Fossilized soft tissues in Palaeozoic bryozoans

Abstract

Thin sections of three Palaeozoic bryozoans reveal fossilized soft tissues that show the position of organic cuticle and internal structures such as the membranous sac and gut. The fossilization occurred apparently due to fast burial under anoxic conditions. The position of a membranous sac in the Permian trepostome Rhombotrypella superangustata is indicative of a progressive polypide cycle. The position of the polypide in the Ordovician Graptodictya delicata behind the superior and interior hemisepta suggests a protective function of the hemisepta.

A new genus and species of cornulitid tubeworm from the Hirnantian (Late Ordovician) of Estonia

“…Nield (1984) suggested that, in addition to selecting favorable water currents, larvae of the Trypanites producers concentrated on topographic highs. With gradual sedimentation, topographic highs would be exposed longest, allowing more time for bioerosion (Nield, 1984; Knaust et al, 2023). There are reefs in the Ärina Formation in Reinu quarry, and bioerosion is not common in the reef facies in the Ordovician Basin of Estonia (Toom, 2019).…”