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Ventura Pérez and the Case of the Elephant Bird

Scarred bones and a super-powered microscope suggest a new extinction theory. 


How did a respected bioarchaeologist and forensic anthropologist who usually investigates murders and gang violence become a key player in the story of an extinct giant bird?

Associate Professor of Anthropology Ventura Pérez ’00G, ’06PhD is a perimortem expert: he studies the circumstances of violent death, particularly how the death was done, and also if that death is displayed symbolically. Think of a gang leaving a body in the middle of a village to instill terror and send a message of threat. 

Elephant bird skeleton

Such violence leaves marks in bone. Pérez’s expertise is in sharp force trauma, such as chop marks and fractures. He made his name through pioneering the use of polysiloxane to make molds of the cut marks in bone. Polysiloxane is the same compound your dentist uses to create a mold of your teeth in order to construct a bridge. Pérez’s stroke of genius was to do what no one in his field had done before—to adopt this nondestructive technique for anthropologists to make impressions of bone.

Pérez’s studies necessarily take him into the past, whether recent past or long past. Those studies usually, however, concern human subjects—not animals that look like they stepped out of science fiction.



Elephant birds, of genus Aepyornis and genus Mullerornis, were huge flightless birds once widespread on the island of Madagascar. They weighed more than a thousand pounds and had an imposing height of over nine feet, much more massive than, and half again as tall as an ostrich. 

Some remarkable elephant bird bones were found in 2009 in Christmas River in south central Madagascar, remarkable because of the marks left in them and also for the particular moment at which those marks were laid. 

Christmas River is the site of a fossil bone bed containing an abundance of ancient animal remains—extinct megafauna including giant lemurs, Voay crocodiles, and Malagasy hippos. Miners excavating for gemstones found the layer of bones and contacted the local university, which brought the bones into its collection. 

James Hansford, a paleontologist for the Zoological Society of London who studies elephant birds, reviewed the bones from Christmas River. Hansford radiocarbon dates bones and takes isotopes from them to determine such things as what the birds ate. Looking at the bones from Christmas River, he became very excited, because during the narrow time horizon when the birds died and were buried, the bones also showed evidence of human butchery—marks that didn’t look as if they came from a natural cause, but rather from tools. 

At first Hansford didn’t believe what he was seeing. The bones came from a long time before humans were thought to have been on the island. Humans were supposed to have arrived on Madagascar between 2,500 and 4,000 years ago, yet these bones, and the marks upon them, were easily 10,000 years old. 

But how do you prove that the cuts were made by people? Hansford wanted verification, because he knew that if he was having trouble believing this, others weren’t going to believe it either. He had to show that the marks were in fact tool marks. And this is where Pérez got involved.

Doing research on ancient Madagascar wildlife is something of a side project for Pérez. It was his relationship with Laurie Godfrey, UMass Amherst emeritus professor of anthropology and one of Pérez’s mentors, that inadvertently made him known to paleontologists studying the island: Godfrey enlisted him to analyze butchery marks on the bones of giant lemurs, another extinct megafauna indigenous to Madagascar. Since then, through Godfrey and her colleagues, Pérez has developed a reputation as a go-to person for Malagasy subfossil bone analysis, a development Pérez regards with faint bemusement. In his office, a plush ring-tailed lemur that his wife gifted him in a spirit of fun peers from amid Pérez’s Southwestern and Mexican artifacts and decor, looking surprised to find itself there.

The Christmas River research team brought the bones—the tibiotarsus and tarsometatarsus, which fit together, and are unique to birds—to Pérez. The bones arrived at a fortuitous juncture.



Pérez’s polysiloxane technique is painstaking and methodical. It involves making negative and positive impressions of the mark left in a bone, and then “thin-sectioning” the positive impression, looking at those sections under a microscope to get a profile and then measuring to analyze for elements such as what soft tissue was present, and what type of tool was used. 

In 2017, however, Pérez became a beneficiary of a new, state-of-the-art instrument. The College of Social and Behavioral Sciences bought a $85,000 Keyence VHX5000 microscope with the help of the donor-supported Faculty Excellence Fund. 

