Protadelomys alsaticus (Hartenberger, 1969)

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 : 41-43

? Protadelomys alsaticus (Hartenberger, 1969)

Remarks

On the bases of the observation of “two upper jaws” of the Naturhistorisches Museum Basel, Hartenberger (1969, p.46) wrote that the M2 are stronger than the M1, their posteroloph being longer on M2. For this reason, he assigned the specimen BUX 67–2 (Te holotype) to an M1. However, on this specimen, the metacone–hypocone width is reduced compared to the paracone–protocone width, and the posteroloph is short, like for the M2 of the species of Protadelomys ( P. cartieri or P. lugdunensis ) and more generally of the basal Teridomorpha. Te holotype rather represents an M2. Moreover, the size distribution (L x w) of the M1 overlaps that of M2

( Fig. 27A and Table 4), which indicates that M2 are not typically larger than M1. Furthermore, the two specimens from the NHMB (Buchs 660) are for one an upper jaw with M1–M3 and the other one a lower jaw with p4–m2. Tey are not “ two upper jaws with P4–M1–M2 ” (Hartenberger, 1969: 46) .

Holotype. M2 (not M1) sup. (Hartenberger, 1969: PI. 2, Fig. 6 ; this paper: Fig. 31a ).

Type locality. Bouxwiller (green marls), France; middle Eocene, MP 13.

Original diagnosis (translation from French). “ Protadelomys more primitive than P. cartieri . Upper molars with sinus less pronounced. Paraconule, metaconule, and mesostyle variable in volume. Short lower fourth premolars. Numerous wrinkles.”

New diagnosis. Dental morphology “intermediate” between Masillamys and Protadelomys . Unilaterally weakly hypsodont teeth; almost the entire teeth bear more or less low extra-ridges and granules, and enamel surface of the outskirts of the crown (mainly lingual for upper teeth or buccal for lower teeth) displaying faint and oriented ornamentations from the base to the edge of the crowns.

Upper teeth: DP4 a little smaller than P4 and more molarized, with the hypocone lingually displaced. P4 with paracone and metacone more bulbous than on DP4; paraconule mesially displaced and fused with the anterostyle; small hypocone variably present. On molars, the hypocone is slightly smaller, to nearly equal in size, than the protocone. Te M2 posterior width is shorter than the M1 posterior width. Te postparacrista and premetacrista variably present. Te mesostyle is always present; the mesoloph sometimes reaches the mediobuccal ridge of the metaconule. A small hypocone is generally present on M3.

Lower teeth: the anteroconid is buccally located on molars; it is more or less lingually stretched, and sometimes joins the linguobuccal premetacristid. Te anterocingulid is absent. Te mesial metalophulid I often corresponds to the premetacristid, which sometimes bifurcates or is parallel to a more distal branch of the metalophulid I. Te latter sometimes turns distally to join the buccal transverse branch of the metalophulid I. Te postprotocristid is thick, long and oblique; its distal end is often swollen with a premesoconid spur. Te short mesiodistal ectolophid bears a small mesoconid. Te ectomesolophid and mesolophid spurs are variably developed or absent; the postmesoconid swelling and/or spur is present and variably developed. Te entolophid lowers buccally, and attaches either to the postmesoconid spur/swelling or to the junction of the distal part of the ectolophid and the prehypocristid, which is short. Te hypoconulid is bulged and sometimes duplicated.

Figures

Fig. 27 Bivariate graph of the size (width/length) of the upper (A) and lower (B) teeth of?Protadelomys alsaticus Hartenberger, 1969 from Bouxwiller (Bas-Rhin) (dp4/DP4 and p4/P4: red marks; upper and lower molars: black marks). From Bouxwiller, a few teeth are identified as?P. cf. alsaticus sp. indet 1 (purple marks), sp. indet 2 (turquoise blue marks) and sp. indet 3 (green marks). On B, four teeth (orange marks) are Masillamys parvus from Messel (Germany)

Fig. 6 Upper teeth of Protadelomys cartieri (Stehlin & Schaub,1951), from Egerkingen (Swiss Jura). a Ek H005, right upper tooth row,P4–M1–3; a1, occlusal view; a2, lingual aspect of M1–P4; a3, buccal aspect of P4–M1–3. b Eg 601, left upper tooth row, P4–M2, occlusal view. c: Ek H006, right upper tooth row, P4–M2; occlusal view, teeth worn.Scale bar: 1 mm

Fig. 31 Upper M2 of?Protadelomys alsaticus Hartenberger, 1969 from Bouxwiller (Bas-Rhin). a BUX67-2, left M2, Holotype; a1, occlusal view; a2, lingual aspect; a3, buccal aspect. b CH43, right M2; b1, occlusal view;b2, lingual aspect. c: CH41, left M2; c1, occlusal view, c2, lingual aspect; c3, buccal aspect. d CH32, left M2; d1, occlusal view; d2, lingual aspect. e BUX67-44, left M2; e1, occlusal view; e2, lingual aspect; e3, buccal aspect. f CSBX69, left M2; occlusal view. g CSBX33,right M2; occlusal view.h BUX67-6, right M2; occlusal view.i BUX67-56, left M2; i1, occlusal view; i2, lingual aspect; i3, buccal aspect. j: BUX67-72, left M2; j1, occlusal view; j2, lingual aspect; j3, buccal aspect. k: BUX67-52, left M2; k1, lingual aspect; k2, occlusal view; k3, buccal aspect. l: BUX67-79, left M2; occlusal view. Scale bar: 1 mm