Fig. 44. Milk dentition, genus and species?—
natural size.
Specimen 3142 gen. and sp.?
This specimen is the mandible with the milk dentition. The molars present suggest Prosotherium triangulidens, but inc. 3 and the canine are present, and the first two incisors are not enlarged, so it would seem to represent a genus which I have not been able to identify. Molar 1 is bilobed and similar to that of Prosotherium. The deciduous premolars are all present, all rooted, and all remarkable for their great antero-posterior elongation. Roots of the incisors and canine are present, that of the canine being the largest, and those of the incisors being about equal in size. This would suggest such a form as Protypotherium, were this genus represented in the Deseado beds.
Interatheriidae
The family is characterized by the incisors not being enlarged, by upper and lower premolars and molars being inflexed on both the inner and out sides, and by the inflated mastoid bulla being filled with cancellous tissue. The only genus referable to this family, from the Deseado beds, is Archaeophylus.
Archaeophylus Ameghino
Archaeophylus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 423.
The genus is based on a skull which preserved most of the upper dentition except the incisors, and which shows the characteristics of the family in their inception.