fossilise, to study ancient fruits.
The oldest known fossil grape seeds were found in India and date to 66 million years ago – precisely around the time a giant asteroid crashed into Earth triggering the demise of the non-avian dinosaurs in a mass extinction event which spelled the end for three-quarters of plant and animal species.
“We always think about the animals, the dinosaurs, because they were the biggest things to be affected, but the extinction event had a huge impact on plants too,” says Herrera. “The forest reset itself in a way that changed the composition of the plants.”
Herrera’s team believe the disappearance of the large dinosaurs had a lasting effect on forests.
“Large animals, such as dinosaurs, are known to alter their surrounding ecosystems,” says co-author Mónica Carvalho, assistant curator at the University of Michigan’s Museum of Palaeontology. “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.”
After large dinosaur species went extinct, forests became more dense.
“In the fossil record, we start to see more plants that use vines to climb up trees, like grapes, around this time,” says Herrera.
In addition, after the mass extinction there was a diversification of birds and mammals which may also have aided grapes and other fruiting plants to spread their seeds.
Scientists had previously never found fossil grapes in South America. Herrera’s team found their 60-million-year-old seed in the Colombian Andes. They confirmed its identity using CT scans which showed the tell-tale grape-like internal structure.
They named the ancient South American grape species Lithouva susmanii.
“This new species is also important because it supports a South American origin of the group in which the common grape vine Vitis evolved,” says co-author Gregory Stull of the Smithsonian’s National Museum of Natural History.
“The fossil record tells us that grapes are a very resilient order,” Herrera says. “They’re 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.”
As we live through another mass extinction, the team says the study helps understand the ways in which biodiversity crises play out.
“These little tiny, humble seeds can tell us so much about the evolution of the forest,” Hererra says.
