Gigantic herbivores in the Americas vanished roughly 10,000 years ago, disrupting the long-range seed dispersal of sizable fleshy plant species. The Anachronistic hypothesis of the Neotropics, proposed in 1982, posits that large fruits evolved to attract these massive animals. While this idea accounts for several significant adaptations in “megafaunal fruit” plants, it lacks strong evidence. Recently, researchers from Chile, Spain, and Brazil uncovered fossil evidence of frugivory, pointing to the existence of the extinct South American species Notiomastodon platensis. Their findings indicate that the extinction of this species and its relatives heightens the risk of giant fruit plants becoming extinct in certain South American regions.
Diversity of extinct mammals inhabiting the environment of Lake Tagua, Chile. Image credit: Mauricio Alvarez.
“In 1982, biologist Daniel Jansen and paleontologist Paul Martin proposed groundbreaking ideas, suggesting that many tropical plants developed large, sweet, colorful fruits to attract large animals like mastodons, native horses, or giant herds,” said iphes-cerca and colleagues.
“The theory, known as the anachronism hypothesis of the Neotropics, has remained unverified for over four decades.”
“Our research provides direct fossil evidence to substantiate this concept.”
In this study, Dr. González-Gurda and co-authors examined 96 fossil teeth from the Pleistocene mastodon, Notiomastodon platensis.
These fossils were collected over a distance of more than 1,500 km, spanning from Los Bilo to Chiloe Island in southern Chile.
Nearly half of the specimens originated from well-known sites such as Lake Tagua, an ancient basin abundant with Pleistocene fauna located in the current O’Higgins region.
To understand the lifestyle of Notiomastodon platensis, various techniques were utilized including isotopic analysis, microscopic examination of dental wear, and fossil calculation analysis,” the authors stated.
“We discovered typical starch residues and plant tissues of fleshy fruits, including the Chilean palm (Jubaea chilensis),” added Professor Florent Rivals, a researcher at ICREA, Iphes-Cerca, and Rovira I Virgili University.
“This directly confirms that these animals regularly consumed fruit and contributed to reforestation.”
“Stable isotopic analysis enabled us to reconstruct the animal’s habitat and diet with high accuracy,” noted Dr. Ivan Ramirez Pedraza, a researcher at Ifes Serca and Rovira I-Vilgiri University.
“The data points to a forest ecosystem rich in fruit resources, where mastodons roamed across long distances, aiding in seed dispersal. Its ecological role remains pivotal.”
“Dental chemistry offers us a direct glimpse into the past,” commented Dr. Carlos Tornero, a researcher at Ifes Cerca and the Autonomous University of Barcelona.
“Combining various evidence allowed us to strongly affirm the critical role they played within these ecosystems.”
The researchers also employed machine learning models to assess the current conservation status of megafauna-dependent plants across different regions of South America.
Their findings are intriguing: in central Chile, 40% of these species currently face threats. This ratio is four times higher than that of tropical regions where animals like tapirs and monkeys continue to function as alternative seed dispersers.
“If the ecological connection between plants and animals is completely severed, the repercussions will be evident for thousands of years,” states ecosystem researcher Andrea Leuza.
Species like the Gomortega (Gomortega keule), the Chilean palm, and the Monkey Puzzle Tree (Araucaria araucana) are now surviving in small, fragmented populations with low genetic diversity.
“They are extinct interacting creatures.”
The survey results were published today in the journal Nature’s Ecology and Evolution.
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E. González-Guarda et al. Fossil evidence of material frugivory and its lasting impact on pre-American ecosystems. Nat Ecol Evol Published online on June 13th, 2025. doi:10.1038/s41559-025-02713-8
Source: www.sci.news
