Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 89. (Budapest 1997)

Vremir, M., Codrea, V. ; Farkas, B.: Trionyx stiriacus Peters, 1855 (Reptilia, Testudines) from the Sarmatian (Middle Miocene) of Minişu de Sus (Romania)

coming prolonged caudally. Of all neural plates, N 6 is the only one preserved, the others occur as imprints. Generally, they have a prolonged-oval or rhomboid shape, enlarged in the caudal (N 3-5) or cranial (N 6-7) parts, the reversal of neural orientation involves a sequential pair of asymmetrical pentagonal plates. The neural file N 4-7 is 101 mm long. Its excentric aspect as related to the anteroposterior axis of the plates N 5-6, is regarded merely as an individual variation (cf. PRITCHARD 1988, GARDNER & RUSSELL 1994). This carapace originally must have had a subcircular, slightly vaulted outline and a total length of approximately 290-300 mm. The fragment of the hypoplastron represents the distal section, with four median-posterior digited apophyses, two of them being grouped into a single one, broader than the others. The caudal margin is preserved at a length of 50 mm, the exterior apophyses enclose an angle of approximately 80°. TCM 8377 (Fig. 5) - The carapace imprint presents an incomplete caudal part. The left antero-lateral section is also damaged. This specimen has a subcircular outline. Characteristically, the ribs are strongly developed and the free ends generally represent about 1/3 of the pleurals' length. The outline of the bony disk has a scalloped aspect, showing prominences at the level of the rib ends, which are prolonged, generally tapering, with widths of 10-12 mm and lengths of 20-25 mm. The first pleural is of a trapezoidal shape, strongly curved in the anterior sense. The other pleurals have prolonged-pentagonal shapes, with their points in the distal extremities where they also show moderate enlargements, decreasing towards P 4. Beginning with P 5, the pleurals are progressively curved caudally. The last pair is not preserved. The maximal dimensions of the bony disk are 115/115 mm CL and 140/155 mm CW, including the free ends of the ribs (index CL/CW = 0.90). Of the neural file, several parts of the thoracic vertebrae are preserved, broken at the level of the neural duct, lacking the proper plates. The file N 1-7 is 85 mm long. Whether the very first element in the median series is actually a preneural or an unusually positioned fragment of the nuchal is impossible to define on the basis of the available material. COMPARISON AND DISCUSSION The sole record of the genus Trionyx (sensu lato) from the Sarmatian stage in Romania is from Reghiu (Vrancea district). MACAROVICI & MoTAS (1965) described a specimen from this horizon, identified with some hesitation as T. pliopedemontanus SACCO, 1889 - in our opinion an indeterminable trionychid. The most significant differences between this one and the specimens found at Minis, include the longitudinal subdivision of the nuchal in three segments (also present in the Miocene taxa T. petersi HOERNES, 1881 and T. sophiae HERITSCH, 1909, and the Oligocène 77. insolitus BERGOUNIOUX, 1954), as well as the morphology of the first neural. These characteristics suggest that the specimen from Vrancea and T. petersi, a species commonly assigned to the T. stiriacus group (HUMMEL 1929, BROIN 1977), are conspecific. Yet, the age of the deposits at Vrancea where the carapace remains originate from is more recent (Kersonian = Upper Sarmatian). Also Trionyx moldaviensis KHOZATSKI, 1986 was described from the Upper Sarmatian, from Malye Mileshty, Moldavian Republic, and is likely a junior synonym of 77. brunhuberi AMMON, 1911 (cf. CHKHIKVADZE 1980). In turn, however, the latter species is listed as a synonym of T. hoernesi HERITSCH, 1909 by HUMMEL (1929). Trionyx hoernesi, described from the Middle Miocene of the Vienna Basin is, according to certain authors (e.g. HUMMEL 1929, BROIN 1977), a species to be allocated to