Matthodon peignei, 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 : 187-190

Matthodon peignei n. sp.

( Fig. 1 )

urn:lsid:zoobank.org:act:F79F2003-3B67-466B-AA9E-03F94442912F

HOLOTYPE. — UM-AUM694 , left mandible with p2-m3 and the alveoli for the canine and p1.

ETYMOLOGY. — Dedicated to the memory of Dr. S. Peigné (1972- 2017), who described numerous carnivorous mammals from the Paleogene and Neogene of Eurasia and Africa.

REFERRED SPECIMENS. — UM-AUM268, left mandible with m2 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.

DIAGNOSIS. — Matthodon peignei n. sp. is intermediate both metrically and morphologically between Matthodon menui and Matthodon tritens: M. peignei n. sp. differs from M. menui by having longer premolars and molars and from M. tritens by having mesiodistally shorter premolars and molars. Matthodon peignei n. sp. differs from M. tritens by having less developed paraconids on p2, p3 and p4; the larger and more individualized metaconid on the molars; the longer talonid on the m1 and m2; and by shorter molars (4% for the m1, 8% for the m2 and m3), and longer p2 and p4 (respectively 9% and 5%). Matthodon peignei n. sp. differs from M. menui and M. tritens by the relative larger size of the p2, and narrower premolars.

MEASUREMENTS. — Table 1.

DESCRIPTION

UM-AUM 694 is almost a complete mandible that bears well-preserved teeth, except the i3, canine and p1, which are represented by their alveoli ( Fig. 1 A-C). The mandible is deep (26.3 mm below the m1). Two mental foramina are present: the first one opens below the posterior root of p2, while the second is present below the anterior root of p4. The masseteric fossa is very deep. A deep fossa for insertion of the temporal muscle is present along the anterior margin of the crest. The angular process is curved sharply dorsally and is relatively wide. The mandibular condyle is robust, and is mediolaterally wide. The presence of an incisor (possibly the i3) is indicated by its tiny alveolus in front of the canine. The canine is buccolingually wide. The canine, premolars and molars are very close together. The p1 is single-rooted. The teeth display crenulated enamel.The p2 is simple with only the hypoconid present on the talonid. A small fold indicates the position of the paraconid. The p3 is mesiodistally longer and buccolingually wider than the p2. It differs by the presence of a paraconid, and by having three cuspids on the talonid: the larger corresponds to the hypoconid, while the other two are situated in the position of the entoconid. The p4 is more symmetrical in lateral view than the p3. The paraconid is much more developed. On the talonid, two cuspids are present: the hypoconid and the entoconid, which form a postfossid. The three molars display similar morphologies. The m3 is slightly mesiodistally shorter than the m2, but this is due to the reduction of the talonid. The paraconid is prominent and located mesially. The anterior keel is well developed. The metaconid is lower than the paraconid and almost completely fused with the protoconid. The latter is distinctly the highest cusp. The talonid is mesiodistally short and narrow. The postfossid is narrow and surrounded by three bulbous cusps: entoconid, hypoconid and hypoconulid; the entoconid being the tallest one. The m3 differs from m1 and m 2 in having a much more reduced talonid in which the talonid cusps can- not be distinguished. The precingulid is short (limited to the paraconid) but is very wide, notably on m3.

DISCUSSION

The new fossils share with Matthodon species the peculiar distal positions of the mental foramina (the first is inferior to the distal margin of p1 and the second is inferior to p4), the presence of a single-rooted p1, a closely packed toothrow, and the poorly developed metaconid on molars. All these features distinguish Matthodon from the European Ypresian and Lutetian hyaenodonts. UM-AUM694 is among the best preserved mandibles ever found for Matthodon .

The genus Matthodon is represented by two species: Matthodon menui from Chavot, Monthelon, Mancy, and Grauves (Ypresian, MP10; France) and Matthodon tritens from Geiseltal- Untere Unterkohle (Lutetian, MP11; Germany).

The fossils from Aumelas differ from those of the Lutetian species, Matthodon tritens, by having less developed paraconids on p2, p3 and p4; the larger and more individualized metaconid on the molars; the longer talonid on the m1 and m2; and by shorter molars (4% for the m1, 8% for the m2 and m3), and longer p2 and p4 (respectively 9% and 5%). These differences are reminiscent of the Ypresian species Matthodon menui.

The fossils from Aumelas, are distinct from those referred to Matthodon menui by having longer premolars and molars: the molars are 6% longer, the p2 9% longer, and the p3 and p4 4% longer. The mesio-distal diameter of the alveolus of the p1 is also distinctly longer than those measured for M. menui. As indicated above, the teeth from Aumelas are morphologically more similar to those of M. menui than to those of M. tritens.

The mean width/length ratio of the p2, p3 and p4 differentiates Matthodon peignei n. sp. from M. menui and M. tritens by having narrower premolars ( Table 2).

The fossils from Aumelas appear intermediate both metrically and morphologically between Ypresian M. menui and Lutetian M. tritens. It differs from the two previously described taxa by the relatively large size of the p2. This feature is highly characteristic because the relative size of the p2, which decreases from M. menui to M. tritens, can be considered as an indication of the reduction of the anterior dentition (p1 and p2). The larger size of the p 2 in UM/AUM 694 thus can be regarded as a primitive feature. The same observation can be made for the narrowness of the premolars.

Based on these comparisons the Aumelas specimen represents a new species of Matthodon , the first occurrence of the genus in the southwestern part of Europe.

Figures

FIG. 1. — Matthodon peignei n. sp. from Aumelas (MP10-MP11?): A-C, UM-AUM694 (Holotype), left mandible bearing the p2-m3 and the alveoli of the canine and p1; A, occlusal view; B, lingual view; C, labial view; D-F, UM-AUM268, left mandible bearing the m2 and m3; D, occlusal view; E, lingual view; F, labial view. Scale bars: 1 cm.