The Earliest-Known Stem  Mammals

DESCRIBER    Hahn et al., 1991
TIME    Triassic Late
Rhaetian
CLASS    Mammalia
SUBCLASS    Incertae Sedis
ORDER    Morganucodonta (Kermack, et al., 1973)
FAMILY    Megazostrodontidae (Gow, 1986)
FOSSILSITE    Keuper Formation, Saint-Nicolas-de-Port, Lorraine, France
INFO    
Brachyzostrodon coupatezi (Sigogneau-Russell, 1983 ) > Brachyzostrodon major (Hahn et al., 1991)  > Brachyzostrodon sp. (Hahn et al., 1991) > Brachyzostrodon sp. (Jenkins et al., 1994 )

DESCRIBER    Jenkins et al., 1994
TIME    Triassic Late
Norian
CLASS    Mammalia
SUBCLASS    Incertae Sedis
ORDER    Morganucodonta (Kermack, et al., 1973)
FAMILY    Megazostrodontidae (Gow, 1986)
FOSSILSITE    Flemming Fjord Formation, Jameson Island, Greenland
INFO

Brachyzostrodon coupatezi (Sigogneau-Russell, 1983 ) > Brachyzostrodon major (Hahn et al., 1991)  > Brachyzostrodon sp. (Hahn et al., 1991) > Brachyzostrodon sp. (Jenkins et al., 1994 )

Incomplete morganucodontan material. The framentary nature of the specimen (half of a molar) leaves positive identification in question.