Leonhardtina meridianum, Solé & Marandat & Lihoreau, 2020

Solé, Floréal, Marandat, Bernard & Lihoreau, Fabrice, 2020, The hyaenodonts (Mammalia) from the French locality of Aumelas (Hérault), with possible new representatives from the late Ypresian, Geodiversitas 42 (13), pp. 185-214 : 192-194

Leonhardtina meridianum n. sp.

( Fig. 3 )

urn:lsid:zoobank.org:act:DA2667CF-BFAD-4CFD-AFE0-E9B1416140D2

HOLOTYPE. — UM-AUM54 , right mandible bearing p3 to m3.

ETYMOLOGY. — Meridianum (Latin) means from the Midi, the south. In reference to the fact that the species is recorded only in the southern part of France.

REFERRED SPECIMENS FROM AUMELAS. — UM-AUM530, right maxillary fragment bearing M2 and M3.

OTHER REFERRED SPECIMENS. — MNHN.F.RZ142, right mandible bearing p2-p4 and m3 .

HORIZON AND AGE. — Lacustrine limestone of Montpellier, proposed as Lutetian in age in previous study but here considered possibly late Ypresian/early Lutetian in age

TYPE LOCALITY. — Aumelas, Hérault, France.

OTHER LOCALITY. — Rouzilhac, Aude, France (Ypresian-Lutetian?; MP10b, Godinot et al. 2018)

DIAGNOSIS. — The new species is smaller than Leonhardtina godinoti (5% based on the length of the molars) and Leonhardtina gracilis (20%). It also differs from these species by a narrower postfossid on molars, and by relatively larger p3 relative to p4.

MEASUREMENTS. — Table 4.

DESCRIPTION

The upper teeth are represented by the M2 and M3 ( Fig. 3A, B ). The M2 is characterized by the separation of the paracone and metacone. These cusps appear to be of similar height. The parastyle is well-developed. The metastyle is long and mainly buccally aligned. The protocone is extended buccolingually and mesiodistally short. The protofossa is worn. The M3 is buccolingually elongated. The parastyle is long. Only the paracone is visible; the metacone-metaconule area is broken. The protocone is almost as tall as the paracone. A paraconule is discernable.

The mandible is deep ( Fig. 3C, D ). The coronoid crest is slightly distally inclined; the angle between the coronoid crest and the body of the dentary is close to 100°. As in the two other hyaenodonts from Aumelas, a deep fossa for the insertion of the temporal muscle is present along the anterior margin of the coronoid crest.

The p3 is elongated mesiodistally and is longer than the p4 ( Table 4). The tooth is too damaged to describe its morphology ( Fig. 3 F-H). The p4 probably had a paraconid, but the anterior part of the tooth is too damaged to be sure. The protoconid is robust. The talonid is short in length and bears two cusps: a hypoconid and a lingually located entoconid. The molars are similar in morphology except the m3 has a narrower and more mesiodistally elongated talonid than m1 and m2 ( Fig. 3 F-H). The three teeth have a sharply pointed and mesiodistally compressed trigonid. The paraconid is lingually located relative to the protoconid. The metaconid is buccolingually aligned with the protoconid. The apexes of the metaconid and paraconid are worn preventing comparison of cusp height; the paraconid was however probably shorter in height than the metaconid. The talonid is almost as wide as the trigonid. The postfossid is narrow. The three talonid cusps are well individualized and bulbous. The talonid is labially oriented relative to the horizontal ramus as in primitive hyaenodonts (e.g., Prototomus, Eoproviverra). The hypoconulid is slightly taller than the two other talonid cusps. The hypoconulid and entoconid are close together. On the molars, the three talonid cusps are well-defined. The precingulid seems to have been present as well as an incipient postcingulid, but this is uncertain due to taphonomic processes. No ectocingulid is present.

DISCUSSION

The fossils of Leonhardtina meridianum n. sp. described differ from those of Matthodon and Oxyaenoides by their smaller size; the p3 longer than the p4; the wide talonid on the molars; and the sharply pointed and mesiodistally compressed trigonid of the molars.

According to our phylogenetic analysis (see below), Leonhardtina is closely related to Preregidens langebadrae. This latter species is only represented by one mandible discovered at Saint-Papoul (MP8+9; France) ( Solé et al. 2015a). Preregidens shares with Leonhardtina the presence of mesiodistally short trigonid and buccolingually narrow postfossid on molars. However, Preregidens differs from L. gracilis and L. meridianum n. sp. by having buccolingually narrower talonid on molars, the absence of postcingulid on molars, shorter talonid on m3, and possibly the p3 shorter than the p4 (the p3 is only represented by its alveoli on the sole known fossil of Preregidens). Preregidens also differs from L. gracilis by having a higher and sharper p4.

