Paleobotanists have described nine new species of the grape family Vitaceae on the basis of 60- to 19-million-year-old fossil seeds discovered in four Neotropical paleofloras. These include Lithouva susmanii from Colombia, a new species that provides the earliest evidence of Vitaceae in the western hemisphere.
Lithouva susmanii from the Paleocene of Colombia. Scale bar- 1 mm. Image credit: Herrera et al., doi: 10.1038/s41477-024-01717-9.
It’s rare for soft tissues like fruits to be preserved as fossils, so scientists’ understanding of ancient fruits often comes from the seeds, which are more likely to fossilize.
The earliest known grape seed fossils were found in India and are 66 million years old.
“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,” said Dr. Fabiany Herrera, a paleobotanist at the Field Museum.
“The forest reset itself, in a way that changed the composition of the plants.”
Dr. Herrera and his colleagues hypothesize that the disappearance of the dinosaurs might have helped alter the forests.
“Large animals, such as dinosaurs, are known to alter their surrounding ecosystems,” said Dr. Mónica Carvalho, a paleobotanist at the University of Michigan’s Museum of Paleontology.
“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.”
“But without large dinosaurs to prune them, some tropical forests, including those in South America, became more crowded, with layers of trees forming an understory and a canopy.”
“These new, dense forests provided an opportunity. In the fossil record, we start to see more plants that use vines to climb up trees, like grapes, around this time,” Dr. Herrera said.
“The diversification of birds and mammals in the years following the mass extinction may have also aided grapes by spreading their seeds.”
The researchers examined the fossilized grape seeds from the 60-million-year-old Bogota Formation in Colombia, the 41-million-year-old Tonosi Formation in Panama, the 28-million-year-old Mancora Formation in western Peru, and the 19-million-year-old Cucaracha Formation that crop out in the Gaillard Cut of the Panama Canal.
They were able to identify at least nine new species of the grape family, including Lithouva susmanii, which provides the earliest evidence of grapes in the western hemisphere.
“This new species is important because it supports a South American origin of the group in which the common grape vine Vitis evolved,” said Dr. Gregory Stull, a paleobotanist at the National Museum of Natural History.
“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,” Dr. Herrera said.
“This discovery is important because it shows that after the extinction of the dinosaurs, grapes really started to spread across the world.”
The places of the new species within the grape family tree indicate that their evolutionary journey has been a tumultuous one.
“The fossil record tells us that grapes are a very resilient order,” Dr. Herrera said.
“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.”
“Given the mass extinction our planet is currently facing, studies like this one 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.”
The study was published in the journal Nature Plants.
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F. Herrera et al. Cenozoic seeds of Vitaceae reveal a deep history of extinction and dispersal in the Neotropics. Nat. Plants, published online July 1, 2024; doi: 10.1038/s41477-024-01717-9
Source : Breaking Science News