Praearmantomys crusafonti de Bruijn, 1966

Ruiz-Sánchez, Francisco J., Murelaga, Xabier, Larrasoaña, Juan C., Freudenthal, Matthijs & Garcés, Miguel, 2012, Hypsodont Myomiminae (Gliridae, Rodentia) from five new localities in the Lower Miocene Tudela Formation (Bardenas Reales, Ebro Basin, Spain) and their bearing on the age of the Agenian-Ramblian boundary, Geodiversitas 34 (3), pp. 645-663 : 657

cf. Praearmantomys crusafonti de Bruijn, 1966 ( Fig. 4S )

HOLOTYPE. — Ateca 1, fragment mandible and maxila with incomplete dentition (Nr. 72, 73, 74 and 75; de Bruijn 1966: pl. I; figs 1-4).

TYPE LOCALITY. — Ateca 1, Ebro Basin, Spain.

LOCALITY AND AGE. — Cabezo Carboneras 1 ( CC 1), Province of Navarre, Spain. Agenian (Local subzone Y2, MN 2).

MATERIAL AND MEASUREMENTS (L × W). — CC 1-22 (13.92 × 14.31), right m3.

DESCRIPTION

m3

Posterolingual side very reduced with a subtriangular shape.Anterolophid separated from the protoconid by a deep furrow. Metalophid connected to metaconid. Centrolophid absent.Mesolophid transverse and connected to the labial end of the posterolophid. Mesolophid and posterolophid separated at the entoconid.

In CC1 a m3 of large size has been recovered. Its size and above all its hypsodonty are very similar to Praearmantomys . The ridges are vertical. The size is larger than A. bijmai and A. daamsi and similar to the populations of A. parsani . The hypsodonty is very different from these latter species.

The shape of this molar is characterized by the strong reduction of posterolingual side. This morphology has been cited in populations of P. crusafonti ( Daams 1990) and seems to be characteristic of this genus.

For the mesolophid of m3 of P. crusafonti from Cabeza Rubia two morphotypes have been figured ( Daams 1990). The first (2 out of 3 specimens), with a transverse mesolophid not connected to the posterolophid and the second with a mesolophid connected to the posterolophid forming a Y-shape. In the rest of the populations of P. crusafonti the first morphotype is very poorly represented.In the m3 from CC1 the mesolophid is transverse and connected to the posterolophid on the labial side of the tooth.The mesolophid from CC1 is similar but not identical to the first morphotype described by Daams, because the mesolophid is connected on the labial border.

The fossil record of P.crusafonti ranges from uppermost Agenian to Lower Aragonian ( Fig.3 ). In Cabeza Rubia (Upper Agenian,zone Y2) P.crusafonti has been cited together with A. parsani ( Daams 1990) .Cabezo Carboneras 1 (CC1) contains an unknown glirid association of P.crusafonti with A. daamsi . This implies an older age for CC1 and may explain the presence of a morphotype that is not known in Cabeza Rubia. The material is too poor to draw solid conclusions.

Figures

FIG. 4. — A-E, Armantomys cf. bijmai from Cabezo Hermoso 1 (CH1): A, left M2,CH1-6;B, right M3,CH1-8; C, right P4,CH1-4;D, right D4, CH1-5; E, right m1, CH1-3; F-M, Armantomys daamsi from Cuesta Agujeros 2 (CA2): F, left M1, CA2/1-6; G, right M2, CA2/1-5; H, right M2, CA2/2-6; I, right M3, CA2/1-15; J, right P4, CA2/1-12; K, left m1, CA2/1-8; L, left m1, CA2/1-10; M, right m3, CA2/2-5; N, Armantomys cf. jasperi from Cuesta Agujeros 4 (CA4), fragmentary right m2, CA4/1-27; O, P, Armantomys cf. parsani from Cuesta Agujeros 3 (CA3): O, left M2, CA3-1; P, left P4, CA3-2; Q, R, Armantomys cf. daamsi from Cabezo Carboneras 1 (CC1): Q, right M1, CC1-31; R, left M2, CC1-38; S, cf. Praearmantomys crusafonti from Cabezo Carboneras 1 (CC1), right m3, CC1-22. Scale bar:1 mm.

FIG. 3. — Distribution chart of the Myomiminae species studied in this paper and in Daams (1990). The succession of the localities from Daams (1990) is, though in stratigraphical order, not calibrated.