Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 82. (Budapest 1990)
Dulai, A.: The Lower Sinemurian (Jurassic) brachiopod fauna of the Lókút Hill (Bakony Mts., Hungary). Preliminary results
Prionorhynchia greppini (OPPEL, 1861) Prionorhynchia polyptycha (OPPEL, 1861) Prionorhynchia pseudopolyptycha (BÖCKH, 1874) Cirpa ? latifrons (STUR in GEYER, 1889) Ci rpa ? a f f. 1aTTf r • n s Rhynchonellina suessi GEMMELLARO, 1871 Koni nek i na sp . Liospiriferina alpina (OPPEL, 1861) Liospiriferina angulata (OPPEL, 1861) Liospiriferina obtusa (OPPEL, 1861) Liospiriferina obtusa 2. Liospiriferina sicula (GEMMELLARO, 1874) Liospiriferina acuta (STUR in GEYER, 1889) Liospiriferina sylvia (GEMMELLARO, 1878) Liospiriferina aff. brevirostris (OPPEL, 1861) Dispiriferina segregata (DI STEFANO ,1887) Callospi riferi na pinguis (ZIETEN, 1830) Callospiriferina aff. pinguis Zeilleria mutabilis (OPPEL, 1861) Zeilleria alpina ÇÏÏEYER, 1899) Zeilleria choffati (HAAS, 1885) Zeilleria aff. choffati Zeilleria aff. livingstonei GEMMELLARO, 1878 Zeilleria aff. venusta (ÏÏÏÏLIG, 1879) Securina partschi (OPPEL, 1861) Lobothyris punctata (S0WER8Y , 1812) Linguithyris aspasia (MENEGHINI, 1853) Linguithyris linguata (BÖCKH, 1874) Antiptychina rothpletzi (BÖSE, 1894) Bakonyithyris ewaldi (OPPEL , 1861) Bakonyi thyris sp . Phymatothyris sp . Terebratulida sp. This fauna can be considered as the richest Lower Sinemurian fauna of Mediterranean region. It is also remarkable, that on the basis of VDROS's (1983) work, the Bakony Mountains give the richest brachiopod fauna of Mediterranean region in Pliensbachian also. In both cases the exceptionally exact collection work stands in the background. Palaeoecological examinations- I made my examinations bed-by-bed , then I averaged the four intervals. The change of specimen number and taxon number of the brachiopods are. very extreme (Fig. 3). The specimen number and taxon number are prominently high in the 2nd and 3nd layer and in the D interval. The two graphs have very similar forms, but in the B and C interval the taxon number is low even in the beds with relatively high specimen number, i.e. the diversity of the fauna considerably decreases . Making examination on the enclosing rock, we can conclude to the depositional environment. The Pisznice Limestone is a 15 m thick, thinly bedded, pinkish-reddish crinoidal limestone. The filling material of brachiopods often differs from the material of enclosing rock, which suggests resedimentation. It is supported by the high disintegration of bivalves and brachiopods, and by the gradation we can observe in some layers. The disintegration ratio of the brachiopod valves, i.e. the ratio of isolated valves can be seen in Fig. 4. Owing to their locking mechanism, the brachiopods hardly disintegrate after death, on the contrary to the bivalves. The passively operating ligament opens the two valves of bivalves after the relaxation of the adductor. On the other hand, active diductor muscles are needed to open the valves of the brachiopods. Inner teeth and sockets control the turn of the valves along the axis of rotation. Owing to the strong connection of teeth and sockets, the two valves usually remain together during fossilization . Such high, often 100% disintegration ratio is probably resulted from an external mechanical influence during resedimentation .
