Also, the Chapala specimens share with Postcopemys a paraloph not aligned with the anterior arm of the hypocone in upper molars, but with the entolophid aligned with the anterior arm of the protoconid
in lower molars, and the protolophule is absent in M1.
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
The ml (MBLUZ-P-3.990, MBLUZ-P-5.896, MBLUZ-P-4.690; Table I; Figure 2f) has an anteriorly projected paraconid without enamel band; a metaconid enamel band is present; meta-entoconid fold shallow and reflected 45[degrees] anteromesialy; ento-hypoconid fold deeper and less inclined (85[degrees]) anteromesialy than meta-entoconid fold; hypoconid buccolingually broad, looks like a trigonid size; anterior facet of the trigonid convex; the lingual enamel band extends to the metaconid to the anterolingual side of the hypoconid, without covering it totally; buccal enamel fold deeper; buccal enamel band covering the anteromesial protoconid
facet through posteromesial hypoconulid facet; hypoconid lingually projected; buccal enamel broader than lingual enamel.
Ankylodon is characterized by having moderate curvature of the trigonid, reduced paraconid, strongly convex buccal margin of the protoconid
and metaconid, and boarder nature of the tooth when compared to Metacodon (1) all of which are seen in PTRM 1600.
A well developed furrow separates the hypoconid from the strong protoconid
on the buccal side.
Enamel is missing on the posterior face of the protoconid
and mesiobuccal corner of the protoconid
, and the posterior half of the hypoconid is missing.
The functional equivalent of the shearing blade and carnassial notch is the paracristid crest connecting the paraconid to the protoconid
, on the outer, anterior face of the lower molar tooth in a similar position to the eutherian carnassial blade [ILLUSTRATION FOR FIGURE 2 OMITTED].
is slightly lower than the metaconid.
The hypoconid covers more area than the protoconid
. The anterior transverse flange is present.
Well-developed labial cingulid, separated from the protoconid
The tip of the protoconid
of m1 also has a small pigmented area.