PROLIFIC DEVELOPMENT OF AMPHIASTREIDS AND OTHER PACHYTHECAL CORALS (HEXANTHINIARIA?, SCLERACTINIA?) IN REEFS ON THE ŠTRAMBERK CARBONATE PLATFORM (TITHONIAN-BERRIASIAN)

Abstrakt

The Štramberk Limestone (Moravia, Czech Republic) and the Štramberk-type limestones (Poland) occur in flysch of the Outer Carpathians as olistoliths, blocks and pebbles. They contain the world's most diversified coral assemblages (c. 115 species of 50 genera) in the reefs developed at the Jurassic/

Cretaceous transition. Coral-microbial reefs have been developed primarily in the late Tithonian. In particular, numerous corals occur in the Štramberk Limestone which were studied in the 19th century by Maria Ogilvie and, since the 1960s, extensively studied by Helena Eliášová (see: Eliáš and

Eliášová 1984; Kołodziej et al. 2023). Most characteristic are corals classified to the Pachythecaliina

Eliášová, 1976 (accepted in this presentation), or alternatively to Amphiastreina Alloiteau, 1952, the suborder distinguished earlier. From samples from the Czech Republic and Poland, about 30 genera of pachythecaliine corals were distinguished (mostly with phaceloid growth form). Most of the species and some genera are endemic or rarely described from other countries (coeval coral assemblages typically contain no more than several genera of this suborder). We classify Pachythecaliina to the following families: Amphiastreidae (most common), Carolastraeidae (including some taxa alternatively classified to Heterocoeniidae), Intersmiliidae and Donacosmiliidae. A distinctive feature of these corals is a wall interpreted by most recent authors as a pachytheca (type of epithecal wall), which is developed prior to septa. The bilateral symmetry of the septal arrangement is another distinctive feature. Some discussed corals have poorly developed septa. In the extreme case of wallbased corals - Pachythecophyllia eliasovae (Štramberk-type limestones) - only one strong septum occurs, while others are hardly visible and developed as short septal spines. "Taschenknospung"

(pocket budding) occurring in the Amphiastreidae is not known in other fossil and modern corals.