An artist's illustration of the giant elephant bird.
An artist's illustration of the giant elephant bird. c Jaime Chirinos

A new study report published in the journal Proceedings of the Royal Society B suggested that elephant birds that went extinct from the earth between 500 and 1000 years ago were nocturnal and blind.

Researchers who took part in the study also revealed that elephant birds which stood 10 feet tall in Madagascar in the ancient times were the largest bird species ever to roam on earth, much larger than the Sesame Street's Big Birds.

Previously, it was believed that elephant birds shared similar characteristics to emus and ostriches which are the largest birds in the modern world. Experts believed that elephant birds were usually active on the day and had an impeccable eyesight. However, after analyzing two elephant bird skulls from two species, researchers have now found that these birds were actually blind and nocturnal just like the tiny Kiwis living in New Zealand.

"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" said Julia Clarke, a professor at the University of Texas Jackson School of Geosciences and the co-author of the study.

During the study, researchers found that the skulls of elephant birds were fit tightly around their brains. Brain reconstruction research conducted on elephant birds' skulls revealed that optical lobes that control the eyesight were almost absent.

Researchers believe that the nocturnality among elephant birds might be due to an inherited trait from their ancestors. But, the real reason which played a crucial role behind the extinction of elephant birds from the planet. Experts speculate that several factors including hunting, habitat destruction and climate change might have contributed to the extinction of these creatures from the earth.

"A nocturnal lifestyle is often an evolutionary response either when it's too dangerous to come out during the day or when what you eat comes out at night. Species in this group that live in forests seem to rely on a well-developed sense of smell to help them forage in conditions where visual cues might be obstructed," said Christopher Torres, a Ph.D. student at the University of Texas and the study's co-author.