Eomys, Maridet & Hugueney & Heissig, 2010
|
publication ID |
https://doi.org/ 10.5252/g2010n2a3 |
|
persistent identifier |
https://treatment.plazi.org/id/03E18794-0F0F-7240-CCD7-FC7DFD76FBE5 |
|
treatment provided by |
Marcus |
|
scientific name |
Eomys |
| status |
|
Eomys aff. E. zitteli Schlosser, 1884 ( Fig. 5 View FIG R-V)
NEOTYPE. — Right mandible with p4-m3, QT 928, NMB; designated by Fahlbusch (1970: 104).
TYPE LOCALITY. — Quercy (old collections; France).
OTHER STUDIED LOCALITIES. — Saint-Martin-de-Castillon J and E ( France).
TEETH SIZE. — Th e teeth from Saint-Martin-de-Castillon E and J can be first separated from the teeth from Saint- Martin-de-Castillon C and F, based on their larger size. Also a detailed study points out to clear morphological differences.
Neotype of Eomys zitteli (mandible) – p4: 1.10 × 0.97 mm; m1/2: 1.15 × 1.11 mm; 1.13 × 1.15 mm; m3: 1.00 × 0.98 mm.
Measurements for the specimens from Saint-Martin-de- Castillon levels are given in Tables 8; 9 and Figure 7. View FIG
DESCRIPTION
DP4 and P4
Its anteroloph is frequently double, the lingual part being developed, which is rarely the case in other Eomys species ; double anterolophs are also frequent on E. zitteli P4 from Mas-de-Pauffié, DP4 being unknown in this locality.
M1/2
The general morphology is similar to the teeth from the other levels of Saint-Martin-de-Castillon,but some slight differences can be noted with respect to the variation. Th e mesoloph is always well developed as opposed to the teeth from Saint-Martin-de-Castillon F and C where it can be very short or even absent. Some teeth also present a clear division of the mesoloph.Th e shape of the protocone is often elongated and oblique and the teeth are generally proportionally wider than in Saint-Martin-de-Castillon C and F.
Dp4 and p4
The shape of the teeth is more elongated in its anterior part than in Saint-Martin-de-Castillon C and F.
m1/2
No significant differences can be observed on the morphological features, but some differences can be observed on the shape, the teeth being proportionally wider.Th e metalophid is often curved and connected forward on the ectolophid, whereas it is straighter in other levels. In lateral view, no difference can be observed on the height of the crown, but on lingual side the metaconid often presents a bridge merging with median cingulum. This type of morphology is usually absent or weakly marked in Saint-Martinde-Castillon C and F ( Fig. 8 View FIG ). In anterior view the cuspids on labial part of the teeth are generally more developed than on the lingual part.
M3 and m3
Few specimens have been found and no significant differences can be observed either on morphological variability or on tooth shape.
Mandible
A fragmented mandible found in Saint-Martin-de- Castillon E also has a morphology very different from that of Eomys antiquus , with a very deep diastema and a mental foramen located just anterior to p4 ( Fig.4C).It compares more closely with the mandible of the neotype of E. zitteli ( Engesser 1990) .
1.1
1.0
0.9
0.8
0.7
0.6
0.7 0.8 0.9 1.0 1.1 0.7 0.8 0.9 1.0 1.1
1.2 1.2
1.1 1.1
)
mm 1.0 1.0
(
Width 0.9 0.9
0.8 0.8
0.7 0.7
0.7 0.8 0.9 1.0 1.1 1.2 0.7 0.8 0.9 1.0 1.1 1.2
1.0 1.0
0.9 0.9
0.8 0.8
0.7 0.7
0.5 0.6 0.7 0.8 0.9 1.0 1.1 0.5 0.6 0.7 0.8 0.9 1.0 1.1 Length (mm)
between French and Spanish localities The sizes of the teeth from
DISCUSSION
The comparison of the material of Eomys from the four different levels of Saint-Martin-de-Castillon provides some morphological differences in the teeth but also some differences in the shape of the mandible ( Figs 4; 8 View FIG ).
The eomyids from Saint-Martin-de-Castillon E and J are stratigraphically older than those of Saint-Martin-de-Castillon C and F, Saint-Martinde-Castillon E being situated on the same section as Saint-Martin-de-Castillon C, about 10 m below.
The size of the teeth from Saint-Martin-de-Castillon E and J that is larger than most of the teeth from Saint-Martin C and F and some characteristics (less “squared” teeth, mandible) suggest that E. aff. E. antiquus from the younger levels has no relationship with this form. The comparison with the neotype of E. zitteli leads to relate the two populations from Saint-Martin-de-Castillon E and J to E. zitteli . However, because these two localities are older than the localities where E. zitteli was hitherto recognized (Mas-de-Pauffié, Quercy, MP 26) and because the size, though equivalent to that of Mas-de-Pauffié (Comte & Vianey-Liaud 1989) is a little smaller than that of the neotype, we propose E. aff. E. zitteli for Saint-Martin-de-Castillon E and J.
The relationships with the older and larger Eomys sp. from Germany are unclear and the Saint-Martinde-Castillon E and J form is likely an immigrant.
| NMB |
Naturhistorishes Museum |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.