Introducing large herbivores in Panama’s forests could fill the gap left by extinct species, new research suggests .
University of Exeter scientists studied lake sediments that contain traces of animals and plants dating back 17,000 years.
Many large herbivores that once roamed modern-day Panama have declined or died out – including the six-metre-long giant ground sloth and elephant-related creatures called Cuvieronius.
The new study reveals three major declines of plant-eating “megafauna” (animals over 45kg): 13,600, 10,000 and 8,400 years ago.
Large herbivores have major impacts on ecosystems, and the study found forests and grasslands changed markedly when megafauna declined.
The team say their findings can provide a “baseline” for future rewilding to restore the ecological functions lost with the extinction of prehistoric megafauna.
“Just like elephants today, we found that large herbivores had a significant impact on ecosystems during the period we studied,” said lead author Felix Pym, from the University of Exeter.
“For example, there were fewer wildfires when large herbivores thrived – possibly because they ate and trampled on understorey vegetation that can fuel fires.
“Also, when megafauna declined, so did plants with large fleshy fruits and seeds that are typically spread by large animals.
“It’s visible from our record that the loss of megafauna had cascading impacts on ecosystem processes.”
The findings suggest that future declines of today’s large herbivores could have profound consequences for biodiversity.
Conversely, “rewilding” by introducing new species or increasing populations of existing ones could restore nature – and its benefits to humans.
“As a large proportion of megafauna species that lived during the study period are now globally extinct or have undergone severe declines, some rewilding efforts in Europe and North America have used the nearest equivalents and/or moved species from elsewhere in the world,” Pym said.
“Our study tells us something about what has been lost, and highlights a possible solution, but the selection of species for rewilding would require careful research and planning.”
Prehistoric poo
Explaining how the study worked, Pym said: “Large herbivores consume fungal spores from their environment, which are then excreted and grow into fungi in their dung.
“New fungal spores are dispersed, travel into lakes, and are then preserved in layers of sediment.
“The sediment also contains fossilised pollen, which allows us to identify plant species, and charcoal, which tells us when fires occurred.
“We took samples from sediments recovered from Lake La Yeguada and analysed them for fungal spores, pollen and charcoal – revealing lots of information about past animals, plants and wider ecosystems.”
Fungal spores only reveal that large herbivores were present – not yet specific species – but existing bone evidence shows species that lived in the region during the period.
The causes of megafauna decline are also debated, but the arrival and disturbance of humans in Central America are likely factors.
After the periods of megafauna decline discovered by the study, recoveries took place at 11,200, 9,000 and 7,600 years ago – probably due to changes in the communities of large herbivores in the region.
Professor Stephen Sitch, from Exeter’s Global Systems Institute , said: “This study uses a novel approach to give us a holistic understanding of the tropical environment through time, including interactions between animals, fire, vegetation and climate.
“Exploring the past can help us understand today’s tropical ecosystems, aid their conservation and together with rewilding approaches, help to restore lost ecosystem functions that we all benefit from.”
The study, carried out with partners in Colombia and the UK, was funded by the Natural Environment Research Council’s GW4+ Doctoral Training Partnership.
Pym’s PhD is primarily supervised by Dr Dunia H. Urrego, who also recovered the sediment core.
The paper, published in the journal Quaternary Science Reviews , is entitled: “ The timing and ecological consequences of the Late Pleistocene megafaunal declines on the Isthmus of Panama: Implications for trophic rewilding .”
Quaternary Science Reviews
10.1016/j.quascirev.2026.109887
Observational study
Animals
The timing and ecological consequences of the late Pleistocene megafaunal declines on the Isthmus of Panama: Implications for trophic rewilding
23-Feb-2026