Researchers from Penn State University have discovered ancient, 52-million-year-old fruit fossils that show nightshades evolved much earlier than previously thought, a new study published in the journal Science reports.
Nighshades are a large class of plants that includes tomatoes, peppers, tobacco, garden flowers, and medicinal plants. While all of those are quite common, their early history is largely unknown. That is because only a few fossilized samples have ever been found, making it hard to create a solid fossil record. This new study shows the group dates back tens of millions of years.
Researchers discovered the fossils in a fossilized rainforest in Patagonia. The species is a type of Physalis and is the first ancient nightshade fossil ever found.
The fruit is a berry that is closely related to both tomatillos and ground cherries, two species that have paper-like husks growing around fleshy fruit. Before this study, it was thought that the fruits evolved around the time the Andes were formed. However, the new fossils reveal they are much older.
“A lot of the evolutionary history of life, especially plants, which are rare as fossils, is largely unknown,” said lead author Peter Wilf, a professor of geosciences at Pennsylvania State University, according to BBC News. “Here we have this discovery of these incredibly rare, delicate fossils – here you have a berry surrounded by this papery calyx – it’s almost unheard of that such a thing could be fossilized.”
The study also shows a rare link from the late-Gondwanan Patagonian to living New World plants, which gives credence to the idea that there once was an overland connection stretching from South America to Australia through Antarctica.
The discovery suggests that more nightshade fossils may be found at other southern locations. To investigate this, the team plans to continue its search across South America to see what other specimens can be found.
“These fossils are one of a kind…Our fossils show that the evolutionary history of this plant family is much older than previously considered, particularly in South America, and they unveil important implications for understanding the diversification of the family,” said study co-author Mónica Carvalho, a former Ph.D. student at Penn State.