Coral-crinoid biocoenosis and resulting trace fossils from the Middle Devonian of the Eifel Synclines (Rhenish Massif, Germany)

Abstract

<jats:p>Fossil echinoderms are a rich source of information concerning biotic interactions. In this study we analyzed the premortem encrustation of the highly specialized Middle Devonian rugose corals<jats:italic>Aspasmophyllum crinophilum</jats:italic>and ?“<jats:italic>Adradosia</jats:italic>” sp. on camerate crinoid stems.<jats:italic>Aspasmophyllum</jats:italic>infested living crinoid stems by sclerenchymal outgrowth that formed a skeletal ring but ?“<jats:italic>Adradosia</jats:italic>” sp. encrusted the stems rapidly, without building a ring. These coral-crinoid biocoenoses indicate a settlement advantage for the rugose corals within densely populated communities of the lower Givetian. The corals could be interpreted as large epizoozoans that benefited as secondary tierers reaching relatively high tiering levels. It also suggests the ability for the affected crinoids to repel the coral by overgrowing the corallite with a local increased stereomic growth. Because the crinoid axial canals are not penetrated, the corals cannot be considered as predators or parasites of crinoids. Therefore, the described biocoenosis is interpreted as commensalism. The species<jats:italic>A. crinophilum</jats:italic>is redescribed, and a neotype is defined, because of the loss of the initial types. Two types of ichnofossils can be attributed to the premortem encrustation of both corals. They are described as<jats:italic>Ostiocavichnus</jats:italic>n. ichnogen. and are attributed to the stereomic response of the infested hosts. These swellings are characterized as either elliptical (<jats:italic>Ostiocavichnus ovalis</jats:italic>n. ichnogen. n. ichnosp. due to the assumed reaction of<jats:italic>A. crinophilum</jats:italic>) or subcircular concavities (<jats:italic>O. rotundatus</jats:italic>n. ichnogen. n. ichnosp. due to the reaction of ?“<jats:italic>Adradosia</jats:italic>sp.”).</jats:p>

Echinoderm ichnology: bioturbation, bioerosion and related processes

“…Finally, the ichnogenus Ostiocavichnus was erected by Bohatý et al (2012) from Devonian crinoids of Germany and Poland. It comprises gall-like swellings produced on crinoid pluricolumnals by epizoozoan rugose corals.…”

“…It comprises gall-like swellings produced on crinoid pluricolumnals by epizoozoan rugose corals. These traces consist of elliptical or subcircular concavities resulting from the encasing of the coral by stereomic coating (Bohatý et al, 2012).…”

A swollen crinoid pluricolumnal from the Upper Ordovician of northern Kentucky, USA: the oldest record of an amorphous paleopathologic response in Crinoidea?; pp. 317–322

“…A diverse fauna of organisms directly associated with ancient crinoids is also inferred from the fossil record (Meyer & Ausich 1983). This interpretation is supported by the presence of encrusting epibionts (e.g., Głuchowski 2005); parasitic or commensal organisms positioned over the anal vent or between the arms of crinoids (e.g., Bowsher 1955;Donovan 1991a;Bohatý et al 2012); regenerated arms, columns and spines (e.g., Oji 2001;Baumiller & Gahn 2004;Gahn & Baumiller 2005); organisms contained within pits in crinoid stems (e.g., Franzén 1974;Warn 1974;Welch 1976); and predatory or parasitic borings and embedment structures (e.g., Brett 1978Brett , 1985Baumiller 1990). Yet, malformed (swollen) crinoid material may represent the most convincing reflection of a response to an ancient biotic interaction.…”

Earliest known rugosan-stromatoporoid symbiosis from the Llandovery of Estonia (Baltica)

“…was an endobiont within the tabulate coral Paleofavosites prolificus in the Llandovery of Ohio (Sorauf and Kissling, 2012). Living crinoid stems were infested by rugose corals in the Devonian of Morocco and Germany (Berkowski and Klug, 2011;Bohatý et al, 2012). However, the cases of symbiosis between rugosans and stromatoporoids (Kershaw, 1987;Vinn and Mõtus, 2014a) seem to be more common than the other associations in the Palaeozoic.…”