Ten thousand years after their extinction, mastodons still leave a mark on South America’s native forests. A new fossil-based study reveals how these ancient giants were once vital seed dispersers—and how their absence continues to threaten the ecosystems they once helped sustain.
Key Points at a Glance
- Fossil teeth show South American mastodons regularly ate fruit, supporting a long-held theory.
- Their extinction disrupted seed dispersal for many tree species, causing ecological imbalance.
- 40% of mastodon-dependent plants in parts of Chile are now threatened.
- New findings highlight the deep connection between extinct megafauna and forest health.
When the last mastodons vanished from South America some 10,000 years ago, it wasn’t just the end of a majestic species—it marked a turning point for entire ecosystems. A groundbreaking study, published in Nature Ecology & Evolution, has now delivered the first fossil evidence that these ancient relatives of elephants were frugivores—fruit eaters—and played a crucial role in dispersing seeds of large-fruited plants. Their loss echoes through forests even today.
Led by Erwin González-Guarda of the University of O’Higgins and IPHES-CERCA, with key contributions from universities including UAB and URV, the research analyzed 96 fossil teeth of Notiomastodon platensis, a Pleistocene mastodon. These remains, scattered along a 1,500-kilometer stretch from Los Vilos to Chiloé Island, told a consistent story: the mastodons’ diet included abundant fruit, such as the Chilean palm (Jubaea chilensis).
This discovery confirms a 40-year-old hypothesis proposed by ecologist Daniel Janzen and paleontologist Paul Martin, who suggested that many tropical plants evolved large, fleshy fruits to entice large herbivores that could spread their seeds. This co-evolutionary alliance was long suspected—but only now do we have the fossil data to back it up.
Using isotopic analysis, dental microwear studies, and even the detection of starch residues within fossilized calculus, the researchers reconstructed not just the mastodons’ diet, but the ecosystem they inhabited. The evidence painted a picture of mobile megaherbivores roaming dense forests, spreading seeds over long distances. When they disappeared, that crucial ecological service vanished too.
The repercussions are visible even now. Plants that once relied on these mastodons are today surviving in fragmented and genetically impoverished populations. The Chilean palm, the monkey puzzle tree (Araucaria araucana), and Gomortega keule are just a few examples of species struggling in the wake of this ancient extinction.
Using machine learning to analyze plant conservation status, the study found that regions where no other large frugivores remain—like parts of central Chile—have up to four times more endangered plant species than areas still visited by tapirs or monkeys. Where the seed dispersers are gone, the forest falters.
As Florent Rivals of IPHES-CERCA explains, “Paleontology isn’t just about the past. It’s a key to understanding what we’ve lost and what we might still save.” The study emphasizes the urgent need to consider ancient ecological roles when planning modern conservation strategies. Restoring or mimicking the function of lost megafauna could be crucial to preserving the genetic and ecological health of these forests.
By unveiling how ancient giants shaped modern ecosystems, this research invites us to reconsider extinction not just as a loss of species, but as the collapse of relationships—and offers a pathway for renewal rooted in the lessons of the deep past.
Source: Universitat Autònoma de Barcelona
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