Microtocricetus molassicus Mayr & Fahlbusch, 1975

Hír, János & Kókay, József, 2010, A systematic study of the middle-late Miocene rodents and lagomorphs (Mammalia) of Felsőtárkány 3 / 8 and 3 / 10 (Northern Hungary) with stratigraphical relations, Geodiversitas 32 (2), pp. 307-329 : 322

Microtocricetus molassicus Mayr & Fahlbusch, 1975

MATERIAL EXAMINED. — See Table 16 for data and measurements.

DESCRIPTION

The molars are semihypsodont. Th e unique M1 represents a subadult specimen. The flat occlusal surface consists of three lingual and four labial anticlines. It has a weak anteromesoloph.Th e molars from FT 3/8 (2007.218, 2007.219, 2007.226) probably belong to one individual, because the occlusal surfaces are not yet flattened due to the early ontogenetic stage of the specimen. Th e M3 has three lingual and four labial anticlines.Th ere are two islets in the anteroloph. The paracone is independent.Th e mesoloph and the metacone are labially connected. Th e posterior lobe is narrow and rounded. Th e occlusal surface of m1 is formed by five lingual and four labial anticlines. The anteroconid encloses a large islet. The occlusal complex formed by the anteroconid, protoconid and metaconid is very similar to an anteroconid complex of an arvicolid m1.Th e m2 is made up by four lingual and four labial anticlines forming four transversal lobes. Th ere is a small islet in the anterolophid.The longitudinal connection between the lobes is incipient. The posterior lobe is narrower than the three others.

COMMENTS

The morphology of the molars concurs in all with the detailed descriptions of Mayr & Fahlbusch (1975), Kowalski (1993), Fejfar (1999), Kretzoi & Fejfar (2005). In these publications Microtocricetus is regarded as a typical but relatively rare element of MN 9 faunas. Th e European occurences are listed by Kretzoi & Fejfar (2005). Th is list is not reinterpreted here, only three new localities are added: Borsky Sväty Jur and Pezinok in Slovakia ( Sabol et al. 2004), Nebelbergweg-Transitgasleitung II in Switzerland ( Engesser & Kälin 2005).

The coexistence of Collimys and Microtocricetus association was only known in two localities in Europe: Hammerschmiede with Megacricetodon minutus- Collimys sp.- Microtocricetus molassicus association. Originally the Collimys remains from this locality have been partially described as “ Democricetodon gaillardi (Schaub, 1925) - D. freisingensis Fahlbusch, 1964 ” by Mayr & Fahlbusch (1975) and later corrected to Collimys by Kälin (1999) (recently this material was described as Collimys hiri [ Prieto 2008; Prieto &Rummel 2009]). Th e other locality is Belchatow A with Eumyarion-Democricetodon sp. (1-2) - Megacricetodon aff. minor (Lartet, 1851) - Collimys transversus Heissig, 1995 - Microtocricetus molassicus hamster association. However, Collimys is a rare element in Belchatow A, its frequency is 0.2% ( Garapich 2002).

In the Vienna Basin, the occurence of Microtocricetus is reported from the locality Richardhof-Golfplatz. This locality is dated as Early Pannonian, and referred to the mollusc zone E ( Congeria subglobosa Partsch, 1835 ) = C5n2n paleomagnetic zone =10.1-10.2 Myr by Daxner-Höck (2004a, b). Th e slightly older age of the Microtocricetus findings from Felsőtárkány 3/8 and 3/10 is possible because the mollusc material of the Felsőtárkány localities is undoubtedly Sarmatian and Collimys is absent in the MN 9 faunas of the Vienna Basin. Microtocricetus molassicus is the best potential rodent candidate for the “index fossil” status of the MN 9 zone in Central Europe ( De Bruijn et al. 1992) but the exact datation of the FAD of this species is not known.

Family ANOMALOMYIDAE De Bruijn, 1984