Pliolophus quesnoyensis Bronnert, Gheerbrant, Godinot & Métais, 2018

Bronnert, Constance & Métais, Grégoire, 2023, Early Eocene hippomorph perissodactyls (Mammalia) from the Paris Basin, Geodiversitas 45 (9), pp. 277-326 : 284-286

Pliolophus quesnoyensis Bronnert, Gheerbrant, Godinot & Métais, 2018

( Fig. 5 )

Pliolophus quesnoyensis Bronnert, Gheerbrant, Godinot & Métais, 2018: 239 , figs 3-7.

Hyracotherium sp. – Russell et al. 1988: 432.

Pliolophus aff. vulpiceps – Hooker 1994: 53-54, fig. 17.

“ Propachynolophus ” sp. 1 – Hooker 1994: 60, fig. 26.

Pliolophus sp. 1 – Hooker 1994: 60 (partim), fig. 26; 2010: 117 (partim).

HOLOTYPE. — MNHN-QNY2-2696 , right mandible with m1-m3 .

PARATYPES. — MNHN-QNY2-3022 , right mandible, P1 missing; MNHN-QNY2-2700 , right maxillary with P4-M3; MNHN-QNY2-2705 , right M1/2 .

MATERIAL. — Le Quesnoy: see Bronnert et al. 2018; p2 (R: MNHN-QNY2-3076) .

Meudon: mandible with p4-m3 (L: coll. Phélizon); P3 (R: unnumbered [Marseille]); M1/2 (R: MNHN-ME-16325, unnumbered [Marseille]); m1/2 (L: MNHN-ME-16322); m3 (R: unnumbered [Marseille]) .

Sinceny: P2 (R: MNHN-SY3-CN); P3 (R: MNHN-SY1-CN; L: unnumbered MNHN coll. Cahuzac); P4 (L: MNHN-SY5-DE); M1/2 (L: MNHN-SY4-DE); M3 (R: unnumbered MNHN coll. Berton). Try: DP3 (R: MNHN-M-TRY10); DP4 (R: MNHN-M-TRY3); M1/2 (R: MNHN-M-TRY23, TRY17-L; L: MNHN-M-TRY9, M-TRY11); M3 (L: MNHN-M-TRY8); p3 (R: MNHN-M-TRY16); p4 (R: MNHN-TRY22-L); m1 (L: MNHN-M-TRY5) .

TYPE LOCALITY. — Le Quesnoy (Oise, France), MP7.

DISTRIBUTION. — Le Quesnoy (Oise, France), Try (Marne), Meudon (Hauts-de-Seine, France), Sinceny (Aisne, France), MP7.

DIAGNOSIS ( Bronnert et al. 2018). — Small brachyodont perissodactyl; post-p1 diastema extremely short, almost absent; complete cheek tooth formula; sub-lophodont molars; paraconule close to protocone on P3; protocone on P2; straight centrocrista; enlarged crenulated cingulum on M3; hypoconulid lobe on m3 developed.

DIFFERENTIAL DIAGNOSIS ( Bronnert et al. 2018). — Species smaller than P. vulpiceps and P. barnesi . Differs from the latters by a straighter centrocrista and a smaller metaconule on upper molars. Further differs from P. vulpiceps by a shorter postcanine diastema.

DESCRIPTION

See Bronnert et al. (2018) for a complete description of the species. Here is only described new material.

Teeth

The P3 is nonmolariform ( Fig. 5I ). The paracone and the metacone are close, and linked by a short centrocrista. A small paraconule is present. The postprotocrista is absent. The P4 is nonmolariform and more symmetrical than the P3.The cingulum is interrupted close to the protocone. The parastyle is small and crescentiform. The paraconule is developed and anterior to the paracone. The postprotocrista extends posteriolabially to the metacone. An endoprotocrista is present posterior to the postprotocrista. There is no mesostyle on upper molars ( Fig. 5D, E , K-L). The centrocrista is straight. The paraconule is smaller than the protocone. The protoloph is slightly notched between the protocone and the paraconule. The metaconule is weak or absent. The metaloph ends by a metacone fold. The preparaconule crista joins the preparacrista. The ectocingulum is continuous. An accessory cusp is sometimes present on the cingulum between the metacone and the hypocone. The mandible is very worn and broken. The teeth are so worn that no enamel is present in occlusal view. The p2 has a single large cusp ( Fig. 5A ). On some unworn upper molars, denticules are present on the metaloph ( Fig. 5E ), and we interpreted that as intraspecific variation. A small paraconid is present. Three crest extends posterior to the main cusp. A small hypoconid is present. The p3 display a protoconid larger than the metaconid. They are closely appressed. A cristid obliqua links the protolophid to the hypoconid. The paraconid is absent. The p4 is submolariform. The protoconid is larger than the metaconid, and they are closely appressed. The hypoconid is large and linked to the protolophid by the cristid obliqua. The m1 displays a cristid obliqua oriented slightly labially. The hypolophid is formed by two crests. A transversal crest linked to the entoconid extends toward the hypoconid and this crest suddenly becomes directed toward the hypoconulid, thus forminga right angle ( Fig. 5F ). A very faint crest extends from the hypoconid toward the transversal crest starting from the entoconid and reaches the point where the latter forms a right angle. This configuration of the hypolophid is unusual in P. quesnoyensis in which the hypolophid is generally formed by a transversal crest joining the hypoconid

Deciduous teeth

The DP2possesses a large paracone,much larger than the metacone ( Fig. 5H ). The parastyle is small.There is neither protocone nor hypocone, but a developed cingulum is present on the anteriolingual margin. The DP3 displays a larger parastyle ( Fig. 5M ). There is no metaconule nor paraconule.The hypocone is larger than the protocone. The cingulum is interrupted close to the hypocone. The DP4 has a protocone larger than the hypocone ( Fig. 5N ). A small paraconule and metaconule are present. The centrocrista is straight. The cingulum is continuous.

Figures

FIG. 5. — Teeth of Pliolophus quesnoyensisBronnert,Gheerbrant,Godinot & Métais,2018 from Le Quesnoy,Try,Meudon and Sinceny:A, left p2 (MNHN-QNY2-3076); B, left p3 (MNHN-TRY16); C, left p4 (MNHN-TRY22-L); D, right M1/2 (MNHN-M-TRY23 [reversed]); E, left M3 (MNHN-M-TRY8); F, left m1 (MNHN-M-TRY5 [reversed]); G, left m1/2 (MNHN-ME16322 [reversed]); H, right DP2 (MNHN-SY3-Cn [reversed]); I, right P3 (MNHN-SY1-Cn [reversed]); J, left P4 (MNHN-SY5-DE); K, left M1/2 (MNHN-SY4-DE); L, right M1/2 (MNHN-ME16325 [reversed]); M, right DP3 (MNHN-M.TRY10 [reversed]); N, right DP4 (MNHN-M.TRY3 [reversed]); O-P, left mandible with p4, m2-m3 (coll. Phélizon); A-O, occlusal views; P, mesial view; A-N, coated with magnesium; H-K, casts. Scale bars: 5 mm.