The Keyence microscope has upped Pérez’s game. He is now able to apply the deep insight and knowledge he gained probing around fractures in three dimensions to a whole new medium.  “What used to take 72 hours per cut mark—to make the cast, make the mold, thin-section it, put it in an ultrasound water bath to get all the loose material out of the thin section, mount it to the slide, do the analysis—the microscope can do in four seconds without damaging the bone,” he explains. The Keyence takes a 3-D image from hundreds of focal points instantly, and built-in visualization software allows Pérez to “digitally dissect” that image, maneuvering his point of view 360 degrees within the cut mark of the bone. The microscope records the width, depth, and curvature of the bones.

So, when the elephant bird bones arrived in Pérez’s Violence and Conflict Lab in Machmer Hall, he had an even sharper view of them. “I had just gotten the microscope. I was amazed,” says Pérez. He told the researchers that what he was seeing looked like tool-induced dismembering marks. 



The discovery and dating of the bones, and the cut marks in them, have forced a revisitation of what was considered common knowledge, pushing back the human occupation of Madagascar to a much earlier time. The findings suggest that human presence on the island could go back as far as 10,000 years, or even farther.

Elephant bird bone

The Aepyornis maximus tibiotarsus bone from the Christmas River site.

This discovery has caused ripples in the academic community—many scholars have a lot professionally invested in the arrival of humans during a certain time range. But it disturbs the waters even deeper than that, because it also suggests a completely different extinction theory—that rather than pressuring the birds out of existence in a rather short span of time, humans could have lived alongside them for thousands of years. 

It has been understood that the arrival of humans on Madagascar drove megafauna like elephant birds, giant lemurs, and the Malagasy hippopotamus to extinction over a few centuries, both through hunting and also competition for habitat, as when humans started clearing forests to create agricultural fields. Yet if humans arrived much earlier to the island, that creates several potential whorls in the narrative: either there was more than one human migration to Madagascar and the earlier humans did not stick around, or, if humans were on the island continuously, perhaps their living system at some point changed to make coexistence with these large animals no longer sustainable.

“Something else happened around 1,000 years ago, and it was big,” says Laurie Godfrey—something caused the megafaunal populations to crash. She speculates that the expansion of the trade network that crisscrossed the Indian Ocean could have caused more people to settle on Madagascar: a greater human population would start relying more heavily on agropastoralism than on more sustainable hunting and foraging. Or there could have been multiple waves of occupation. 



Why is this insight so important? “We want to understand what happened in Madagascar because it’s a microcosm of things that are happening in other places,” explains Godfrey. The story has modern resonance. “We live in a world that is very changed by people. People had a big impact on this island.”

Madagascar offers a test case because it’s a biodiversity hot spot with high endemicity—its flora and fauna have evolved there and nowhere else. Rich with life and in its own fragile balance, the Texas-sized island illustrates in a contained way such ecological factors as what happens when invasive species are introduced, and what happens to native wildlife when humans burn habitat to clear fields for crops and grazing. 

It’s easy to trace causality because all of this has happened relatively recently. While we might picture elephant birds in our mind’s eye as being pursued by cavemen with spears, they actually existed on Madagascar until around 1,000 years ago, which in evolutionary terms is practically contemporary to life as we know it today. There have even been suggestions that the birds may have survived in the island’s interior, in pockets of population remote from humans, until much later than that. A European merchant in the 1600s describes surprising a similar animal on a foray into the brush and then killing it with his musket. On his return to Europe, he hoped to make a present of the animal’s skin, the “skin of a dragon,” to Louis XIV. 



What caused the extinction event on Madagascar? If we still accept that it was humans, what was the change in human activity that brought it about? Which humans, when, and why? “There is a difference in saying humans had a hand and then being able to say exactly what happened, so the argument is about sequence of events,” comments Godfrey. 

The biologists have much more excavation and study to do, such as determining if the Christmas River site is in fact a kill site, or whether the bones were washed up and deposited from somewhere else. Introducing a radically different extinction theory means opening up countless boxes full of new questions.

In the meantime, we can hold these takeaways: That when scholar-investigators of Pérez’s caliber have access to cutting-edge technology, the whole ground of investigation can shift. That understanding what happened in the past, the causal mechanisms behind ecological change, can help us create workable strategies for restoration. 

And, in case you were wondering: these famous avian foot bones are now in the Smithsonian.  


Photo of Ventura Pérez by John Solem