The protoconid, metaconid, hypoconid and entoconid
are organized into two distinct lobes with rounded corners separated from each other by a well-developed median valley.
The lower molars, especially the m1, are close to the material from Napak I, in particular NHM M 19085 (paratype of the species), which shares the strong development of the metaconid, the barely distinguishable entoconid
that is essentially a peripheral cristid, and the overall bunodont aspect of the tooth.
The m1 has the labial and lingual cusps alignment alternate rather than opposite (as in the uppers), the metaconid is anteriorly positioned with respect to the protoconid, and the entoconid
is anteriorly positioned with respect to the hypoconid.
genovensium: greatly elongated muzzle; forearm longer that 40 mm; rostrum clearly longer than the braincase; premaxillary bones projected beyond the canines, producing a triangular projection; flat palate; "V" shaped medial posterior margin of the palate; all incisors (upper and lower) in contact; upper incisors projecting forward, almost as an extension of the rostrum; flattened lingual surface of upper canines; upper premolars longer and narrower; first upper premolar short and lacks the labial cingulum; the second upper premolar presents a weakly labial cingulum and an accessory posterior cuspid; metastyles of the upper molars are reduced; weakly trifid lower incisors; lower canines with a lingual cingulum; and entoconid
absent in all lower molars (Figs.
Number of Occurrences Percentage Tooth First molar (P) 58 62.4 Fourth premolar (D) 18 19.4 Second molar (P) 14 15.1 Second premolar (D) 6 6.5 Third molar (P) 5 5.4 Third premolar (D) 5 5.4 Cusp Hypoconid 77 55.4 Protoconid 26 18.7 Metaconid 18 12.9 Entoconid
17 12.2 DISCUSSION
Additionally, the m1 and m2 possess entoconid
The crescent-shaped lower molars are divided into an asymmetrical anterior portion (trigonid) anda longer, symmetrical posterior portion (talonid) with an isolated transverse crest representing the entoconid
. These features diagnose the specimens as members of Notoungulata (Simpson, 1948; Lavocat, 1958; Paula Couto, 1979).
The crest joins to the metaconid and incorporates the entoconid
. The entoconid
is independent from the metaconid in early wear.
geismarianus is characterized by an m I with a low, short trigonid with the metaconid slightly more posterior than the protoconid, a large talonid, subequal entoconid
and hypoconid, compressed m2 trigonid with an anterobuccal cingulid, and a very small paraconid SDSM 8640 differs from N geismarianus in that the length of the ml is not as reduced and has a lesser degree of trigonid compression on the m2.
and hypoconid are joined by a V-shaped posterior hypocristid and posterior entocristid.
The apices of metaconid and entoconid
are broken and hypoconulid is missing (Fig.
The mesolophid is connected to entoconid
. The posterotropids are well developed.