Researchers Find Large Animal
Extinction Evidence in Madagascar

After uncovering fossil evidence in Madagascar, Professor David Burney, Ph.D., and his Fordham research team have confirmed suspicions that the arrival of humans to the island some two millennia ago led to the extinction of flightless birds, giant lemurs and other large animals.

Burney, together with Guy Robinson, Ph.D., and Lida Pigott Burney, published their findings in an article titled “Sporormiella and the Late Holocene Extinctions in Madagascar,” which appeared in the Sept. 16 issue of the Proceedings of the National Academy of Sciences.

The team’s discovery came after analyzing island sediment samples for fossil spores of a fungus called Sporormiella, which is found primarily on the dung of large mammals. The fossil evidence suggests that there was an abundance of megafunga (animals weighing more than about 100 pounds) on the island until around 200 AD. After that, for the next 200 years or so, the fungus essentially disappeared, which the researchers attribute to humans hunting the beasts.

The absence of animals such as giant lemurs, flightless elephant birds, giant tortoises and pygmy hippopotami, who were no longer grazing and browsing the terrain, created an overabundance of brush that fueled devastating fires in the area. The researchers confirmed this through studying charcoal evidence also in the sediment.

However, according to the researchers, extinction did not occur right away. High-precision radiocarbon dating evidence presented in the article shows that after humans arrived and the system collapsed, small populations of these species survived for 1,000 years or more. The eventual introduction of livestock and other invasive species to the ecosystem by humans (indicated by a return of the spores to the sediments about a millennium ago) probably increased competition for food and brought diseases and other biological disruptions to the system.

“What you have here is a domino effect, an interaction of multiple causes culminating in the extinction of these animals,” said Burney, an associate professor of biology who is currently conducting field research in Hawaii. “A problem that scientists have always had with the evidence was explaining how a small number of people with primitive hunting weapons could disrupt an ecosystem system so quickly. We found that it was most likely the interactive effects of human activities that account for the depth of these extinctions, which eventually eliminated the entire mega fauna on Madagascar.”

This is not the team’s first discovery related to large mammal extinction. Using similar research methods at four sites in southeastern New York, the team determined that humans, not dramatic climate changes, led to the extinction mammoths, mastodons, and other large beasts in North America some 10,000 years ago. This undertaking was the basis of Guy Robinson’s doctoral research project in Professor David Burney’s lab.

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