Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 64. (Budapest 1972)

Jánossy, D.: Middle Pliocene microvertebrate fauna from the Osztramos Loc. 1. (Northern Hungary)

42 D. JÁNOSSY There are three roots in both the upper and the lower molars : a stronger and two weaker ones. Although the third lower molar is wanting, the alveoli of the roots show nearly the same size of M

x and M

2 (no reduction of M

3

!). The broken alveoli in front of the tooth row suggest two roots in P

4

. The length of the lower tooth row may have been 2.3 mm. The measurements of the molars are as follows: length width Rïj dext. in the mandible (1/c) 0.80 0.78 M, dext. 0.86 0.80 Mj (or MJJ) adult (lb) 0.87 0.81 Mj (or M

2

) semiad. (1/c) 0.77 0.77 MJJ (or M,) adult (1/b) 0.84 0.80 JMP/i senile (1/c) 0.78 0.89 M

1

/

2 adult (1/c) 0.65 0.91 Wit adult (1/b) 0.82 0.85 Remarks: In my previous papers (JÁNOSSY 1909, 1970), I summarized briefly our knowledge on the two evolutionary lineages of Eomyidae (the ,,Eomys-]ine" with brachyodont and the ,,Pseudotheridomys-lme" with mesodont-semihypselodont molars). From the locality Osztramos 3, it was now possible to describe a new form, Estramomys simplex JÁNOSSY, 1969, relegable to the second (,,mesodont") lineage (in this year discovered also in locality Osztramos 7). The Eomyid from the locality Osztramos 1, belongs by the above description clearly to the ,,Eomysline". HUGUNEY and MEIN (19(58) recently revised the geologically younger members of this group and showed their close relationship with the North American Pliocene genus Leptodontomys SHOTWELL, 195(5. They relegated to this genus the species „Eomys" catalaunicus HARTENBERGER, 1966, from the Upper Miocene of Con Llobateres and La Grive, and the same species (with the remark aff.) from the Lower Pliocene (Turolien) of Lissieu, France. They gave a new description of the genus and assumed that the tooth described but not illustrated by DEHM (1962) from the Lowest Pleistocene of Schernfeld may be assignable also to it. The remains from Osztramos 1 agree to such an extent with the teeth described as Leptodontomys sp. by SHOTWELL (1967) from the Lower-Middle Pliocene (Claredonian, Hemiphillian) of Oregon that the generic identity is obvious. Only the structure of the anterolophid appears to be different. Besides Leptodontomys, our finds may be compared morphologically with the North American genus Adjidaumo HAY, 1899, but the morphology of the posterolophid of the lower molars is quite different and the geologically older age (the youngest remains Barstovian, from the upper part of the Miocene) makes a relation unlikely. A comparison of our remains with the Eom ys-forms of the European Paleogene shows clear morphological resemblances in the pattern as w

r

ell as in the low crowns of the molars (the Osztramos-form is however more brachyodont!), but they are on the average larger, the mesolophs and mesolophids considerably stronger, and in several details unambiguously different.