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Triassic Dasycladales from the reefeal facies: examples from NW Croatia

Although the majority of fossil (as well as living) Dasycladales inhabited the protected shallow marine environments as lagoons and bays, there are examples of dasyclads that tolerate, and even prefer the reefeal agitated environment. Here are presented some examples from the Anisian of NW Croatia. The first example is reef limestone from the Belski dol quarry, characterised by peculiar "psudooncoidal" reef cements, similar to "Evinosponge" described from the Ladinian Esino Limestone of Lombardia (N Italy) (JADOUL & FRISIA 1988). The species that are usually found in the lagoonal carbonates are present in this limestone: Oligoporella pilosa PIA, Physoporella pauciforata (GÜMBEL) PIA, Physoporella varicans PIA, Teutloporella peniculiformis OTT, Macroporella alpina PIA and foraminifera Meandrospira dinarica KOCHANSKY-DEVIDÉ & PANTIC. Beside them, there is one dasycladal alga that was completely adapted to the reef environment, living attached to the reef rock: Scinderella scopuliformis GRGASOVIC & SOKAC (GRGASOVIC et al., in press). The second example is Ocura quarry, where reefeal limestones are resedimented into deeper-water tuffaceous sediments. The most common reef-organism is sphinctozoan sponge Celyphia zoldana OTT, PISA & FARABEGOLI, acting as framework builder, baffler and encruster. Besides it, there are many other, mainly encrusting microfossils. In several samples, probably from the back-reef facies, dasyclad Diplopora nodosa SCHAFHÄUTL is found together with problematic encrusting fossil (sponge?, alga?) Olangocoelia otti BECHSTÄDT & BRANDNER. Similar reefeal environments from the Ladinian Wetterstein Limestone of the Northern Calcareous Alps has been described by OTT (1972), and from the Anisian of Northern Dolomites by SENOWBARI-DARYAN et al. (1993).

green algae; Dasycladales; Triassic; reef; paleoecology

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