A new early Late Oligocene (MP 26) continental vertebrate fauna from Saint-Privat-des-Vieux (Alès Basin, Gard, Southern France)
Author
Vianey-Liaud, Monique
Author
Comte, Bernard
Author
Marandat, Bernard
Author
Peigné, Stéphane
Author
Rage, Jean-Claude
Author
Sudre, Jean
text
Geodiversitas
2014
2014-12-26
36
4
565
622
http://dx.doi.org/10.5252/g2014n4a4
journal article
6390
10.5252/g2014n4a4
8bc26961-9853-4113-a63d-4cf691aa7100
1638-9395
4538625
Genus cf.
Geotrypus
Pomel, 1848
(
Fig. 3B
)
TYPE
SPECIES
. —
Geotrypus acutidentatus
de Blainville, 1840
by subsequent designation of de Blainville (1840).
MATERIAL EXAMINED. —
SPV
800-802: one complete lower molar (m1ṙ: L = 2.16, Ltrig. = 1.09, Ltal. = 1.08, wtrig. = 1.35, wtal. = 1.58), and a broken lower molar (m2ṙ), both weakly worn out and one lower premolar.
DESCRIPTION
Ŋe complete molar is probably an m1, the talonid being wider than the trigonid. Ŋe other trigonid being still wider, it would be that of an m2. Cuspids are high.Ŋe hypoconid is as high as the protoconid. Ŋe paraconid is twice as high as the metaconid, and it has the same height as the entoconid. Seen in lingual profile, the metaconid is almost cylindrical, sharper only at the top. Ŋe lingual profile of the entoconid is more conical than the metaconid, but with a relatively narrow base and an acute angle at the top. Ŋe postcristid is directly and transversely connected with the entoconid. Ŋere is no preentocristid. A strong entostylid can be seen near the end of the very low posterior cingulum. It then extends to the lingual surface of the tooth more or less continuously, by a weak cingular bulge dotted with more or less distant vertical crestules, to join the anterior cingulid. At the lingual base of the crown the collar is rectilinear.
FIG. 2 — Serpentes from Saint-Privat-des-Vieux (Gard; Lower Chattian, MP 26),
Platyspondylia
sp.:
A -C
, anterior caudal vertebra (SPV738):
A
, anterior view;
B
, left lateral view;
C
, ventral view;
D -F
: caudal vertebra (SPV739) from the anterior caudal region, but posterior to SPV738:
D
, anterior view;
E
, left lateral view;
F
, ventral view;
G -I
: mid-caudal vertebra (SPV740);
G
, in anterior view;
H
, left lateral view;
I
, ventral view. Scale bars: 2 mm.
Ŋe anterior cingulid extends labially and disappears at the base of the protoconid. Labially a weak and very low cingulum limits the base of the hypoflexid; it does not extend to the base of the hypoconid.
DISCUSSION
Ŋese specimens show similarities with
Geotrypus
(cusps very slender, somewhat lingually oblique ridge joining the base of the posterior trigonid wall, entocristid reduced or absent, anterior cingulum developed;
Crochet 1995
). However, a number of differences prevent its attribution with certainty to that genus. Ŋe lingual cusps are more slender than those of
Geotrypus
cf.
acutidentatus
(de Blainville, 1840)
from Le Garouillas (Lot, Quercy, MP 25). Ŋe teeth from Saint-Privat-des-Vieux differ from those of this species and also from
Geotrypus antiquus
(de Blainville, 1840)
from Pech du Fraysse (MP 28) by their larger size and especially their width. Ŋey also differ from these two species in having longer cingulid, smaller parastylid and stronger entostylid, a small difference in height between protoconid and hypoconid and the development of a very low and discontinuous labial cingulid. Ŋe lingual base of the crown is in the same vertical plane while it is concave at the opening of the trigonid in
G. antiquus
. It shares with these two species the well cuspidate paraconid, the high labial elongation of the anterior cingulid, and with
G.
cf.
acutidentatus
the absence of entocristid. It differs from the
type
of
Myxomygale
(Filhol, 1890)
by the absence of entocristid and metastylid, and the
crista obliqua
ending less lingually.