Oct. 31 (UPI) -- Elephant birds -- flightless birds that measured more than 10 feet tall -- lived alongside humans before they went extinct from 500 to 1,000 years ago, according to research from the University of Texas.
Researchers at the university said the birds, which lived in Madagascar, were nocturnal and possibly blind, based on the examination of their brain shape. The findings were released Wednesday in the journal Proceedings of the Royal Society B.
Scientists had digitally reconstructed the brain of the extinct bird in their research, learning that its optic lobe was virtually absent, a trait that indicates it was nocturnal and possibly could not see.
Researchers had previously believed that the elephant birds were much like other large flightless birds, such as the emus and ostriches. Those birds are both active in the daylight and have good eyesight.
The BBC News wrote that the birds weight a half-ton and laid eggs that were bigger than most dinosaur eggs.
Christopher Torres, a Ph.D. candidate who led the research, and Julia Clarke, a professor at the University of Texas's Jackson School of Geoscience said the brain examination led them to completely different conclusions.
"No one has ever suspected that elephant birds were nocturnal," Torres said in a university statement. "The few studies that speculated on what their behavior was like explicitly assumed they were active during the day."
Torres said he speculates that humans may have had something to do with the birds' ultimate demise.
"Humans lived alongside, and even hunted, elephant birds for thousands of years," Torres said. "But we still know practically nothing about their lives. We don't even really know exactly when or why they went extinct."
Researchers also found that the part of the brain that processes smell helped explain the habitats where elephant birds lived. The larger of the two species of elephant bird had a large olfactory bulb, a trait associated with forest dwelling.
The smaller species also appears to have better vision, which means it may have been more active at dusk than in the dark.
"Details like these not only tell us about what the lives of elephant birds were like, but also what life, in general, was like on Madagascar in the distant past," Clarke said. "As recently as 500 years ago, very nearly blind, giant flightless birds were crashing around the forests of Madagascar in the dark. No one ever expected that."
Popular Science wrote that the discovery could help researchers learn more about the evolutionary tree that sprouted the kiwis -- the elephant birds' closest living relative -- along with the emus, cassowaries, moas, rheas and tinamous.