From the Phascolomyidae, the two families, which may be collectively designated Phalangeroidea, differ by the circumstance that in the skull the tympanic process of the alisphenoid covers the tympanic cavity and reaches the paroccipital process.
The post-glenoid, post-tympanic and paroccipital processes of the skull are large, and there is an alisphenoid canal.
The tympanic process of the alisphenoid bone of the skull is short, not covering the cavity of the tympanum, nor reaching the paroccipital process.