The jaws were found in 1917 by
Charles Hazelius Sternberg and sons in the
Dinosaur Provincial Park in
Alberta at the
Little Sandhill Creek site. In 1924
Charles Whitney Gilmore named
Chirostenotes pergracilis and referred the jaws to this species. In the 1980s it became clear that
Chirostenotes was an
oviraptorosaur to which the long jaws could not have belonged. Therefore, in 1990
Phillip Currie,
John Keith Rigby and
Robert Evan Sloan named a separate species:
Richardoestesia gilmorei. The genus is named for
Richard Estes, to honor his important work on small vertebrates and especially theropod teeth of the Late Cretaceous. The naming authors actually intended to use the spelling
Ricardoestesia,
Ricardus being the normal latinisation of "Richard". However, except in one overlooked figure caption, the editors of the paper altered the spelling to include the 'h'. Ironically, in 1991 George Olshevsky in a species list also used the spelling
Richardoestesia, and indicated
Ricardoestesia to be the misspelling, unaware that the original authors actually intended the name to be spelled this way. As a result, under
ICZN rules, he acted as "first revisor" choosing between the two spelling variants of the original publication and inadvertently made the misspelt name official. Subsequently, the original authors have adopted the spelling
Richardoestesia. The
specific name honors Gilmore.
Species The
holotype specimen of
Richardoestesia gilmorei (NMC 343) consists of a pair of lower jaws found in the upper
Judith River Group, dating from the
Campanian age, about 75 million years ago. The jaws are slender and rather long, 193 millimeters, but the teeth are small and very finely serrated with five to six denticles per millimeter. The serration density is a distinctive trait of the species. In 2001,
Julia Sankey named a second species:
Richardoestesia isosceles, based on a tooth, LSUMGS 489:6238, from the Texan
Aguja Formation, which is of a longer and less recurved type. The teeth of
R. isosceles have also been identified as
crocodyliform in shape, possibly belonging to a
sebecosuchian. In 2013 a study assumed that the teeth of the
coelurosaur Asiamericana asiatica, from the CBI-14 site of the
Bissekty Formation in
Uzbekistan, were identical to those of
Richardoestesia isosceles, and renamed the species into
Richardoestesia asiatica. A subsequent study confirmed this in 2019. The holotype of
R. asiatica is CCMGE 460/12457, and two other teeth (ZIN PH 1110/ 16 and ZIN PH 1129/16) are also known. == Classification ==