Paramys delicatissimus was named by Leidy (1871). Its type locality is
Grizzly Buttes, which is in a Bridgerian terrestrial horizon in the Bridger Formation of Wyoming.
It was recombined as
Plesiarctomys delicatissimus by Cope (1877); it was recombined as
Reithroparamys delicatissimus by
Matthew (1920),
Wilson (1940),
Wood (1962),
Gazin (1976),
Korth (1984),
Emry and Korth (1989) and
Ivy (1990).