These specimens of
Yalkaparidon exhibit a melange of characters: the molars are
zalambdodont (a distinctive
tooth type also found in the marsupial mole
Notoryctes, the living placental '
insectivores'
Solenodon,
tenrecs and
golden moles, as well as a number of
fossil groups); the
incisors are very large and hypselodont (open-rooted and hence ever-growing, similar to those of
rodents); the basicranial region of the only known skull is very primitive, somewhat similar to those of
plesiomorphic bandicoots. The zalambdodont molars appear to link it to notoryctid marsupial moles, but detailed study of the teeth of these two groups suggests that they have evolved independently, and
Yalkaparidon is anatomically otherwise very different from the marsupial moles. The incisors resemble those of diprotodontians, but no other features convincingly support this relationship, and the
convergent evolution of such incisors in South American 'pseudodiprotodont' groups (such as
caenolestids and polydolopimorphians) suggests that
Yalkaparidon and diprotodontians may have evolved similar incisors independently. Basicranial similarities to bandicoots most likely represent shared plesiomorphic characters, and hence are not indicative of a close relationship. For these reasons,
Yalkaparidon is currently placed in its own
family,
Yalkaparidontidae, and
order,
Yalkaparidontia; this placement would make this the only order of Australian marsupials known to have gone extinct. However, Frederick Szalay suggested in his 1994 book 'Evolutionary History of the Marsupials and an Analysis of Osteological Characters' that
Yalkaparidon is indeed a
diprotodontian (as evinced by its incisors), albeit one that retains a highly primitive
basicranium. The exact function of its unusual
dentition remains obscure, and suggestions that it may have fed on
worms (based on the similarities of its molars to those of worm-eating tenrecs),
caterpillars or
eggs are tenuous. However, its source of food presumably had a hard outer covering (necessitating use of the large incisors) but relatively soft interior, as zalambdodont molars cannot crush food items. The possibility that it was a "mammalian woodpecker" similar to the
aye-aye and
striped possum has been raised. ==Morphology==