Fossil Evidence Reveals South American Mastodons Consumed Fruits

Recent research has confirmed that South American mastodons, specifically the extinct species Notiomastodon platensis, were regular consumers of fruits, thereby playing a significant role in their ecosystem. This study, published on June 13, 2025, in the journal Nature Ecology & Evolution, presents fossil evidence suggesting that these large herbivores were crucial for seed dispersal in their habitat, which has implications for understanding the evolution of certain plant species in South America.

The phenomenon known as the neotropical anachronism hypothesis, initially proposed in 1982 by biologist Daniel Janzen and paleontologist Paul Martin, posited that many tropical plants evolved large, fleshy fruits to attract now-extinct megafauna, including mastodons. Despite its theoretical significance, robust empirical evidence supporting this hypothesis had been lacking until now. Dr. Erwin González-Guarda, a paleontologist at the University of O’Higgins and IPHES-CERCA, and his research team have provided direct fossil evidence confirming that Notiomastodon platensis actively consumed fruits, offering new insights into the ecological roles of extinct megafauna.

The research team analyzed 96 fossilized teeth collected over a distance of more than 1,500 kilometers from locations in Los Vilos to Chiloé Island. Dr. González-Guarda stated, “Our study provides direct fossil evidence that confirms the theory we have proposed for decades.” The analysis involved various techniques, including isotopic analysis and microscopic dental wear studies, which revealed starch residues and plant tissues characteristic of fleshy fruits, notably from the Chilean palm (Jubaea chilensis).

Dr. Florent Rivals, a researcher at ICREA, IPHES-CERCA, and the Universitat Rovira i Virgili, commented, “This directly confirms that these animals frequently consumed fruit and played a role in forest regeneration.” The isotopic analysis indicated that mastodons inhabited a forested ecosystem rich in fruiting plants and traveled considerable distances, thus facilitating the dispersal of seeds.

Moreover, the study analyzed the current conservation status of plants dependent on megafauna for seed dispersal across South America. The results were alarming: in central Chile, 40% of these species are now threatened, a rate four times higher than in tropical regions where alternative seed dispersers, such as tapirs and monkeys, still exist. Dr. Andrea Loayza of the Instituto de Ecología y Biodiversidad emphasized, “Where that ecological relationship between plants and animals has been entirely severed, the consequences remain visible even thousands of years later.”

The findings not only shed light on the dietary habits of mastodons but also reflect on the long-term impacts of their extinction on South American ecosystems. Species such as Gomortega keule, the Chilean palm, and Araucaria araucana now exist in fragmented populations, with low genetic diversity, as remnants of an ecological interaction that has been lost. The research underscores the importance of understanding historical ecological relationships to inform current conservation efforts.

As ecosystems face increasing threats from human activity and climate change, this study highlights the need for a comprehensive approach to conservation that considers the benefits of megafauna in ecosystem health. The ongoing loss of biodiversity calls for urgent action to protect the remaining species and restore ecological balance in regions where the legacy of extinct megafauna continues to resonate.