Eliomys aff. intermedius Friant, 1953

Colombero, Simone, Pavia, Giulio & Carnevale, Giorgio, 2014, Messinian rodents from Moncucco Torinese, NW Italy: palaeobiodiversity and biochronology, Geodiversitas 36 (3), pp. 421-475 : 446-447

Eliomys aff. intermedius Friant, 1953 ( Fig. 6 A-E)

Eliomys cf. truci – Angelone et al. 2011: 99, fig. 6 (17).

TYPE LOCALITY. — Sète, France.

OCCURRENCE IN THE STUDIED LAYERS. — MCC4; MCC5; MCC7.

REFERRED MATERIAL. — A single P4, three M1, two M2, two m1, and a single m2.

MEASUREMENTS. — Table 8.

DESCRIPTION

P4

Triangular outline; anteroloph short and connected to the paracone; the anterior centroloph extends to the midpoint of the tooth; posteroloph not fused with metacone.

M1-2

M1 and M2 display a very similar dental pattern; the M2 usually presents a less concave anteroloph; molars are shallow basined with trapezoidal outline, the lingual side being slightly shorter than the labial one; endoloph strong and continuous; paracone slightly stouter and higher than the metacone; the anterior centroloph reaches the midpoint of the molar; posterior centroloph always present; in both M2 and in one of three M1 the posterior centroloph fuses with the anterior centroloph forming a “Y-shaped” ridge that extends to the midpoint of the molar.

m1

Trapezoid in outline; the endolophid is discontinuous; anterolophid connected to protoconid in one of the two available specimens; metalophid connected to metaconid; centrolophid extending beyond the midpoint of the molar; well-developed posterior extra ridge; in both specimens, the connection between hypoconid and posterolophid marked by a slight narrowing of the ridge.

m2

Broader than long; the endolophid is discontinous; anterolophid not connected to the protoconid; metalophid not connected with the metaconid; centrolophid short; very reduced posterior extra ridge.

REMARKS

The presence of a continuous and strong endoloph in the upper molars excludes any possible assignment of the material from MCC to the genus Myomimus Ognev, 1924 . The presence of wider than long lower molars and continuous, strong endolophs in upper molars are characteristic of the genera Dryomys Thomas, 1906 and Eliomys Wagner, 1840 . According to Freudenthal & Martín-Suárez (2006), the presence of an endolophid in the lower molars might be used to separate Dryomys from Eliomys . For this reason, we assign the specimens from MCC to the genus Eliomys .

Direct comparisons with Eliomys truci Mein & Michaux, 1970 , a species distributed in Europe between the Late Miocene and the Late Pliocene, from the Early Ruscinian locality of Hautimagne, evidenced that the specimens from MCC mainly differ in the presence of a posterior centroloph in the upper molars, a shorter centrolophid in the m2 and in the strong reduction of the secondary accessory ridge in the m2. Moreover, in the m1-2 of E. truci from the Granada and Guadix basin, the metalophid-meta- conid connection and the anterolophid-protoconid connection are rarer compared to the material from MCC (García-Alix et al. 2008a). The measurements of the teeth from MCC are slightly larger than those of E. truci from Hautimagne ( Mein & Michaux 1970), Los Mansuetos, Concud 2 and 3 ( van de Weerd 1976), Tollo de Chiclana 13 and 1B, Purcal 23 and 25a, La Dehesa 1 and 16, and Otura 1 and 4 (García-Alix et al. 2008a), especially as regards the width, whereas the length of the specimens of some other assemblages such as Masada del Valle 2 and 5, Concud Barranco de las Calaveras ( van de Weerd 1976), and La Gloria 4 ( Adrover et al. 1993a) is very close to that of MCC.

The measurements of Eliomys intermedius Friant, 1953 , widespread in Europe between the Late Miocene and the Pleistocene, are usually larger than those of the sample from MCC ( van de Weerd 1976; García-Alix et al. 2008a). Recent observations on some teeth from the type locality of Sète revealed that the remains of Eliomys from MCC share some morphological characteristics with this species, such as the presence of a posterior centroloph in the upper molars and the rounded outline of some dental elements, particularly the m2. Moreover, E. intermedius displays metalophid-metaconid and anterolophid-protoconid connections as observed in the small sample of MCC. The morphology of the lower molars from MCC is also similar to that of E. intermedius since the single m2 exhibits a strong reduction of the secondary posterior ridge even if in the latter species the reduction is stronger and frequently reported in the lower molars (García-Alix et al. 2008a). In a previous paper, Angelone et al. (2011) assigned a single left M1 from MCC (MGPT-PU 127) (erroneously identified as an M3) to Eliomys cf. truci ; this molar is referred herein to as Eliomys aff. intermedius because its morphological features fit well with E. intermedius ,even if the size is smaller and closer to that of E. truci . Some assemblages of Eliomys from Greek and Spanish localities of Late Miocene/Early Pliocene age are referred to Eliomys aff. intermedius ( de Bruijn et al. 1970; Adrover et al. 1993a; García-Alix et al. 2008a),because they share an intermediate size between E.truci and E.intermedius and display morphological traits that fit better with E. intermedius , such as the presence of a posterior centroloph, more developed metalophid-metaconid and anterolophid-protoconid connections, and reduction of the posterior extra ridge. The assemblage of MCC exhibits some peculiar morphological features, such as the common occurrence of fused centrolophs developing into a Y-shaped ridge and a strong reduction of the posterior extra ridge in the m2. These assemblages are referred to E. aff. intermedius because the material is not rich enough to determine a clear attribution. Moreover even if the studied specimens display similar morphological features to those of E. intermedius , some reliable differences with the type locality assemblage, prevent us to securely refer the material from MCC to this species.

Figures

FIG. 6. — Isolated teeth of Eliomys Wagner, 1840 and Muscardinus Kaup, 1829 from Moncucco Torinese:A-E, Eliomys aff.intermedius Friant, 1953; A, MGPT-PU12128348, P4 dex.; B, MGPT-PU128270 M1 sin.; C, MGPT-PU127495, M2 sin.; D, MGPT-PU128269, m1 dex.; E, MGPT-PU127127368, m2 dex.; F-P, Muscardinus vireti Hugueney & Mein, 1965; F, MGPT-PU127604, P4 dex.; G, MGPT- PU12392, M1 dex.; H, MGPT-PU127606, M2 sin.; I, MGPT-PU128178, M2 dex.; J, MGPT-PU127607, M3 dex.; K, MGPT-PU128182, M3 dex.; L, MGPT-PU127608, p4 sin.; M, MGPT-PU127609, m1 dex.; N, MGPT-PU127610, m2 sin.; O, MGPT-PU127611, m3 sin.; P, MGPT-PU127513, m3 dex. Scale bar: 1 mm.