Cricetus nanus (Schaub, 1930)
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publication ID |
https://doi.org/10.17111/FragmPalHung.2016.33.99 |
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DOI |
https://doi.org/10.5281/zenodo.15681957 |
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persistent identifier |
https://treatment.plazi.org/id/F152ED01-DF17-3911-FDA5-8360B7444736 |
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treatment provided by |
Felipe |
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scientific name |
Cricetus nanus (Schaub, 1930) |
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( Figs 25–30 View Figs 25–30 )
Material – 8 maxillae with complete tooth rows, 21 maxillae with incomplete tooth rows, 10 mandibulae with complete tooth rows, 13 mandibulae with incomplete tooth rows, 24 M 1, 24 M 2, 23 M 3, 18 M
1, 10 M
2, 12 M
3.
Measurements – Tables 6 View Table 6 and 7 View Table 7 .
Description – M 1: The mesial surface is smooth, anterostyle is rare: 7/45. The relatively wide anterocone consists of two equally developed cones, which are as well-developed as the other main cones of M 1: proto-, para-, hypo- and metacones. Parastyle is not developed as cuspula, only low developed cingulum is found. Protolophule 1 is nearly constant: 41/45. Short remnant mesoloph is found only in 1/45, which is developed on the anterior surface of the metacone. There are four roots and one tiny root under the paracone.
M 2: It shows rectangular outline. The labial anteroloph is slightly stronger than the lingual one. Protolophule 1 is constant. Short remnant mesoloph is rare: 7/44, which is developed on the anterior surface of the metacone. It has four roots.
M 3: It shows subtriangular outline, the hypocone and the metacone are reduced. Some morphological elements defined by HÍR (1998, fig. 28) are rare: central ring: 4/44, remnant mesoloph: 8/44. There are three roots.
M 1: It has elongated trapezoidal outline. The anteroconid region is narrower than the width across the hypoconid and the entoconid. The anteroconid consists of two equally developed cuspulas. Those are smaller than the other main cusps (proto-, meta-, hypo- and entoconid) of the M 1. The anterolophulid connects the labial cuspula of the anteroconid and the protoconid. Y-like anterolophulid (which has two, equally developed anterior branches running to the two cuspulas of the anteroconid) was found only in one case. Additional morphological elements (anterostylid, mesolophid, mesoconid, lingual anterolophulid) are completely missing. It has two roots.
M 2: It has rectangular outline. Lingual anterocingulum is missing: 10/30, short: 10/30, middle developed: 8/30, or long: 2/30. Short mesolophid is rare (2/30), which reaches the posterior basis of the metaconid. There is no mesoconid, but central ring is developed in one case. It has two roots.
M 3: It shows subtriangular outline, the entoconid is reduced. Lingual antrocingulum is missing: 7/31, short: 7/31, middle developed: 13/31, or long: 4/31. Mesolophid is missing: 8/31, it is short, does not reach the posterior basis of the metaconid: 2/31. It reaches the posterior basis of the metaconid: 21/31. A central ring is missing: 11/31, or developed: 20/31. Two roots.
Remarks – Originally this hamster was described as a subspecies, Cricetus cricetus nanus (Schaub, 1930) . But on the basis of the metrical and morphological characters and also their stratigraphical range Hír regarded this taxon as a distinct species: Cricetus nanus ( HÍR 1994, 1997).
Related to the other C. nanus populations studied by HÍR (1994) the material of Beremend 14 is special because of the relatively small dimensions and the more frequent mesolophids and central rings in the morphology of M 3. These characters suggest that the larger hamster from Beremend 14 can be an early representative of C. nanus ( Figs 31 View Fig –32).
The flourishing of the species is experienced in the typical Allophaiomys faunas without progressive Microtus and Pitymys species ( Poland: Zabia; Bohemia: Chlum 6; Slovakia: Kolinany 3, Vcelare 3b/1, Vcelare 4a/5, Vcelare 4a/7, Vcelare 4e, Vcelare 5, Vcelare 6; Hungary: Osztramos 2, Osztamos 8, Osztramos 14; Romania: Betfia 2, Betfia 10; Russia: Akkulaevo 2, Akkulaevo 3) ( HÍR 1994). Later the presence of C. nanus with reduced abundance was verified in the fauna of the Somssich Hill 2 ( HÍR 1998). The last occurrence of C. nanus was found in the 12th level of the Tarkő Rock-shelter ( HÍR 1994).
Up to the present we had no data on the ancestors and the origin of this hamster.
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