Ambondro mahabo

Ambondro mahabo.
Ambondro mahabo is a mammal from the middle Jurassic (about 167 million years ago) of Madagascar. The only species of the genus Ambondro, it is known from a fragmentary lower jaw with three teeth (pictured), interpreted as the last premolar and the first two molars. The premolar consists of a central cusp with one or two smaller cusps and a cingulum (shelf) on the inner, or lingual, side of the tooth. The molars have a similar cingulum, three cusps at the front, and a talonid with a main cusp, a smaller cusp, and a crest at the back. Features of the talonid suggest that Ambondro had tribosphenic molars, the basic arrangement of molar features also present in marsupial and placental mammals. It is the oldest known mammal with putatively tribosphenic teeth; at the time of its discovery it antedated the second oldest example by about 25 million years.