The Earliest-Known Stem  Mammals

DESCRIBER    Jenkins et al., 1983
TIME    Jurassic Early
’Liassic’ ?Sinemurian
CLASS    Mammalia
SUBCLASS    Incertae Sedis
ORDER    Morganucodonta (Kermack, et al., 1973)
FAMILY    Morganucodontidae (Kühne, 1958)
FOSSILSITE    Kayenta Formation, Gold Springs, Arizona, United States
FALL UNDER    Morganucodon watsoni