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
Lophiomeryx
cf.
chalaniati
Pomel, 1854
MATERIAL EXAMINED
AND
MEASUREMENTS (in mm). — One left P4: 10.4 × 10.7; one left p3, 12.6 × 5; talus, L
=
61.
DESCRIPTION AND COMPARISONS
Ŋe P4, almost as long as wide, is remarked by its incipient molarization.Indeed, on the flat but slightly
concave ectoloph, the outer cusp begins to divide. Ŋe postprotocrista shows a particularly clear median bifurcation.Ŋe anterior cingulum is short and strong. Ŋe posterior cingulum, very strong also, stands up to the mid of the posprotocrista. Size and morphology of this specimen are the closest to those of the P4 of
Lophiomeryx
cf.
chalaniati
from Le Garouillas (
Sudre 1995
).Among the rich material from this locality,some P4 show an early bifurcation of the postprotocrista, and a beginning of division of the outer cusp. However, none has a degree of molarization as advanced as that observed on the tooth of Saint-Privat-des-Vieux. Ŋis morphology is unknown in other selenodont artiodactyls from the mid-Oligocene confirming the more derived state of this form.Ŋe p3,very elongated and provided with a longitudinal ridge, has morphol - ogy consistent with that of
L.
cf.
chalaniati
from Le Garouillas (
Sudre 1995
: fig. 14a, b).
A calcaneus is also reported to this form (
Fig. 16
). Ŋe body is massive with a wide
caput calcanei
and the
sustentaculum tali
projecting medially and very thick rearwardly; the tendinous slide is flat medio-laterally and rounded dorsoventrally. Ŋe morphology of the surface suggests the important role of the
tensio flexor
of the phalanges. Ŋis is a configuration similar to that observed in the calcaneus of
Lophiomeryx
from Le Garouillas (
Sudre 1995: 231
, fig. 16), the latter being slightly smaller (L mean
=
58.6 mm
); the size of the specimen from Saint-Privat-des-Vieux exceeds the maximum value recorded in the form of Le Garouillas. On the basis of the material of
L. chalaniati
from Le Garouillas, the distal ends of the appendicular skeleton of this species show short and robust metapodials, and metatarsals nearly as long as the metacarpals (
Sudre 1995
). Ŋese features characterize a walking animal, and the species is probably dependent on soft soils, close to aquatic environments (
Trofimov 1957
;
Blondel 1998
). Ŋe paleoecological study of the fauna from Le Garouillas suggests such an environmental context (
Legendre 1995
).
With regard to the largest mammals known from Saint-Privat-des-Vieux, we can estimate the weight of the animal as about
25 kg
if one refers to that established for
L.
cf.
chalaniati
from Le Garouillas (
Legendre 1995
;
Martinez & Sudre 1997
).
Ŋe chronological extension of the lineage of
Lophiomeryx
, initiated at the beginning of the Oligocene (
L. mouchelini
, at Villebramar, MP 21;
Brunet& Sudre 1987
) lasts up to the level MP 28. Ŋe last representative of the lineage is known from the site of Pech-Desse (MP 28a;
Blondel 1996
). Ŋe dental elements referred to the species
chalaniati
from localities more recent than Le Garouillas does not allow meaningful comparisons.