Eomys sp.
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publication ID |
https://doi.org/ 10.5252/g2010n2a3 |
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persistent identifier |
https://treatment.plazi.org/id/03E18794-0F09-7242-CD6F-FB03FE2CFA28 |
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treatment provided by |
Marcus |
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scientific name |
Eomys sp. |
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Eomys sp. ( Fig. 9 View FIG A-D)
LOCALITIES. — Möhren 20 and 19 ( Germany).Möhren 13 (the two teeth are broken and cannot be measured).
TEETH SIZE. — In German localities a first smaller species of eomyid has been previously described in this study as E. antiquus , but two larger species were also found. We first study the smallest of these two ones.
Möhren 19 – M3: 1.105 × 1.210 mm.
Measurements for the locality Möhren 20 are given in Table 10.
DESCRIPTION
P4
The tooth is square-shaped, with relatively massive cusps. Th e paracone is disconnected from the protocone. Th ere is no lingual anteroloph, and
A
B
the labial one is weakly developed. The mesoloph is short or absent.
M1/2
The teeth have no lingual anteroloph. The labial anteroloph is always long, starting on a protoconule separated from the base of the protoloph. The mesoloph is short, one tooth has a second mesoloph that is oblique and forward-oriented ( Fig. 9B View FIG ).
M3
The metaloph is in all cases well developed, but opposite to E. antiquus , an accessory crest appears between the basis of the protoloph and the metaloph. The general shape of the teeth is triangular with the posterior part longer than in E. antiquus .
m1/2
Despite the larger size, the teeth morphology is similar to E. antiquus . Th e labial and lingual anterolophids are generally both well developed, but the labial one can sometimes be shorter.
When the labial anterolophid is strongly developed, the sinus between it and the protoconid can be very wide, leading to a round shape of the anterolophid that is clearly observable in the tooth outline.
The anterolophids are usually connected to the protoconid, but the connection can sometimes be more lingual and connected to the metalophulid, and sometimes disconnected leading to an isolated forward crest. The mesolophid has little variability, generally of average size.
m3
The tooth is broken on its forepart. The mesolophid is of medium length and has a posteriorly oriented spur, but does not reach the posterolophid. On the lingual part, the entoconid is reduced to a bump on the posterolophid, but is clearly visible.
DISCUSSION
These populations can be differentiated from Eomys antiquus from the same localities based mainly on their larger size ( Fig. 3; Table 10). The previous description was primarily based on the population found in Möhren 20 where 15 teeth have been found, whereas only two teeth have been found in Möhren 13 and just one in Möhren 19. The morphology of this form is similar to E. antiquus except for the more massive cusps.
The measurements of this population seem to fit with the size of E. molassicus , but one of the diagnostic features of E. molassicus is the presence of long mesolophids whereas they are short on these populations from Möhren 20, 13 and 19. Eomys ebnatensis Engesser, 1987 is also different because of its long mesolophids, larger size and quite mesodont morphology. For these reasons this new material from Bavaria appears to be an original species. It should also be compared with the large teeth from Hoogbutsel described as E. cf. antiquus ( Fahlbusch 1973) .
The morphology of Eomys sp. , with massive cusps and short mesolophids is reminiscent of that of E. major Freudenberg, 1941 from the late Oligocene of Gaimersheim (the type locality) and also Eomys sp. of Treuchtlingen. As the populations of Gaimersheim and Treuchtlingen are larger in size, this population from the Earlier Oligocene could be considered as related to E. major with Eomys sp. from Treuchtlingen as an intermediate form. However the gap in the fossil record between the Early and late Oligocene in Bavaria does not allow to further test this assumption. We therefore propose to leave the nomenclature open, Eomys sp.
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