The genus is named after Georges Muller, a French explorer, who was killed in 1892 by hostile members of the Sakalava people.

Mullerornis is smaller than the more well-known Aepyornis,[3][4] with a still substantial body mass of approximately 80 kilograms (180 lb).

[5] A bone possibly belonging to Mullerornis has been radiocarbon dated to about 1260 BP,[6] suggesting that the animal was still extant at the end of the first millennium.

[8] Like other elephant birds and its kiwi relatives, Mullerornis probably was nocturnal based on the small size of its optic lobes, though it shows less optical lobe reduction than these other taxa, implying slightly more crepuscular habits.

[10] The eggs of Mullerornis are substantially smaller than those of Aepyornis, weighting approximately 0.86 kilograms (1.9 lb), with a shell thickness of about 1.1 mm (3⁄64 in).