Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 24-25. 2007. (Budapest, 2007)

Figure 11 — Distribution of drill holes on Argyrotheca Figure 12 — Distribution of drill holes on Argyrotheca cuneata (RlSSO, 1826) specimens. Circle diameters are cordata (RlSSO, 1826) specimens. Circle diameters are proportional with the observed drill hole sizes. proportional with the observed drill hole sizes. Conclusion More than 400 specimens of Middle Miocene micromorphic brachiopods yielded three species of Megathyrididae {Megathiris detruncata, Argyrotheca cuneata, A. cordata) from two localities of the Bakony Mts. These three species are common in the shallow w

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ater environments both in fossil and Recent assemblages. Until now, all the three species were represented by only few specimens in the Hungarian Miocene fossil record (BlTNER & DULAI 2004). The high percentage of complete, well-preserved shells at Bánd suggests that the studied assemblage is more or less autochtonous, without significant transportation, selective removal of smaller specimens or mechanical destruction. All of the Devecser brachiopods are isolated valves, but the good preservation refers only to short transport. The two Argyrotheca species are sufficiently numerous in the examined material for size-frequency distribution studies. Both A. cuneata and A. cordata show bell-shaped size-frequency histograms, indicating low juvenile mortality. It corresponds well with other data from Miocene and Recent reef-associated micromorphic brachiopod assemblages. Argyrotheca specimens lived in protected, cryptic environments of the reef. Patchy larval distribution resulted in unimodal, bell-shaped size distribution, suggesting stable community. Recent data indicate that nearly all of the Bánd specimens belong to young adult and mature brachiopods. Epifaunal encrusters are recorded for the first time on the micromorphic brachiopods in the Central Paratethys. Three brachiopods (0.7 %) carry epibionts on their valves (1 Bryozoa and 1 serpulid on A. cordata and 1 serpulid? on A. cuneata). Both the Bryozoa {Annectocyma?) and the serpulid situated on the ventral valves near to the anterior margin, which is the highest point of the Argyrotheca valves in life position. It suggests that these epizoans encrusted the ventral valves during the life of these brachiopods. The serpulid probably benefitted from the feeding currents of the brachiopod. Fifteen out of 422 Argyrotheca specimens show drill holes of predatory gastropods (3.5%). No taxon selectivity- can be observed {A. cordata: 3.6%; A. cuneata: 3.4%). Valve selectivity to ventral valve's advantage is more significant in the case of A. cuneata (80%—20%). Ventral valve selectivity suggests that predatory gastropods attacked the living brachiopods, because the ventral valve was more accessible in life position. Site selection is also present at A. cuneata. As both muricid and naticid gastropods were diverse and abundant at Bánd locality, it is impossible to identify the predator species. * * * Acknowledgements — The author is grateful to the two amateur collectors, Tamás NÉMETH and Tibor BERTA for offering their brachiopod material to study and publish. Many thanks to Dr. Maria Aleksandra BlTNER (Poland) for useful discussions on brachiopods and to Dr. Attila VÖRÖS (Budapest) and Dr. M. A. BlTNER (Poland) for critical reviewing of the manuscript. Hungarian Scientific Research bund (OTKA T 49224) and János Bolyai Research Grant supported this work. Thanks to Dr. Piroska PAZONYI for preparation of the locality map. References ASGAARD, U. (1986): Paedomorphosis in brachiopods: response to stressfull environments? — In: RACHEBOEUF, P. R. & EMIG, C. (eds): Les brachiopodes fossiles et actuels. — Biostratigraphie du Paléo-^oique, 4: 43-46. A.SGAARD, U. & BROMLEY, R. G. (1991): Colonization by micromorphic brachiopods in the shallow subtidal of the eastern Mediterranean Sea. — In: MACKINNON, D., I., LEE, D. E. & CAMPBELL, J. D. (eds): Brachiopods through time. — Balkema, Rotterdam, 261-264. BÄRBULESCU, A. & RADO, G. (1984): Contributions à la connaissance des brachiopodes badéniens de Roumanie. — 75 years of the I Mhoratory of Paleontology, Special Volume: 173-184. BARCZYK, W. & Poi'llü.-BARC/.VK, E. (1977): Brachiopods from the Korytnica basin (Middle Miocene; 11 oly Cross Mountains, Poland). — Acta Geologica Polonica, 27(2): 157-167. BAUMILLER, T. K. & BlTNER, M. A. (2004): A case of intense predatory drilling of brachiopods from the Middle Miocene of southeastern Poland. — Pa/aeogeography, Palaeoclimatology, Palaeoecology, 214: 85—95. BERTA, T. & NÉMETH, T. (2004): Bánd (Veszprém m.) templom DK, 200m terület faunakutatása. [Study of the fossil fauna of Bánd (Veszprém County), 200m SE of the church|. — Bakony Natural History Museum, Zirc, pp. 1-11. [manuscript, in Hungarian]. BlTNER, M. A. (1990): Middle Miocene (Badenian) brachiopods from the Roztocze Hills, south-eastern Poland. —Acta Geologica Polonica 40(3-4): 129-157. BlTNER, M. A. (1993): Middle Miocene (Badenian) brachiopods from coral reefs of north-western Bulgaria. — Acta Geologica Polonica 43(1-2): 147-155. BlTNER, M. A. (1996): Encrusters and borers of brachiopods from the La Meseta Formation (Eocene) of Seymour Island, Antarctica. — Polish Polar Research, 17(1-2): 21-28. BlTNER, M. A. (2002): Size-frequency distributions of Miocene micromorphic brachiopods: interpretation tool for population dynamics.