Lessons from the past: Predators are doomed when their prey vanishes

Across Earth’s long timeline, extinction often seems like a silent erasure. Yet behind many disappearances lies a chain of ecological tension. Researchers at the State University of Campinas (UNICAMP) in Brazil explored predator-prey dynamics.

The results of two new studies suggest predator-prey relationships shaped extinction patterns in ancient species. Supported by FAPESP, the work focuses on predators like saber-toothed cats and their herbivore prey in North America.

The scientists used fossil records, body size data, and climate history from the last 20 million years.

Predators left without their prey

Saber-toothed tigers, known for long canines, likely hunted large animals. A popular theory links their extinction to the loss of megafauna during the late Pleistocene, caused by climate change and human actions.

“One of the hypotheses that’s received the most attention in the literature was that the end of saber-toothed tigers,” said study author and UNICAMP researcher João Nascimento.

“It could be linked to the extinction of megafauna at the end of the Pleistocene, which occurred between 50,000 and 11,000 years ago.”

“These large animals became extinct due to climate change and human actions, and as a result, the predators were left without their main prey.”

Extinction started before humans

Nascimento noted that the research offers a new timeline. “We found that the process began millions of years earlier,” he said.

Saber-toothed cats went through repeated extinctions over time, often during periods of reduced prey diversity. This long-term view changes how we understand their fate.

The second study, published in the journal Evolution, takes a reverse approach. It looks at how predator expansion drove herbivore decline. Antilocaprids, once a diverse group in North America, now have just one species left: the American antelope.

This group includes two extinct subfamilies. Merycodontinae vanished about six million years ago, likely outcompeted by proboscideans, ancestors of modern elephants. These massive animals dominated forest habitats, squeezing out smaller herbivores.

Predators vanished after prey

The Antilocaprinae subfamily started fading when felids grew more diverse. The American cheetah (Miracinonyx), built for speed, emerged during this time. It likely drove antelopes to become faster.

Predator-driven speed might be why the American antelope is so fast today. The study gives new weight to that idea. More predators meant more evolutionary pressure on prey species. Fewer herbivores meant fewer niches to support diverse predators.

In a previous study, the researchers had suggested that large herbivores in the Iberian Peninsula caused predator decline 15 million years ago. These new papers expand that perspective to much broader regions.

“The great contribution of this set of studies is precisely to present the idea that the interaction between predators and prey can have an effect on large evolutionary patterns,” said Professor Mathias Pires, who supervised the work.

“This had been debated for decades, but there was no really robust set of results to support this hypothesis.”

Fossils reveal extinction clues

These discoveries rest on detailed fossil records. The team analyzed size, diet, and coexistence patterns of animals across millions of years.

For example, saber-toothed cats appeared around 14 million years ago in Eurasia and 12 million years ago in North America. Eight species once coexisted, but numbers shrank over time.

Six million years ago, the saber-toothed cat population began a steady decline. This drop happened during a shift toward a more arid climate. Grasslands expanded while forests shrank, affecting food chains.

Leaf-eating prey lost their food sources, reducing available prey for predators.

“Our study did not find a direct relationship between this event and the reduction in saber-toothed cats, but these changes in the environment had an indirect impact on the extinctions of different saber-toothed species by reducing the availability of prey,” Pires said.

Predators and prey need balance

Forest-dependent Merycodontinae went extinct as their habitats disappeared. Grass-eating Antilocaprinae lasted longer but declined with increasing predator pressure. This chain reaction mirrors how nature balances itself.

“We’re showing how an increase in predators can reduce the availability of prey, which in turn reduces the abundance of predators, and how this can manifest on an evolutionary scale,” Pires said.

“It’s a warning about how we may be altering the future with the extinctions we’re causing now.”

The studies not only map the past but also warn how predator loss and extinction trends today may echo through millennia, reshaping life far beyond our own time.

The study is published in the Journal of Evolutionary Biology.

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