Middle Triassic lyssacinosan sponges from Upper Silesia (southern Poland), and the history•of hexactinosan and Iychniscosan sponges

Abstract

The allegedly hexactinosan sponges from the Anisian of the Polish part of the Middle Triassic (Muschelkalk) basin have been found to represent two new lyssacinosan genera and species: Hexactinoderma trammeri gen. et sp. n., and Silesiaspongia rimosa gen. et sp. n. It is suggested that the net-like or cubic organization of megascleres known from some Paleozoic forms (regarded as dictyid) are features only superficially resembling, true dictyonal strands known in the Mesozoic and Recent hexactinosan spongs. The lychniscosan sponges are as yet unknown before the Jurassic.