When the first
specimens were originally
described by
Richard Owen in 1846, they were placed within the
genus Dinornis as three different species. These remains would later be split off into their own genus,
Emeus. The other two species,
E. casuarinus and
E. huttonii are currently regarded as junior synonyms of
E. crassus, and the genus currently contains this single species. It has been long suspected that the "species" described as
Emeus huttonii and
E. crassus were
males and
females, respectively, of a single species. This has been confirmed by analysis for sex-specific genetic markers of
DNA extracted from bone material; the females of
E. crassus were 15-25% larger than males. This phenomenon —
sexual dimorphism — is not uncommon amongst ratites, being also very pronounced in
kiwi and the related moa genus
Dinornis. ==Description==