Extinct megafauna were “engineers” who shaped the ecosystems of Central and South America

The megafauna includes large animals that are often charismatic. It’s usually the first thing that comes to mind when we think of wildlife conservation. Think elephants, rhinos, giant pandas and tigers.

There is also an abundance of extinct megafauna in the fossil record, such as mammoths, saber-toothed cats and giant wolves. Extinct megafauna aren’t just a fascinating glimpse into the past – their existence shapes aspects of current ecosystems in interesting ways. For example, a new study has found evidence that extinct megafauna are important drivers of ecosystem geography in Central and South America.

Glyptodon is an example of extinct South American fauna – a relative of armadillos. Credits: Pavel Riha / The Conversation.

Modern megafauna animals are often described as ecosystem engineers and keystone species for the important role they play in shaping their environment. Elephants, for example, are the largest land animals in the world, with males weighing up to 7 tons. They shape their environment in several important ways, including tending grasslands and spreading plant seeds. Although different megafauna animals have different impacts on the environment, they all play an important role. So how did animals that lived in the past affect their environment?

This new study sheds some light on this question.

What the new research found

The article focuses on the Neotropical realm – consisting of tropical Central America and all of South America. The researchers wanted to know to what extent variability in plant traits and ecosystem geography could be explained by extinct megafauna – defined by the authors as extinct herbivorous mammals weighing more than 50 kg. What they found was that “the extinct megafauna left a significant imprint on the current biogeography of the ecosystem.”

The authors found that many of the plant traits they studied were significantly influenced by the presence of megafauna. These plant characteristics included wood density, thorns on leaves for defense, leaf size, etc. These findings mean that the ecology of extinct megafauna is a hugely important part of understanding plant evolution – one that has been “largely overlooked in the ecological literature” according to the authors.

They also found that, like modern elephants, extinct megafauna probably also had a role in maintaining grasslands. They discuss how megafauna extinction events may have played an important role in the shift from grassland ecosystem to forest ecosystem that occurred in South America, and state that “extinctions of megafauna could largely explain the current prevalence of forests on the continent”.

The article was published in Nature Communications on January 10, 2022.