Simplomys, García-Paredes & Peláez-Campomanes & Álvarez-Sierra, 2009

García-Paredes, Israel, Peláez-Campomanes, Pablo & Álvarez-Sierra, M. Ángeles, 2009, Gliridae (Rodentia, Mammalia) with a simple dental pattern: a new genus and new species from the European Early and Middle Miocene, Zoological Journal of the Linnean Society 157 (3), pp. 622-652 : 640-641

REMARKS ON SIMPLOMYS ROBUSTUS

Simplomys robustus is rare in the fossil record. Its stratigraphical distribution is restricted to the Ramblian and lowest Aragonian (Lower Miocene). In Spain it is present in the Calatayud–Montalbán basin and in the Vallès–Penedès basin ( Agustí, 1981). Ginsburg, Morales & Soria (1987) cited Ps. robustus from the locality Valquemado (Tagus basin, local zone Y1). However, in later papers ( Álvarez Sierra, Daams & Peláez-Campomanes, 1994; Morales et al., 1999) this material is referred to as Pseudodryomys [= Simplomys ?] sp. Simplomys robustus is also present in Portugal ( Antunes, 1984) and France (e.g. Aguilar et al., 1999) (see Supporting Information Appendix S1 for details on localities and references).

SIMPLOMYS ALJAPHI (HUGUENEY ET AL., 1978)

( FIG. 6 )

Original diagnosis ( Hugueney et al., 1978: 28, translated from French): ‘[ Pseudodryomys similar in size to P. ibericus and P. simplicidens , close to P. ibericus by the evolutionary degree of its M1-2, which also possesses centrolophs and sometimes accessory ridges, but with a protoloph almost parallel to the metaloph, which gives a quite less pointed trigon on the upper molars; this new species on the whole has more simple molars than P. ibericus , with P4 and M3 much more reduced and very simplified. The reduction of the P4 and M3 is not as extreme as in P. simplicidens , which, in addition, has upper molars without centrolophs]’.

Emended diagnosis: Medium-sized Simplomys . The dental pattern of the upper molars is formed by the four main ridges. Centrolophs may be present. Sometimes tiny extra ridges are present inside the trigon. The M1 and M2 show a protoloph almost parallel to the metaloph; both ridges are joined near the lingual border. The dental pattern of m1 and m2 consists of the four main ridges and a well-developed centrolophid. The centrolophid does not exceed the central axis of the occlusal surface. The m1 and m2 also may possess tiny and low extra ridges in variable positions. The premolars and the m3 show the lowest degree of reduction and simplification amongst species of Simplomys gen. nov.

Differential diagnosis: Simplomys aljaphi differs from S. simplicidens by its less reduced and simplified premolars and m3. When centrolophs are present in the M1 and M2, they extend diagonally into the central valley. The anterior one is always present and longer than the posterior one in S. aljaphi , whereas in S. simplicidens the centrolophs are closer to being parallel to protoloph and/or metaloph and the posterior one is longer. Simplomys aljaphi differs from S. simplicidens by having, in general, a more complicated dental pattern in the lower molars that may include tiny and low extra ridges.

Simplomys aljaphi differs from S. robustus by its smaller size and its more complicated dental pattern.

Type locality: Montaigu-le-Blin , Allier , Central Massif basin, France ( MN 2 , Lower Miocene) .

Stratigraphical distribution: Local zones X to Y (MN 1-MN 2, Lower Miocene).

Geographical distribution: Spain, France, and Switzerland.

Figures

Figure 6. Simplomys aljaphi (Hugueney et al., 1978) from Montaigu-le-Blin (modified after Hugueney et al., 1978). A, P4-M3 AC. MB 191 holotype. B, p4-m3 P.O. C, P4 AC. MB 103. D, M1 F.S.L. 97 461. E, m3 AC. MB 706. F, m3 F.S.L. 97 464. Right side specimens underlined. Holotype in italics.