Protadelomys sp.

Vianey-Liaud, Monique & Hautier, Lionel, 2022, Revision of the genus PRotadelomYS, a middle Eocene theridomyoid rodent: evolutionary and biochronological implications, Swiss Journal of Palaeontology (8) 141 (1), pp. 1-98 : 40

Protadelomys sp. indet

Material. Two specimens from Egerkingen [Ek 250, p4–m2 ( Fig. 10b ) and He 6, m2 ( Fig. 10c )] differ from P. cartieri in the anteroconid more buccally positioned, the more mesial lingual metalophulid I, and the occurrence of a mesoconid. Tey also differ from P. lugdunensis in the weaker and mesiodistally oriented distal ectolophid, making the sinusid shallower buccolingually, and more symmetrical.

Description

p4. Ek 250. Tis tooth is slightly shorter than m1. Te high metaconid is mesial, the postmetacristid high and long, the protoconid very low and hardly distinct from the postprotocristid and the ectolophid. Te ectolophid interrupts in front of the hypoconid. Te prehypocristid is absent and the entolophid ends free buccally. Tere is a shallow notch between the post-hypocristid and the hypoconulid, which connects the posterolophid. Te posterolophid joins the entoconid, closing the posterosynclinid lingually. Several extra-ridges qre visible in the talonid basin, the main ridge being more or less mesiodistal.

molars. Ek 250 and He 6. On EK250, the m1 is shorter and narrower than the m2, its protoconid–metaconid width being lower than the hypoconid–entoconid width. Te m1 and m2 have a low bulbous anteroconid. Te anteroflexid opens buccally and closes lingually due to the contact of the anteroconid against the lingual metalophulid I (= premetacristid). Te lingual metalophulid I is double on the m2 Ek 250: a mesial thick and short part is observable on the three teeth, to which a short and low more distal lophid is added, oriented mesiolingual to distobuccal on the m2 Ek 250. On the m1 and m2 of Ek 250, a short mesiodistal ridge is joining the buccal metalophulid (on m2) or parallel to it (on m1); it is absent on He 6. Te postprotocristid is oblique and thick, longer in Ek 250 than in He 6. Te mesial ectolophid is poorly individualized and short; it is weakly separated from the mesoconid on m1. A weak ectomesolophid is present on He 6 and on the m1 Ek 250. Te distal ectolophid is short, lower than the short prehypocristid. On these two specimens, the attachment of the entolophid varies. It is more mesial and located at the junction ectolophid–prehypocristid or a little more distal on Eg 250 m 1–m2. In He 6 the entolophid is angled, it is transverse in Ek 250. Te entoconulid is bulged on the m1 Ek 250 and the m2 He 6. Te posterolophid is long and joins the entoconid.

Figures

Fig. 10 a Lower tooth row of Protadelomys cartieri (Stehlin & Schaub, 1951), from Egerkingen (Swiss Jura); Ek 248,left p4–m3; a1, m2–m3, occlusal view; a2, p4, first, occlusal view, second buccal aspect; third, lingual aspect. b Lower tooth row, Protadelomys sp. indet., from Egerkingen (Swiss Jura); Ek 250, left p4–m2; b1, occlusal view;b2, buccal aspect; b3, lingual aspect. Scale bar=1 mm