Although it has the deciduous dentition, Mme Pavlow considers herself justified in referring the Kherson skull to the genus Procamelus previously known only from the Lower Pliocene or Upper Miocene strata of North America, and differing from modern camels, among other features, by the retention of a fuller series of premolar teeth.
The Dipodinae, on the other hand, are leaping rodents, with the metatarsals elongated, a small upper premolar present or absent, and the crowns of the molars tall.
Next to the latter is a curved, sub-erect canine, followed after an interval by an isolated minute and often deciduous simple conical premolar; then a contiguous series of one premolar and three molars, which differ from those of recent species of Camelus in having a small accessory column at the anterior outer edge.
The last premolar and the molars have quadrate crowns, provided with two strong transverse ridges, or with four obtuse cusps.
As regards the teeth, canines are wanting, and the penultimate upper premolar is short, from before backwards, with a distinct ledge on the inner side.
Distinctive feature of the genus is the great fore-and-aft length of the penultimate premolar in both jaws.
Choeropotamus is a European Oligocene genus with bunodont molars which show a conspicuous basal cingulum in the lower dentition; the first premolar is absent.
The next stage is Helaletes, also of Middle Eocene age, in which the first lower premolar has disappeared, and the last two upper premolars have become molar-like.
In some respects intermediate between the preceding and the next genus is Dasyuroides byrnei, of Central Australia, an animal of the size of a rat, with one lower premolar less than in Phascologale, without the first hind toe, and with a somewhat thickened tail.
The least specialized genus is Zapus, containing the jumping-mice of North America, with one outlying Siberian species, in which the five metatarsals are free, as are also the cervical vertebrae, the small upper premolar being retained.