An amazing discovery was made in a volcanic lake in Patagonia, Argentina. Fossilized fruits dating back 52 million years were found at the Laguna del Junco, a volcanic lake known as a great source of fossils. The fruits are incredibly well preserved.
The fossils have been identified as a kind of berries similar to Physalis (ground cherries). These are lantern fruits of the Solanaceae family (or the nightshade). Other plants belonging to the nightshades are tomatoes, potatoes, peppers, and tobacco, plants with a rich economic and cultural importance.
This discovery provides more information on the family of plants the fossils belong to. It was formerly believed that the diversification of this family of plants took place in South America during the separation from the Gondwana supercontinent (30 million years ago). The hypothesis was not proven due to the lack of fossil probes.
After the discovery, scientists found out that the nightshade family was already diversified at the moment of the separation of the continents. They also found that the fossils are part of a late-evolving branch dating back to the moment when South America was adjacent to Antarctica, before the separation.
The fossils are in an outstanding condition. The outer skin is intact and the berry is still visible inside the fruit. Peter Wilf, professor of geosciences at Pennsylvania State University, said that, although it encompasses over 2,000 species, these are the only fossils ever found pertaining to this family of plants. He was also amazed that a plant could have been fossilized in such a state, with its calyx and berry intact.
Laguna del Junco, the lake that kept the fossils, is volcanic and the acidic properties of the water make possible the hosting and good preservation of fossils. The acids kept the fruits in a sort of protective capsule that prevented the microbes from breaking them down. The fruits are also thought to have been covered with layer after layer of sediments on the bottom of the lake and so they were pressed flat.
Researchers are now on the lookout for more fossilized fruits of the kind, both in Argentina and in Antarctica. Their goal is to find out more on the history of the Solanaceae family and reshape what we know about plants.
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