The holotype of
Agorophius pygmaeus,
MCZ 8761, was first mentioned in an 1848 report on the geology of South Carolina by Michael Tuomey. It was eventually described as
Zeuglodon pygmaeus by
Johannes Peter Müller in 1849. Louis Agassiz coined the name
Phocodon holmesii for the same specimen, classifying it as an odontocete. Later authors considered
Zeuglodon pygmaeus a species of either
Dorudon or
Squalodon, and in 1895
Edward Drinker Cope eventually recognized it as being a distinct genus, which he named
Agorophius. Although the skull is lost and the tooth is the only extant part of MCZ 8761, Fordyce (1981) was able to diagnose
Agorophius based on existing descriptions of the skull by Muller, Cope, and Agassiz. New specimens from the
Ashley Formation and
Chandler Bridge Formation have provided new data on
Agorophius, distinguishing it from other Oligocene odontocetes from the US Eastern Seaboard by the condition of its intertemporal condition. ==Classification==