Newly discovered fossils in Argentina have revealed important information about the migration of spurge plants, including economically significant species like rubber trees and castor oil plants. These findings suggest that these plants migrated from southern South America to southeast Asia and other regions due to changes in climate and geography.
Research led by Penn State University indicates that a group of spurges belonging to the Macaranga-Mallotus clade (MMC) may have originated in South America during the time when it was still part of the supercontinent Gondwana. The study challenges the prevailing idea that the MMC evolved in Asia. It provides the first direct fossil evidence of spurges in Gondwanan South America.
The spurge family, known as Euphorbiaceae, is well adapted to various environments and is prevalent in tropical rainforests around the world, especially in Africa and Asia. The family comprises over 6,000 species, with around 400 species in the MMC alone. Until now, the MMC has been considered an “Old World” plant group with Asian origins, but this new study suggests “New World” origins for MMC spurges.
The newly discovered fossils, estimated to be 52 million years old, were found in Argentina. They provide valuable insights into environmental changes, plate tectonics, and biogeography. It is believed that these plants originated and evolved in Gondwana but retreated as the climate became drier and colder. Eventually, they found refuge in Australia.
The movement of tectonic plates led to the separation of Australia from Antarctica and its collision with southeast Asia. This collision allowed the spurge plants to reach New Guinea and the southeast Asian rainforest, where they are now commonly found.
The discovery of these fossils serves as a warning about the resilience of the natural world but also highlights the current threats it faces due to deforestation and environmental changes. The study emphasizes the need to protect these plants and their habitats.
The research was funded by the National Science Foundation and the National Geographic Society, further illustrating the importance and support given to such scientific studies. These findings contribute to our understanding of plant evolution and migration, shedding light on the intricate connections between climate, geography, and the natural world.