TY - JOUR A1 - Thomka,J.R. A1 - Bantel,T.E. T1 - Sequential, multi-taxon encrustation of an orthoceratid cephalopod by stalked blastozoan echinoderms in the middle Silurian (Wenlock Series) of southeastern Indiana, USA JF - Bulletin of Geosciences JA - Bull. Geosci. Y1 - 2021 VL - 96 IS - 1 SP - 53 EP - 59 CY - Prague PB - Czech Geological Survey SN - 1803-1943 (online), 1802-6222 (print) AV - Free KW - Diploporita KW - Rhombifera KW - Massie Formation KW - Sheinwoodian KW - biotic interactions KW - attachment structures AB - An orthoceratid cephalopod serving as a substratum for rare encrustation relationships is herein described from the middle Silurian (Wenlock Series, Sheinwoodian Stage) Massie Formation of southeastern Indiana, USA. The partial orthoconic cephalopod phragmocone is preserved as a flattened internal mold with some remnant shell material. The more damaged (presumably upward-facing) side is encrusted by the thecal attachment structure of a trematocystinid holocystitid diploporitan (probably Paulicystis), which is, in turn, encrusted by a dendritic attachment structure attributable to the hemicosmitid rhombiferan Caryocrinites. This represents an unusual form of multigenerational encrustation by blastozoan pelmatozoans; an encrustation that did not culminate in overgrowth of the cephalopod substratum. More importantly, this occurrence demonstrates preferential use of echinoderm remains as settling sites for later encrusting echinoderms, despite class-level taxonomic differences, and represents an additional example of utilization of a discrete macrofossil - and a rarely reported example of a coeval echinoderm attachment structure - as a substratum for Caryocrinites attachment. Collectively, this material indicates that pelmatozoan encrustation of bioclasts in otherwise softground substrates is controlled by more complex factors than mere occurrence of available biomineralized material. ER -