The term Hystricomorpha has had many definitions throughout its
history. In the broadest sense it refers to any rodent (except
dipodoids) with a hystricomorphous zygomasseteric system. This
includes the Hystricognathi, Ctenodactylidae, Anomaluridae, and
Pedetidae. Molecular and morphological results suggest that the
inclusion of the Anomaluridae and Pedetidae in Hystricomorpha
may be suspect. Based on Carleton and Musser (2005), these two
families are treated here as representing a distinct suborder
Anomaluromorpha. The modern definition of Hystricomorpha also
known as Entodacrya or Ctenohystrica is a taxonomic hypothesis
uniting the gundis with the hystricognath rodents (Carleton and
Musser, 2005). There is considerable morphological support for
this relationship and strong molecular support. If true, this
hypothesis renders the traditional view of Sciurognathi invalid
as it becomes a paraphyletic group. The hystricomorph rodents,
or at least members of Caviomorpha, are sometimes regarded as
non-rodents (Gra