![]() ![]() The scientists studied the detailed characteristics of the leaves and fruits and compared them with living specimens. ![]() Dating of volcanic rocks at this site places the fossils at 52 million years old, a globally warm time immediately preceding the final separation of Gondwana. The fossils came from a site in Chubut, Argentina called Laguna del Hunco, where the researchers have collected fossils for decades. Wilf and his colleagues at Argentina’s Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET) in Bariloche and the Museo Paleontológico Egidio Feruglio (MEF), and Cornell University examined 11 leaf fossils and two compound infructescence fossils, or fossils that show preserved fruits and seeds attached to branches. The current study, based on fossils more than twice as old as the New Zealand specimens, provides the first evidence of “New World” origins for MMC spurges and adds two new species to the plant family, according to the scientists.įossil leaves with characteristics identical to several Macaranga species. Given their prevalence in southeast Asia and 23-million-year-old fossils previously found in New Zealand, scientists have considered the MMC an “Old World” plant group likely with Asian origins. ![]() ![]() The spurge family comprises more than 6,000 species, found mostly in the tropics but also in deserts and cold temperate zones, and there are about 400 species in the MMC alone. Its plants often have large, umbrella-like leaves that provide abundant shade, and they provide nutritious seeds for animal forage.” The MMC is well known in the Asian tropics and is highly visible along roadsides and in burned areas. “They make up much of the understory habitat that is structurally important to the rainforest and its animal life. “They’re common in tropical rainforests in Africa, South America, and most notably in Asia, where if you count the number of trees in a plot, they’re usually the second most common type,” he said. Altogether it is the most dramatic evolutionary biogeography story I’ve ever seen.”Īccording to Wilf, Euphorbiaceae have adapted well to evolutionary challenges in different environments. We’ve seen this pattern in many other plant groups we’ve found as fossils in South America like kauris, Asian chinkapin, and yellowwood trees. You can’t go much farther than that without leaving the planet. “But if they evolved in Asia, how in the world would they have gotten to where we found them, in Argentine rocks 50 million years old? Instead, we think these spurges tracked the moving continents from South America to Asia, to the other side of the world. “Our study provides the first direct fossil evidence of spurges in Gondwanan South America,” said Peter Wilf, professor of geosciences at Penn State and lead author of the current study, noting that the finding contrasts with the prevailing idea that the MMC evolved in Asia. The CT scan picked up density changes in the rock and rendered them into three-dimensional images. Prompted by shifts in climate and terrestrial movements over countless millennia, a group of spurges migrated thousands of miles away from ancient South America, reaching as far as Australia, Asia, and certain regions in Africa, according to research led by Penn State.Ī CT scan of a fossil infructescence showing fruits and tiny paired seeds inside the fruits. Now, recently identified fossils in Argentina indicate that these spurges embarked on their own journey several millions of years ago. The spurge family, also known as Euphorbiaceae, encompasses economically significant plants such as the rubber tree, castor oil plant, poinsettia, and cassava. Those who have embarked on extended journeys by road or bicycle have likely benefitted from a product of the spurge plant family – rubber. Newly discovered fossils in Argentina provide evidence that changes in climate and geography may have compelled a well-known species of spurge plants to migrate from southern South America to southeast Asia and beyond. The 52-million-year-old fossil fruits and leaves that the researchers identified as belonging the the Macaranga-Mallotus clade (MMC) of the spurge family suggest that the MMC, long considered to have Asian origins, may have first appeared in Gondwanan South America before spreading around the globe. A compound infructescence fossil showing preserved fruits and seeds attached to branches. ![]()
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