Geotrypus Pomel, 1848

Vianey-Liaud, Monique, Comte, Bernard, Marandat, Bernard, Peigné, Stéphane, Rage, Jean-Claude & Sudre, Jean, 2014, A new early Late Oligocene (MP 26) continental vertebrate fauna from Saint-Privat-des-Vieux (Alès Basin, Gard, Southern France), Geodiversitas 36 (4), pp. 565-622 : 576-577

Genus cf. Geotrypus Pomel, 1848 ( Fig. 3B )

TYPE SPECIES. — Geotrypus acutidentatus de Blainville, 1840 by subsequent designation of de Blainville (1840).

MATERIAL EXAMINED. — SPV 800-802: one complete lower molar (m1ṙ: L = 2.16, Ltrig. = 1.09, Ltal. = 1.08, wtrig. = 1.35, wtal. = 1.58), and a broken lower molar (m2ṙ), both weakly worn out and one lower premolar.

DESCRIPTION

Ŋe complete molar is probably an m1, the talonid being wider than the trigonid. Ŋe other trigonid being still wider, it would be that of an m2. Cuspids are high.Ŋe hypoconid is as high as the protoconid. Ŋe paraconid is twice as high as the metaconid, and it has the same height as the entoconid. Seen in lingual profile, the metaconid is almost cylindrical, sharper only at the top. Ŋe lingual profile of the entoconid is more conical than the metaconid, but with a relatively narrow base and an acute angle at the top. Ŋe postcristid is directly and transversely connected with the entoconid. Ŋere is no preentocristid. A strong entostylid can be seen near the end of the very low posterior cingulum. It then extends to the lingual surface of the tooth more or less continuously, by a weak cingular bulge dotted with more or less distant vertical crestules, to join the anterior cingulid. At the lingual base of the crown the collar is rectilinear.

Ŋe anterior cingulid extends labially and disappears at the base of the protoconid. Labially a weak and very low cingulum limits the base of the hypoflexid; it does not extend to the base of the hypoconid.

DISCUSSION

Ŋese specimens show similarities with Geotrypus (cusps very slender, somewhat lingually oblique ridge joining the base of the posterior trigonid wall, entocristid reduced or absent, anterior cingulum developed; Crochet 1995). However, a number of differences prevent its attribution with certainty to that genus. Ŋe lingual cusps are more slender than those of Geotrypus cf. acutidentatus (de Blainville, 1840) from Le Garouillas (Lot, Quercy, MP 25). Ŋe teeth from Saint-Privat-des-Vieux differ from those of this species and also from Geotrypus antiquus (de Blainville, 1840) from Pech du Fraysse (MP 28) by their larger size and especially their width. Ŋey also differ from these two species in having longer cingulid, smaller parastylid and stronger entostylid, a small difference in height between protoconid and hypoconid and the development of a very low and discontinuous labial cingulid. Ŋe lingual base of the crown is in the same vertical plane while it is concave at the opening of the trigonid in G. antiquus . It shares with these two species the well cuspidate paraconid, the high labial elongation of the anterior cingulid, and with G. cf. acutidentatus the absence of entocristid. It differs from the type of Myxomygale (Filhol, 1890) by the absence of entocristid and metastylid, and the crista obliqua ending less lingually.

Figures

FIG. 3. — Saint-Privat-des-Vieux (Gard, Lower Chattian, MP 26): A, SEM view of a fragment of Krokolithes sp. SPV750; B-H teeth of mammals: B, cf. Geotrypus sp. SPV800, left m1, occlusal view; C-I, Cuvierimops sp.: C, SPV810, left p4-m1, labial view; D, SPV814, left m3: D1, occlusal view, D2, distal view; E, SPV812, left m2: E1, occlusal view, drawing, E2, occlusal view SEM, E3, distal view; F, SPV815, right upper canine: F1, occlusal view, F2, lingual view, F3, labial view; G, SPV820, right M3, occlusal view; H, SPV816, left M1: H1, occlusal view, H2, lingual view; I, SPV817, right M2: I1, occlusal view, I2, lingual view. Scale bars:A, 167 µm; B-I2, 1 mm.