It looks like we can add the gomphothere, an ancestor to the elephant, to the list of animals humans have driven extinct. It was once thought that gomphotheres had died out before the first humans reached North America, but new evidence suggest it lived long after humans arrived.

Not only have University of Arizona paleontologists found gomphothere bones recent enough to coincide with human settlement, they found them mixed in with weapons, indicating the prehistoric elephants were probably dinner for the hunters.

Gomphotheres were as large as modern elephants and dominated North America from 12 million years ago until going into decline around around 2 million years ago. They also flourished in Asia and South America. The cause of their demise has been much debated. Competition from more specialized feeders appears to have played a part, along with climate change, but the main topic of debate was whether humans contributed.

This feeds a wider issue. All over the world, aside from Africa, the latter part of the Quaternary Period saw most of the largest land animals become extinct. In some cases it is clear that humans, either as hunters or rivals, were responsible. In others, the issue is not settled. The debate is considered to have important implications for the current mass extinction. 

Until relatively recently it was thought that gomphotheres went extinct from North America and the northern part of South America long before humans arrived. Consequently, debate about our role in their demise centered on areas that are now Argentina and Chile. However, in 2011 human weapons were found in association with gomphothere bones in Columbia. Now a similar find has been made in Mexico.

In 2007 rangers in northwestern Sonora informed Professor Vance Holliday of some very large fossils. “At first, just based on the size of the bone, we thought maybe it was a bison, because the extinct bison were a little bigger than our modern bison," says Holliday. However, the discovery of a jawbone made clear that they were dealing with gomphothere remains. In the Proceedings of the National Academy of Sciences the bones are revealed as 13,400 years old. 

^{Joaquin Arroyo-Cabrales/Instituto Nacional de Antropología e Historia. The Jawbone that revealed the bones to be relatives of elephants.}

Any question of human involvement disappeared when Holliday found spear tips and cutting tools among the bones, including one with bone fragments both above and below. The tools bear the distinctive style of the Clovis culture.

^{Vance Holliday/University of Arizona. Archeologists extracting the crucial jaw.}

Since more northerly Clovis populations are known to have hunted mammoths, which were even larger than gomphotheres, it is no surprise surviving gomphotheres would have been targeted.

"This is the first Clovis gomphothere. It's the first evidence that people were hunting gomphotheres in North America, and it adds another item to the Clovis menu," says Holliday.