Pliopetaurista pliocaenica (Depéret, 1897)

Colombero, Simone, Pavia, Giulio & Carnevale, Giorgio, 2014, Messinian rodents from Moncucco Torinese, NW Italy: palaeobiodiversity and biochronology, Geodiversitas 36 (3), pp. 421-475 : 457-458

Pliopetaurista pliocaenica (Depéret, 1897) ( Fig. 8C, D )

Sciuropterus pliocaenicus Depéret, 1897: 179 , pl. 18, figs 34, 35.

Pliopetaurista pliocaenica – Mein 1970: 40, figs 66-71. — Adrover et al. 1993b: 98, pl. 6, figs 1-4. — Mörs et al. 1998: 137, figs 3, 1-3. — Dahlmann 2001:54, pl. 9, figs 1-21 (cum syn.). — García-Alix et al. 2007: 273, fig. 4A-E.

TYPE LOCALITY. — Perpignan, France.

OCCURRENCE IN THE STUDIED LAYERS. — MCC5.

REFERRED MATERIAL. — A single isolated M3; a single isolated m1.

MEASUREMENTS. — M3: MGPT-PU 128347 (2.84 × 2.64); m1: MGPT-PU 128218 (2.77 × 2.51).

DESCRIPTION

M3

The anteroloph is well developed and slightly lower than protoloph; protocone located slightly posteriorly with respect to the protoloph-endoloph contact; distal border of endoloph enlarged but not developed into a cusp.

m1

Rugose surface; protoconid and hypoconid connected by ectolophid on which a marked mesoconid is developed; anterolophid well-developed; metalophid interrupted without connection with metaconid; presence of a small hypoconulid on the posterolophid; hypolophid very short.

REMARKS

Large size, sinuous accessory ridges and labyrinthic appearance of the occlusal surface are diagnostic features of the Pteromyinae (García-Alix et al. 2007) . Within this group, the absence of free mesostylids, presence of hypolophids and absence of metaloph in the M3 suggest that the material from MCC can be assigned to the genus Pliopetaurista Kretzoi, 1962 . This genus was present in the Miocene of Europe with the species Pliopetaurista kollmanni Daxner-Höck, 2004 , Pliopetaurista bressana Mein, 1970 , Pliopetaurista dehneli ( Sulimski, 1964) , Pliopetaurista pliocaenica (Depéret, 1897) , and was also present in Asia during the latest part of the Miocene represented by Pliopetaurista rugosa Qiu, 1991 .

P. kollmanni from the Late Miocene of Austria differs from the material from MCC in the considerably smaller teeth, less pronounced loph(id)s (except for the metalophid that is more developed in P. kollmanni ) and tubercles. The Middle to Late Miocene species P. bressana differs from the material of MCC in having a smaller size, less developed ridges and tubercles, a small anterosinusid and slightly more developed metalophids in the lower molars. P. rugosa from the latest Miocene locality of Ertemnte 2 ( Qiu 1991) is larger than specimens from MCC. Moreover, the shape of the M3 is quite different in displaying a reduced basin and a thinner endoloph, not enlarged on the distal side. The size of the material from MCC is close to the higher values of P. dehneli from the type locality of Węże 1 ( Sulimski 1964) and slightly larger than that from the latest Miocene/earliest Pliocene of Greece, Maramena, ( de Bruijn 1995) and Kessani ( Vasileiadou et al. 2012) and from the Early Pliocene of Hautimagne (Mein 1970). The material from MCC mainly differs from P. dehneli in having a less developed metalophid and in the presence of a small hypoconulid. Moreover, the presence of a distal enlargement of the endoloph in the M3 observed in the material from MCC is usually absent in the upper molars of P. dehneli (Mein 1970) .

The size of the specimens from MCC agrees with the lower values of the size range of P. pliocaenica from the Pliocene localities of Wölfersheim (Mein 1970), Arquillo 3 ( Adrover et al. 1993b), and Hambach ( Mörs et al. 1998). The unique M3 assigned to P. pliocaenica from the latest Miocene of Purcal 24A (García-Alix et al. 2007) is larger than the specimen from MCC. Pliopetaurista cf. pliocaenica from the Early Pleistocene locality of Zamkowa Dolna ( Black & Kowalski 1974) is larger than the material from MCC. The morphology of the specimens from MCC remarkably agrees with that of P. pliocaenica , primarily concerning the scarcely developed metalophid, the small hypoconulid in the single m1and the distal enlargement of the endoloph in the M3. Due to this similarity, the material from MCC is assigned to P. pliocaenica .

According to some authors (Mein 1970; Black & Kowalski 1974; de Bruijn 1995) the lineage P. bressana – P. dehneli – P. pliocaenica , characterized by a gradual increase in size, can be recognized within the genus Pliopetaurista . The recent findings of P. pliocaenica in some Upper Turolian localities of Spain (García-Alix et al. 2007), and thus contemporary or even slightly older than P. dehneli from eastern Europe ( de Bruijn 1995; Vasileiadou et al. 2003, 2012), does not seem to support this view. According to García-Alix et al. (2007) the largesized species P. pliocaenica evolved in the Iberian Peninsula and subsequently migrated to central and eastern Europe. The finding from MCC does not disagree with such hypothesis, even though it indicates that the expansion of the geographical range of this species may have occurred before the end of the Miocene, during or suddenly after the MSC.

Figures

FIG. 8. — Isolated teeth of Sciuridae Fischer,1817 from Moncucco Torinese:A, B, Pliopetaurista pliocaenica (Depéret,1897);A, MGPT- PU 128220,M3 dex.; B, MGPT-PU 128221,m1 dex.; C, D, Sciurus warthae Sulimski, 1964; C, MGPT-PU 128347, M3 dex.; D, MGPT- PU 128218, m1 sin. Scale bar: 1 mm.