Coniopternium Ameghino
Coniopternium Amegh., 1895 Bol. Inst. Geog. Argen., t. 15, p. 632.
Coniopternium Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 453.
The genus is based on a calcaneum and astragulus of the macrauchenid type, but of unusually large size. The real generic characters are not evident in the description, but the presence of these bones, and of three cervical vertebrae, which we also found, indicating a macrauchenid of about the same size, are evidence that a form larger than the Santa Cruz representatives will turn up in the Deseado beds, for which this name may be reserved. The material is described under the specific name C. andinum.
Adianthidae Ameghino
This family is based primarily on the genus Adianthus of the Santa Cruz to contain some macrauchenid-like forms which, however, are of much smaller size, and differentiated by the narrow character of the teeth and their early tendency to hypsodonty. It seems to be a valid series of dwarf types, which are all scarce and known only by the most fragmentary remains. Two genera are described from the Deseado, Tricoelodus, peculiar in having the posterior lobe of the lower molars somewhat subdivided so that the tooth appears three-lobed; and Proadianthus, known only by premolars which however show an unusual development of the styles on the inner side of the teeth.
Tricoelodus Ameghino
Tricoelodus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 454.
The genus is based primarily on the three-lobed character of the molars, which is a secondary effect of an infolding on the inner side of the posterior lobe. They are rooted, but strongly hypsodont. The margins of the crescents are well developed and the “pillar” is a prominent feature in the posterior crescent.
Tricoelodus bicuspidatus Ameghino
T. tricuspidatus Amegh., loc. cit. above.