While not quite as charismatic as those of dinosaurs, vegetable fossils can provide game-changing insight into modern plants and their evolutionary process. A team of scientists led by paleobotanist Peter Wilf of Penn State University discovered fossils of tomatillos, that delicious relative of the tomato that is a key ingredient in salsa verde, in the Patagonia region of Argentina. Using atomic age dating techniques, the team determined that the newly discovered primordial tomatillos are about 52-million years old, at least 12 million years older than previously thought.
Although the site where the fossils were found is now a cold and arid environment, the ancient tomatillos thrived in a very different climate. “The plants that generated these fossils were alive in a temperate rain forest next to a volcano,” said Richard Olmstead, an evolutionary biologist at the University of Washington. “When it finally snapped together [that] we were looking at a fossil tomatillo, it was quite shocking. It was disbelief. It was joy coupled with disbelief.” The tomatillo is a member of the nightshade family, which includes tomatoes, peppers, potatoes, eggplants, and tobacco. The recently discovered fossils are the most intact and earliest examples of nightshade to date. “It’s a tremendous find. It provides insight totally absent from the fossil record and our understanding of the family prior to this,” said Olmstead.
Wilf and his team have given the species name infinemundi, Latin for “at the end of the world,” to its tomatillo specimen in reference to both where it was discovered and the era in which it lived. “It’s a nod to the modern and ancient location,” said Wilf “It’s at the edge of Argentina, so the end of the world that way. And it’s at the end of this time in Earth history.” This ancient tomatillo would have lived on the edge of major geologic and climatic changes, including the rise of the Andes Mountains and the retreat of tropical biomes. These disruptions would have set the stage for the great diversity that emerged from the nightshade family, which includes over 2,400 extant species today.