Carnivora from the early Oligocene of the ‘ Phosphorites du Quercy’ in southwestern France
Author
Bonis, Louis de
Palevoprim: laboratoire de Paléontologie, Évolution, Paléoécosystèmes, Paléoprimatologie, Bâtiment B 35 TSA 51106, 6 rue Michel Brunet F- 86073 Poitiers cedex 9 (France)
louis.debonis@univ-poitiers.fr
Author
Gardin, Axelle
Palevoprim: laboratoire de Paléontologie, Évolution, Paléoécosystèmes, Paléoprimatologie, Bâtiment B 35 TSA 51106, 6 rue Michel Brunet F- 86073 Poitiers cedex 9 (France)
axelle.gardin@univ-poitiers.fr
Author
Blondel, Cécile
Palevoprim: laboratoire de Paléontologie, Évolution, Paléoécosystèmes, Paléoprimatologie, Bâtiment B 35 TSA 51106, 6 rue Michel Brunet F- 86073 Poitiers cedex 9 (France)
cecile.blondel@univ-poitiers.fr
text
Geodiversitas
2019
2019-09-10
41
15
601
621
journal article
10.5252/geodiversitas2019v41a15
1e89d723-7f54-4d6b-85dd-6bcd573eca32
1638-9395
3694209
urn:lsid:zoobank.org:pub:9DD3CC29-3AEA-44B8-8E8F-6AD882DF5B1C
Pachycynodon amphictina
Teilhard, 1915
n. stat.
Pachycynodon filholi
var.
amphictina
Teilhard, 1915: 38
, pl. IV, fig. 8.
Pachycynodon crassirostris
Schlosser, 1888: 253
. —
Peigné
et al.
2014: 33
, fig. 20a.
REMARK
Teilhard (1915
: pl. IV, fig. 10) figured a mandible from the phosphorites of Quercy (MNHN.F.QU9224) as
Pachycynodon filholi
Schlosser, 1888
var.
amphictina
. It is a small
Pachycynodon
(m1 = 8.8/
4.5 mm
; m2 = 4.3/
4.1 mm
) with p1-p2, p4-m3, the three first premolars being spaced in the mandible. The p1 is single-rooted and asymmetric, the complete mesial half of the crown being projected forward out of the root.
After a short diastema p2 is less asymmetric although the mesial face is almost vertical while the distal face is oblique and, distally, a faint cingulid forms a minute talonid. The p3 is broken off. The p4 is higher than the protoconid of m1 and less asymmetric than p2. A faint cingulid produces a minute mesial basin and a larger one around the distal border. A pacd is situated at midheight of the crown. The low trigonid of m1, with a small height difference between the cuspids, displays a vertical wear facet along the para- and protoconids. The distal face is oblique, with a small notch between metaconid and entocristid and a large one between protoconid and prehypocristid. The m2 is rectangular with a distinct paraconid on the mesio-lingual corner, and a mesially open trigonid basin. The protoconid slightly larger than the metaconid, both with wear facets to the dentine at the tip, but not in contact together, thus leaving an aperture between trigonid and talonid basins. There are wear facets on the mesio-buccal faces of the hypo- and entoconid. The m3 is small and rounded. The two posterior molars, especially m3, are implanted in the ascending ramus of the mandible. We may observe these characters in the mandible with p1-m3 from Valbro (UM VBO 456) figured in
Peigné
et al.
(2014: 32
, 33, fig. 20a), in which the m3 is located higher than the protoconid of m1. There is an original shortening of the mandible by the distal part, re-enforcing the pressure on m1 because there is no pressure in m2 and m3 Thus, m1 is worn down while m3 is still unworn. The two specimens differ from the
type
of
P
.
filholi
, which has less a globular metaconid of m1, more symmetrical p3 and p4, a shorter and more pointed p4 with a pacd located lower, and we consider that they belong to a separate species with the name originally given by Teilhard for a variant.