Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 20. 2002. (Budapest, 2002)

Eocene Sirenia Sirenavus is a small-sized Sirenia regarded as primitive, because its premaxillae contact the frontals; the large nasals meet in the midline; the mandibular symphysis is elongated and laterally compressed On the other hand, it was highly adapted to the aquatic environment, as concluded from the extremely inflated symphyseal part of its mandibles; from the strongly concave ventral border of the horizontal mandibular ramus; from its very compact bones as well as from the relatively small from Hungary 45 hind limbs that were in function. The overall morphology of Sirenavus has a great resemblance to Eotheroides aegyptiacum OWEN 1875 fin ABEL 1912, Taf. I. 2., Taf. IL 1-2., Ind Hl). In agreement with this, the cladistic analysis of DOMNING (1994) placed Sirenavus close to Eotheroides aegyptiacum. From the systematic point of view Sirenavus is an incertae sedis of Dugongidae (DOMNING 1996), or belongs to the subfamily HaHtheriinae. Anisosiren pannonica KORDOS, 1979 From the Middle Eocene of Oroszlány, KORDOS (1979) described the new fossil sea cow Anisosiren pannonica on the basis of a left maxilla with P

3

, F-M

3 (MAFI V.11748, Vt.77). Revised characters of the srxximen are the following ones: Maxilla — The zygomatic-orbital bridge of the maxilla is nearly in the same level as the palate; the anterior margin of the orbit is located in the level of M

2

. Upper dentition — The tooth-row is strongly convex; the greatest breadth of the palate (in reconstruction) is reached at the level of M

2

; the largest molar is M

3

. M

2 — The M

2 has a biloph stmcture and is bucco-lingually wide; the anterior cingula with cusp are weU-developed; the lingual cingula are strong; the most buccal paracon and the mesio-distally oriented protocone build a protoloph; the metaloph has a rhomboid form, including a larger hypocone and a smaller metacone; between the proto- and metaloph there is a deep transverse valley. M

3 — The length and the breadth of the tooth is almost equal; the anterior cingula are well-developed, form a crista; the lingual cingula are very strong, close around a large depression; the metalophe is divided in three cusps (with a large undvided hypo-metaconus at the midline and one smaller cusp on both the lingual and buccal sides). No sigriificant differences in the morphological characters of the upper dentition indicate the allocation of Anisosiren to another genus or the recognition of the type specimen as an independent genus and species. Following the classification of DOMMNG (1996), Anisosiren is a Dugongidae incertae sedis. Sirenia indet. I (earlier: Protosiren) A mandble fragment of a small-sized animal with M2 (MÁFI V. 11423) from the Middle Eocene of the Felsőgalla locality (Tatabánya Basin) was referred to Protosiren d. fraasi ABEL (KORDOS 1978) because its size and morphology was very similar to that of the small subadult dentary described and illustrated by PRIEM (1908) as P. fraasi. DOMNLNG et al. (1982) identified some specimens, mcluding a small mandble (USNM 214596), as Protosiren species from the Eocene of North Carolina. GlNGERICH et al. (1994) re-investigated the type skull of Protosiren fraasi ABEL (CGM 10171) and concluded that Protosiren fraasi is a valid genus and species distinct from Eotheroides aegyptiacum (OWEN). Protosiren has a large dentary with large molars and wide mandbular rostrum, whereas Eotheroides has a smaller dentale with smaller molars and a narrower rostrum than the Egyptian specimen (PRIEM 1908). DOMNING & GlNGERICH (1994) described a new species, Protosiren smithae as a probable direct descendant of P. fraasi. These authors concluded that the narrow-jawed sirenian from the Eocene of North Carolina referred to Protosiren sp. by DOMNING et al. (1982) does not belong to that genus. The third species of this genus is Protosiren sattaensis from the Pakistan Middle Eocene (GlNGERICH et al. 1995). In conclusion, on the level of our present knowledge, the small-sized specimens from the Middle Eocene of Egypt (PRIEM 1908), from Hungary (KORDOS 1978), from North Carolina and Florida (DOMNING et al. 1982; DOMNING 2001) formerly known as Protosiren do not belong in that genus. These specimens await systematic description. In contrast with the mandble illustrated by PRIEM (1908), the MAH V. 11423 specimen has the following characters of M2: well devdoped mesio-buccal angular cusp ("Vorderers Basalband'*); entoconid in lateral view more asymmetric; welldeveloped cristid obliqua that is longer and has a connection buccally with the protolophid; hypoconulid lophule has three pointed cusps, the buccal one is connected with the mesolophid For the M2 of the USNM 214596 specimen characteristics are in lateral view the meta- and entoconids are symmetrical; the transverse crest is wide; the cristid obliqua is weakly developed and is connected with the protolophid at the midline of the tooth; the hypoconulid lophule connects to the metalophid at the midline with a short crest. The morphology of M2 of PREM (1908) specimen from Egypt is simpler than that of the sr^ecimens MAFI V. 11423 and USNM 214596. The latter one has a complicated M2 stmcture developed in different direction than the two others Sirenia indet. II (=Eotheroides sp.) The largest Eocene sirenian mandble (MTM V.72.03) mandbular symphysis is narrower than with E. lihyca; the originates from the Middle Eocene of the Balinka and was symphyseal surface is deflected at about 35° to the ocdusal referred to as "Eotheroides sp." by KORDOS (1980). The plane; there are three larger and one smaller accesory mental