Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 11. 1983. (Budapest, 1983)
FRAGMENTA MINERALOGIGA et PALAEONTOLOGICA 11. 1983 p. 41-42 Siren a vus or Eotheroides species (Mammalia, Sirenia) from the Eocene of the Tatabánya Basin (Hungary) By L. KORDOS (Received November 26, 1982) Abstract: A Middle Eocene Sirenia mandible with M -M fragments originated from the Tatabánya Basin (Catalog N V. 60. 685)k This large-size sirenian remain may be near to the Sirenavus and the Eotheroides genera. Identification and locality of the fragmentary mandible of an Eocene Sirenia registered in the Palaeontological Department of the Hungarian Natural History Museum (Budapest) under the inventory number V. 60. 685. are uncertain (Plate I). According to the inventory it was considered as "Sirenavus hungaricus Kretzoi" which came to light from Tata; however, Eocene rocks are unknown from here in the surface. Thus it is highly probable that this bone originated from the limestone quarry at Keselo-HiU in Tatabánya (Felsogalla). At this place already several Middle Eocene Sirenia remains have been found, among others the type specimen of Sirenavus hungaricus Kretzoi (KRETZOI 1941, KORDOS 1981). MORPHOLOGY AND COMPARISON OF THE FIND N°V. 60. 685. Right mandible fragment with M -M . The lower part of the stone-block containing the jaw-bone fragment is actually the'oroRen surface of the mandible, on which roots of teeth may be seen. The upper surface of the block was polished to see the beautiful crosssections of Nummulites in it. As a result the processus coronoideus of the mandible can be seen also in cross-section. The left part of the block contains the original lingual surface of the mandible with the broken M 2 ~Mg teeth and also with the trace of M . Mandible: The length of the find is 15 cm, the estimated length of mandible is approximately 20-22 cm. The breadth of the bulky corpus mandibulae is 3 cm below the Mg, 2. 6 cm below the while 2 cm below the M^. So it is widest below the M^; from here it becomes narrower both forwards and backwards. Between the M^ and the processus coronoideus there is a 1. 8 cm long diastema measured at the altitude of the tooth-crown. According to the section of the bone on the polished surface of the stone, it is probable that the processus coronoideus is wide and slightly bending forward. M^'. length 2.3 cm; width + 1.3 cm. It is closely attached to both M„. The trigonid and talonid of the strongly worn tooth are fused. The abrasion of teeth is the strongest at M 2 , where the masticatory surface becomes already hollow and only the margins of r
