title: Mesozoic mammals from Arizona: new evidence on Mammalian evolution.
abstract: Knowledge of early mammalian evolution has been based on Old World Late Triassic-Early Jurassic faunas. The discovery of mammalian fossils of approximately equivalent age in the Kayenta Formation of northeastern Arizona gives evidence of greater diversity than known previously. A new taxon documents the development of an angular region of the jaw as a neomorphic process, and represents an intermediate stage in the origin of mammalian jaw musculature.
authors.forename: F A
authors.initials: FA
authors.lastname: Jenkins
authors.forename: A W
authors.initials: AW
authors.lastname: Crompton
authors.forename: W R
authors.initials: WR
authors.lastname: Downs