The p3 longer than the p4, the wide talonid on the molars, and the sharply pointed and mesiodistally compressed trigonid of the molars are features that characterize the small hyaenodonts Leonhardtina, Proviverra, Lesmesodon, and Allopterodon , which form a clade in Solé et al. (2014a, 2015a). This clade is not recovered in the recent analyses (e.g., Borths & Stevens 2017c, 2019) nor in the phylogenetic analysis we performed ( Fig. 4 ).

Leonhardtina meridianum n. sp. differs from Proviverra, Lesmesodon and Allopterodon by having weakly developed labial cingulids on the p4 and the molars; the latter are indeed well-developed in the three European hyaenodontoid genera, notably Proviverra (Lange-Badré 1981; Morlo & Habersetzer 1999). Leonhardtina further differs from these genera by having more oblique cristid obliqua, and narrower talonids and postfossids on the molars.

Some species of the genera Cynohyaenodon, Paracynohyaenodon, and Quercytherium are also close in size to Leonhardtina . However, these genera clearly differ from Leonhardtina by the p3 shorter than the p4 and a mesiodistally elongated trigonid on molars. These features also distinguish Leonhardtina from Boritia, a monospecific genus phylogenetically close to Cynohyaenodon, Paracynohyaenodon, and Quercytherium.

The weakly developed labial cingulids on the molars are also found in late Ypresian and early Lutetian genus Leonhardtina . This genus is represented by two species: L. godinoti from Grauves (Ypresian, MP10; Solé et al. 2014a) and L. gracilis from Geiseltal-Untere Mittelkohle and Geiseltal-Obere Mittelkohle (Lutetian, MP12-13; Matthes 1952; Lange-Badré & Haubold 1990). The fossils from Aumelas are smaller than other Leonhardtina species: 5% smaller than L. godinoti and 20% smaller than L. gracilis. The newly described fossils are 15-20% larger than those of Proviverra typica, which is found with L. gracilis in Geiseltal (Lange-Badré & Haubold 1990).

The new fossils also differ from the two species of Leonhardtina by having a relatively larger p3. The ratio of p3 length to p4 length equals 1.21 for L. meridianum n. sp. The ratio equals 1.04 in L. godinoti and 1.08 in L. gracilis. However, the ratio in L. meridianum n. sp. may be overestimated because the p3 and p4 are crushed, which probably results in lengthening the p3 measurement.

Godinot et al. (2018) described a mandible discovered in the locality of Rouzilhac (Aude, France; MP10b) that they referred to Leonhardtina cf. gracilis. The teeth preserved on the mandible are very close in size to those preserved on UM-AUM54 ( Table 4). Moreover, the p4 and m3 are morphologically identical (e.g., talonid mesiodistally compressed on m3). Because of these similarities, we propose that MNHN.F.RZ142 and UM-AUM54 belong to the same taxon.

The p3 and p4 are better preserved on the fossil from Rouzilhac: the ratio p3 length/p4 length equals 1.3 in this specimen. This is consistent with L. meridianum n. sp. having a relatively large p3 compared to L. godinoti and in L. gracilis.

L. meridianum n. sp. differs from the other Leonhardtina species by having narrower talonids and postfossids and a more oblique cristid obliqua on the molars. The morphology of the talonids of the molars on UM-AUM54 are similar to the earliest European hyaenodonts such as Eoproviverra (Rians; Ypresian, c. MP7) and Parvagula (Palette, Fournes, Fordones; Ypresian, c. MP7) rather than Leonhardtina, Allopterodon or Proviverra.

The upper teeth (M2 and M3) are poorly preserved and not very diagnostic. However, they are morphologically similar to those of Leonhardtina gracilis in having a separated paracone and metacone; a buccally aligned metastyle; and a lingually elongated protocone.

To conclude, the Leonhardtina species found at Aumelas is smaller than the two Leonhardtina species known in northwestern Europe, and has the potentially primitive feature of a narrower talonid and postfossid on molars. However, L. meridianum n. sp. has the potentially derived feature of a relatively long p3.

Figures

FIG. 3. — Leonhardtina meridianum n. sp. from Aumelas (MP10-MP11?): A, B, UM-AUM530,right maxillary fragment bearing M2 and M3; A, occlusal view; B, labial view;C-H, UM-AUM54 (Holotype),right mandible bearing p3 to m3; C, lingual view; D, labial view;E, occlusal view; F, occlusal close-up; G, lingual close-up; H, labial close-up. Abbreviations: me, metacone; pa, paracone; pr, protocone. Scale bars: 1 cm.

FIG. 4. — Results of the phylogenetic analysis of Hyaenodonta character-taxon matrix. Results are visualized as an “all compact” (majority rule plus compatible groups) consensus tree. Major, named clades recovered or discussed in this analysis and recovered in other analyses are illustrated. In bold: new hyaenodonts species described herein.