During the 19th century, European explorers enthusiastically combed Madagascar in search of the remains of the extinct elephant bird—one of the island’s now-vanished megafauna, which left behind huge skeletons and the largest eggs of any known vertebrate. Naturalists subsequently attempted to categorize different elephant bird species, but their approach doesn’t hold up to modern scientific rigors; the classification of at least one species, for instance, was based solely on eggshell fragments.
A new study, published in Royal Society Open Science, attempts to bring some order to the elephant bird’s family tree. And as Douglas Quenqua reports for the New York Times, researchers have identified a new species of elephant bird that can claim the distinction of being the heftiest bird to ever walk the Earth—quite literally, since elephant birds could not fly.
The hulking creatures were last seen in the 17th century, likely driven to extinction by a combination of climate change, shifts in vegetation patterns and humans’ pillaging of elephant bird eggs, which were roughly equal to 150 chicken eggs in volume and could easily feed several families. Scientists who studied these birds in the past organized them into 15 species divided between two genera.
Unfortunately, naturalists’ attempts to describe the birds were not particularly accurate. Few complete skeletons were found, so, according to Gemma Tarlach of Discover, collectors often pieced together skeletons out of unrelated bones. And as zoologists James P. Hansford and Samuel T. Turvey of the Zoological Society of London write in the new study, historic efforts at classification bore “no realistic consideration of natural variation within taxa, and often interpreted marginally observable differences as being taxonomically important.”
The authors also note that elephant birds have been subjected to “remarkably little study” in recent years. So Hansford, equipped with a tape measure and a caliper, set out to study hundreds of elephant bird bones held in museum collections around the globe.
In total, Hansford analyzed at 346 specimens, only 82 of which were intact. The researchers then used advanced statistical analysis to cluster the specimens into different groups. Their results indicated the elephant birds fall into just four species—not 15—across three genera. The species identified by the study authors are Aepyornis hildebrandti, Aepyornis maximus, Mulleornis modestus and Vorombe titan.
V. titan is a new addition to the elephant bird family tree, but one that has its roots in the work of 19th century British scientist C.W. Andrews. The first elephant bird to ever be described, Aepyornis maximus, was also believed to be the largest, measuring nearly 10 feet high and weighing up to 1,000 pounds. In 1894, Andrews identified an even bigger species, Aepyornis titan, but other researchers tended to believe that the bird was just an unusually large A. maximus, according to a Zoological Society of London press release.
The new study, however, shows that Andrews’ “titan” elephant bird was in fact a distinct species. The researchers named it Vorombe, from the Malagasy term for “big bird,” and titan in a nod to Andrews.
The team’s algorithms helped them determine how big different elephant bird species may have grown; V. Titan, Hansford tells Quenqua of The New York Times, had “twice the body mass of A. maximus,” meaning that it could have weighed around 1760 pounds. That is also heavier than the Dromornis stirtoni, an extinct, giant bird from Australia that could weigh around 1100 pounds and is sometimes described as the world’s largest known bird.
Having detailed information about elephant birds is important because, like other megafauna, they played an important role in Madagascar’s ecosystem: they controlled vegetation by eating plants, for instance, and spread seeds through defecation. The birds’ extinction is still having an impact on the island.
“Without an accurate understanding of past species diversity, we can’t properly understand evolution or ecology in unique island systems such as Madagascar or reconstruct exactly what’s been lost since human arrival on these islands,” Turvey says in the Zoological Society of London statement. “Knowing the history of biodiversity loss is essential to determine how to conserve today’s threatened species.”