History has not been kind to the elephant bird of Madagascar. Standing nearly 10 feet tall and weighing up to 1,000 pounds — or so researchers believed — this flightless cousin of the ostrich went extinct in the 17th century, thanks in part to humans stealing their massive eggs, either to feed their own families or to repurpose them as giant rum flasks. Or both.
More recently, the bird’s designation as the heaviest in history was challenged by the discovery of the slightly larger, unrelated Dromornis stirtoni, an Australian flightless giant that went extinct 20,000 years ago.
But a new study seeks to restore the elephant bird’s heavyweight title. After taxonomic reshuffling and examination of collected elephant bird remains, researchers say that a member of a previously unidentified genus of the birds could have weighed more than 1,700 pounds, making it by far the largest bird ever known.
Over the centuries, scientists have competed to collect and display the largest elephant bird bones. But, “nobody’s done any real cohesive research on these birds,” said James Hansford, a paleontologist at the Zoological Society of London and lead author of the study, resulting in a taxonomic muddle for the feathered giants. As a result, more than 15 elephant bird species had been identified across two genera (the plural of genus, the name for a group of closely related species).
To sort out the elephant bird family tree, Dr. Hansford hoped to determine where one species ended and the next began. He traveled the globe with a measuring tape examining thousands of elephant bird bones. He then used data on modern birds and algorithms to help determine how large the birds might have grown.
His conclusion, published Wednesday in the journal Royal Society Open Science, is that there were actually three genera of elephant bird rather than two, and four species rather than 15: Mulleornis modestus, Aepyornis hildebrandti, Aepyornis maximus and Vorombe titan.
One of those species, A. maximus, had long been considered the heaviest elephant bird, until a British scientist in 1894 claimed to have discovered an even larger species, Aepyornis titan. Other researchers dismissed the finding, saying A. titan was simply an unusually large member of the A. maximus clan.
But Dr. Hansford reports that A. titan is not only its own species but a separate genus of much larger elephant bird, as evidenced by the distinct size and shape of all three limb bones. He has named the species and genus Vorombe titan; vorombe is a Malagasy word meaning “big bird.”
“They thought the second biggest elephant bird, Aepyornis maximus, was the biggest, and they estimated them to be about 400 to 500 kilos, which is correct,” said Dr. Hansford. (One hundred kilograms equals 220 pounds, roughly the weight of a grand piano.) But the newly discovered species is “a lot bigger, up to 800 kilos, perhaps twice the body mass of A. maximus.”
Dr. Hansford believes his study is the most rigorous examination of elephant birds in nearly a century, and that he has grouped outdated names under more accurate headings.
“Over the 19th and early 20th centuries, a lot of scientists were trying to make their claims of a new species based on very little evidence, like the fact that a bone was just a few millimeters longer than another bone,” he said. “It’s not just about size but about what represents a different shape as well.”
Although the elephant birds’ fate was sealed long ago, Dr. Hansford believes his work can contribute to conservation efforts on Madagascar, where many unique species of plants and animals are threatened.
“These birds spent millions of year co-evolving with plants and animals in Madagascar,” he said. “To help conserve some of the more chronically endangered plants in Madagascar, we need to understand the ecological interactions that we’ve lost.”