Intergrowth of bryozoans with other invertebrates in the Late Pridoli of Saaremaa, Estonia

Abstract

Nine invertebrates intergrew with bryozoans in the latest Pridoli of Saaremaa, Estonia, namely: cornulitids (Cornulites baranovi and Conchicolites sp.), hydrozoans, rugosans (Tryplasma sp. and Entelophyllum sp.), Anoigmaichnus, microconchids (Tuberoconchus wilsoni), unknown tubicolous organisms and unknown soft-bodied organisms. The most common host of endobionts was Fistulipora przhidolensis, but trepostomes also participated in symbiotic associations. Solitary rugosan-cystoporate and hydrozoan-cystoporate associations were common in the Pridoli of Saaremaa, while other cases of intergrowth are rare. The rugosan-cystoporate, hydrozoan-cystoporate, hydrozoan-trepostome and Anoigmaichnus-cystoporate associations most likely were not a result of accidental intergrowth, whereas other associations presumably resulted from accidental intergrowth of two organisms. New data from the Pridoli of Saaremaa indicate that the Pridoli probably was not a time of lowered symbiosis levels in the regional ecosystem. Symbiosis levels in the Pridoli of Baltica were comparable to those in the Ludlow and Early Devonian worldwide.