Most megafaunal herbivores in the Americas disappeared approximately 10,000 years ago, probably disturbing the dispersion of long distance seeds of large fruits and fleshy plant species. Proposed in 1982, the hypothesis of neotropical anachronism suggests that large fruits have evolved to attract the megafauna now extinct. Although this explains many key adaptations of “megafaunal fruits” plants, it lacks solid evidence. In new research, researchers from Chile, Spain and Brazil have discovered fossil evidence of frugivory in a South American promptoscidian extinguished Notiomastodon plansisAnd noted that the disappearance of this animal and its relatives increased the risks of extinction for megafaunal fruit plants in the regions of South America.
Diversity of extinct mammals that lived in the Tagua tagua lake environment, Chile. Image credit: Mauricio Álvarez.
“In 1982, Biologist Daniel Janzen and Paleontologist Paul Martin proposed to Revolutionary Idea: Many Tropical Plants Developed Large, Sweet, and Colorful Fruits to Attract Large Animals – Such as Mastodons, Native Horses, Or Giant Ground Sloths – That Would Serve As Seed Dispersers,” Said Dr. Erwin González-Guarda, a paleontologist at the University of O’Higgins and Iphs-Carca, and his colleagues.
“Known as the hypothesis of neotropical anachronisms, this theory has not been confirmed for more than forty years.”
“Our study provides direct fossil evidence that confirms it.”
In the study, Dr. González-Guarda and the co-authors analyzed 96 fossil teeth of the South American Pleistocene Mastodon Notiomastodon plansis.
The fossils were collected over a period of more than 1,500 km, from Los Vilos to Chiloé Island in southern Chile.
Almost half of the specimens came from the emblematic site of Lake Tagua Tagua, an old lake basin rich in pleistocene fauna, located in the current O’Higgins region.
“To understand the lifestyle of Notiomastodon plansisWe used various techniques: isotopic analysis, microscopic studies on dental wear and fossil calculation analysis, ”said the authors.
“We have found starch residues and typical plant tissues of fleshy fruits, like those of the Chilean palm (Jubaea Chilensis), “Added Professor Florent Rivals, researcher at ICREA, IPHS-CARCA and the Rovira I Virgili University.
“This directly confirms that these animals frequently consume fruit and have played a role in the regeneration of forests.”
“Thanks to a stable analysis of the isotopes, we were able to rebuild the environment and the food of animals with great precision,” said Dr. Iván Ramírez-Pedreraza, researcher at Iphs-Cerca and Universitat Rovira I Virgili.
“The data indicates a wooded ecosystem rich in fruit resources, where mastodons have traveled long distances and dispersed the seeds along the way. This ecological function remains not placed. “
“Dental chemistry gives us a direct window on the past,” said Dr. Carlos Tornero, a researcher at Iphus-Cerca and the Autonomous University of Barcelona.
“By combining different lines of evidence, we were able to confirm their frugivory robustly and the key role they played in these ecosystems.”
The researchers also applied an automatic learning model to compare the current conservation status of factories depending on the megafauna in different South American regions.
Their results are alarming: in the center of Chile, 40% of these species are now threatened – a rate four times higher than in tropical regions where animals such as taps or monkeys always act as alternative seeds.
“When this ecological relationship between plants and animals has been fully broken, the consequences remain visible, even thousands of years later,” said Dr. Andrea Loayza, researcher at the Ecología Y Bidiversidad Instituto.
“Species like Gomorta (Gomous), the Chilean palm and the monkey puzzle tree (Araucaria Araucana) now survive in small fragmented populations with low genetic diversity. »»
“These are living remains of an extinct interaction.”
The results were published today in the journal Ecology and evolution of nature.
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E. González-Guard and al. Fossil proof of the ProBoscidian frugivoire and its lasting impact on South American ecosystems. Nat Ecol Evolutionpublished online on June 13, 2025; DOI: 10.1038 / S41559-025-02713-8
