A single mammal, Ambondro mahabo, has recently been described (Flynn et al., 1999) from the Ambondromamy Region of the Mahajanga Basin, northwestern Madagascar (figure 2.6). Stratigraphically, the occurrence is near the top of Isalo level Illb in the Isalo "Group," and is placed in the Bathonian on the basis of a rich invertebrate fauna from this unit. A. mahabo is known by a jaw fragment with three teeth, of which the molars have a remarkably advanced, basined heel or talonid, indicating that, morphologically at least, they are of tribosphenic grade. Other features of this extraordinary animal are unlike what is encountered among "typical" early tribosphenic mammals, and we recognize it as a member of an endemic Gondwanan clade (Australosphenida) that independently acquired a complex heel on lower molars (Luo, Cifelli, and Kielan-Jaworowska, 2001, see chapter 6).

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