Amphicynodon typicus ( Schlosser, 1888 )

Bonis, Louis de, Gardin, Axelle & Blondel, Cécile, 2019, Carnivora from the early Oligocene of the ‘ Phosphorites du Quercy’ in southwestern France, Geodiversitas 41 (15), pp. 601-621 : 603

publication ID	https://doi.org/ 10.5252/geodiversitas2019v41a15
publication LSID	urn:lsid:zoobank.org:pub:9DD3CC29-3AEA-44B8-8E8F-6AD882DF5B1C
DOI	https://doi.org/10.5281/zenodo.3703499
persistent identifier	https://treatment.plazi.org/id/03A48799-1A64-FF9A-FF43-FB9B6AA4FD5C
treatment provided by	Valdenar
scientific name	Amphicynodon typicus ( Schlosser, 1888 )
status

Treatment

Amphicynodon typicus ( Schlosser, 1888)

( Fig. 1B View FIG )

TYPE SPECIMEN. — Neotype by designation ( Cirot & Bonis [1992: 121]): left hemi-mandible with p4-m2 UP PC46 from Pech Crabit, MP 23 .

NEW MATERIAL. — Left-hemi-mandible UP VAL2; right hemimandible with m2 UM VD 13.

DESCRIPTION

The left hemi-mandible UP VAL2 ( Fig. 1B View FIG ) preserves the tooth series p2-m3. The corpus is elongate with a convex lower border. The ascending ramus and the distal part of the mandible are broken off, leaving only the rostral part of the masseteric fossa. The teeth are unworn; the single-rooted p1 is missing. The p2 is asymmetric, the distal portion being very elongate, p3, separated by a short diastema, is larger and less asymmetric. The p4, the least asymmetric premolar, is tall, and pointed with a pacd and the base of the crown slightly upturned mesially and distally.

A faint cingulid underlines the base of the buccal side of m1; the protoconid, higher than the p4, is slightly bucco-lingually compressed; the paraconid, set slightly obliquely, extends the shearing blade of the trigonid; the conical, reduced metaconid is not visible in buccal view; a relatively short talonid displays a large and compressed hypoconid and a very low entoconid, in contact at their bases, creating a V-shaped talonid basin although most of the surface is occupied by the sloping lingual face of the hypoconid. This structure is seen in A. typicus .

The protoconid and metaconid of m2, the former being slightly the larger, enclose a well-developed mesial fovea. The distal fovea, enclosed by the hypocristid and entocristid, is more elongate. The buccal portion of m3 is partially broken off, the tooth seems to have had a circular flat basin enclosed by a swollen cristid.Two main characters present in UP VAL2 and A. typicus are the pointed p4 and the trenchant talonid of m1. They seem sufficient to allow us to place the specimen in this species.

The hemi-mandible UM VD13 is shallow and includes fragments of the roots of p3 and p4, alveoli of m1, m3 and an unworn m2. Its outline tapers distally. The preprotocristid of a well-developed protoconid runs to a tiny mesio-lingual bulge corresponding to the paraconid, which is separated by a notch from the metaconid. The latter, as high as the protoconid, is followed directly by the postmetacristid to join a globular hypoconid, enclosing a small but deep talonid basin. The trigonid occupies 2/3 of the crown.