’Tribotherians’ (Stem Boreasphenidans)

DESCRIBER    Fox, 1980
TIME    Cretaceous Late
Santonian
CLASS    Mammalia
SUBCLASS    Boreasphenida
ORDER    Aegialodontidae
FAMILY    Picopsidae
FOSSILSITE    Milk River Formation, Alberta, Canada
INFO

Upper molars longer anteroposteriorly than transversely, whitout enterior stylar shelf and stylocone, wery little of no ectoflexus, mesostyle present, paracone higher than metacone, small protocone, no conules and no precingulum (weak postcingulum present). Attributed lower molar is represented only by the trigonod, with bladelike anteriorly placed paraconid, and reduced posterior metaconid.