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https://www.nature.com/articles/s41467-026-76105-2 : Lower speciation, not higher extinction, drove African megaherbivore diversity collapse

A study by the National Museum of Natural Sciences (MNCN-CSIC), the National Research Center on Human Evolution (CENIEH) and the University of Alcalá offers a new explanation for the decline of African megaherbivores.

These animals, weighing more than a tonne (2,200 pounds) and today including elephants and hippopotamuses, are known for acting as ecosystem engineers.

The results, published in Nature Communications, reveal that their loss of diversity throughout history was not due to their being more vulnerable to extinction, as had previously been proposed, but rather that their decline was driven by particularly low rates of speciation : the emergence of new species.

Summary: Around 7.2 million years ago, Africa's climate began to grow drier, driving changes in landscapes and vegetation types that led to a reconfiguration of ungulate communities (hoofed mammals). At the start of this phase, both the emergence of new species and the disappearance of others increased.

However, 3.6 million years ago, new species stopped emerging at the same pace, while extinctions kept rising and accelerated at the onset of the Pleistocene, 2.58 million years ago.

These data show that the loss of diversity among large-bodied animals was already noticeable long before humans had the technological capacity to hunt animals of that size.

Species affected by this decline include Deinotherium, an extinct relative of elephants distinguished by its downward-curving tusks, and the Anthracotheriidae, animals related to hippopotamuses that resembled a large pig.

"We found that, contrary to what was previously thought, larger species did not go extinct faster than smaller ones. In fact, their extinction rates were somewhat lower. The key is that megaherbivore species gave rise to new species much more slowly," explains MNCN researcher Juan López Cantalapiedra.