It has been confirmed that the extinction of large herbivorous animals, resembling elephants, significantly impacted tropical plants at the time. With the disappearance of these large animals, even the plants coexisting in the ecosystem were unable to spread their seeds, leading them down the path of extinction.
An international collaborative research team led by O'Higgins University in Chile published on the 13th (local time) their findings from the analysis of 96 mastodon fossil teeth using multiple analytical methods in the international journal "Nature Ecology & Evolution."
The mastodon, a distant relative of elephants, is believed to have gone extinct about 10,000 years ago. It had long tusks like elephants and its fossils have only been excavated from North and Central America.
The research team secured 96 mastodon fossil teeth collected over approximately 1,500 km from Los Villos in southern Chile to Chiloé Island. More than half of these were excavated from the site "Lake Taguatagua," where a large number of Pleistocene animal fossils have been found.
The research team focused on one hypothesis. Biologist Daniel Janzen and paleontologist Paul Martin proposed in 1982 that the large fruits of tropical plants evolved to attract giant animals like mastodons for seed dispersal.
However, there has been no direct evidence to substantiate this hypothesis for over 40 years. The research team utilized the fossil teeth of mastodons to verify this hypothesis. Through isotopic analysis, micro-wear analysis of teeth, and analysis of residual dental calculus, they reconstructed the diet of mastodons from 10,000 years ago. The result confirmed the existence of tropical plants that bore large fruits.
Dr. Florent Rival, a participating biogeochemist, said, "Starch and tissue remnants of fruits like Chilean palm were found in the fossil teeth of mastodons, which directly demonstrates that they frequently consumed such fruits and contributed to forest ecosystem regeneration."
The research team reports that mastodons played a role in dispersing the seeds of tropical plants over long distances. The problem is that after the extinction of large animals like mastodons, no species have emerged to take over this role.
The research team believes that the extinction of mastodons severed the co-evolutionary relationship between tropical plants and large animals that had persisted for thousands of years. After analyzing the conservation status of plants that were dependent on giant animals like mastodons across various regions of South America using artificial intelligence (AI), they found that 40% of such plants in central Chile are in a state of extinction crisis. This is more than four times the level compared to other plants that do not rely on giant animals.
Among the tropical plants that depended on giant animals, only a few species, like Gomortega keule, Chilean palm, and Araucaria araucana, have survived. Dr. Andrea Loaiza, a participant in the study, noted, "In regions where the ecological relationship between animals and plants has been completely severed, the consequences are clearly evident even after thousands of years."
References
Nature Ecology & Evolution (2025), DOI : https://doi.org/10.1038/s41559-025-02713-8