In 1970, a paleontological Polish-Mongolian expedition discovered two fragmentary specimens of a small theropod in the
Ömnögovĭ province of
Mongolia. The
type species,
Elmisaurus rarus, was named and described by
Halszka Osmólska in 1981. The generic name is derived from
Mongol '
or ', "foot sole", as the
type specimen consisted of a
metatarsus. The
specific name means "rare" in
Latin. The
holotype,
ZPAL MgD-I/172, consists of a left metatarsus fused with the
tarsalia. There are two
paratypes: ZPAL MgD-I/98, consisting of a right hand and foot, and ZPAL MgD-I/20, the upper part of the left metatarsus of a larger individual. In a 2001 study conducted by Bruce Rothschild and other paleontologists, 23 foot bones referred to
Elmisaurus were examined for signs of
stress fracture, but none were found. A second species,
E. elegans, was named in 1989 by
Philip J. Currie. This represented a North American form originally described as a species of
Ornithomimus by
William Arthur Parks in 1933, based on specimen ROM 781, a foot. Currie also referred the material of the American form
Caenagnathus sternbergi, based on a jaw fragment, to
Elmisaurus elegans. Due to their poor preservation and geographical distance from the type species, the classification of the American forms has been contentious. In 1997,
Hans-Dieter Sues stated that this supposed second species of
Elmisaurus should be referred to
Chirostenotes, as
C. elegans, though this position was not accepted by Currie. Other researchers, including
Teresa Maryańska,
Halszka Osmólska, and their colleagues, followed Sues in reassigning
E. elegans to
Chirostenotes. In 2020, Gregory Funston assigned the material to the new genus and species
Citipes. A 2021 article by Funston and colleagues suggested
Nomingia is a synonym of
Elmisaurus. ==Classification==