Fossil cephalopods are frequently encrusted by epibionts;however,determining whether encrustation occurred prior to or post-mortem to the host,and whether the final environment of deposition corresponds to the habitat...Fossil cephalopods are frequently encrusted by epibionts;however,determining whether encrustation occurred prior to or post-mortem to the host,and whether the final environment of deposition corresponds to the habitat of encrustation is complex.The present paper describes cirripede epibionts,their calcareous bases and their attachment scars on 6 post-mortem shells of Nautilus macromphalus,collected from deep water off New Caledonia.The cirripedes have left both cemented calcareous bases of Hexelasma and scars associated with bioerosion and discoloration produced by verrucomorph barnacles.Live cirripedes included a Metaverruca recta,with articulated opercular plates and organic tissue(on a shell that had been exposed on the sea floor for at least 150 years),and specimens of Hexelasma velutinum,one of which was partly attached to an internal surface of a shell.The disposition of verrucomorphs indicates that most Nautilus shells were colonized post-mortem rather than during a floating stage.However,as cirripedes are known to have colonized living Nautilus,some Hexelasma,preserved only as calcareous eroded bases,may represent specimens that settled on a living Nautilus.The degree of bioerosion and discoloration induced by verrucomorph barnacles varies according to the surface preservation of Nautilus shells,with deeper and discolored traces preserved on old and degraded shells.Traces made by verrucomorphs described here are ellipsoidal and a new ichnotaxon,Anellusichnus ellipticus,is proposed to accommodate them.Importantly,verrucomorphs and other cirripede taxa with membranous bases that were attached to pristine shells may not leave any substantial scars,and,thus,will be difficult to detect in the fossil record.展开更多
基金the Ministry of Culture of the Czech Republic(IP DKRVO 2019/2.III.a,National Museum,00023272)MKVs research was supported by the Center for Geosphere Dynamics(UNCE/SCI/006)+1 种基金by the RVO 67985831 of the Institute of Geology of the Czech Academy of Sciences.JS and AT were funded by the Slovak Scientific Grant Agency(VEGA 2/0169/19)by the Slovak Agency for Research and Development(APVV 17-0555).
文摘Fossil cephalopods are frequently encrusted by epibionts;however,determining whether encrustation occurred prior to or post-mortem to the host,and whether the final environment of deposition corresponds to the habitat of encrustation is complex.The present paper describes cirripede epibionts,their calcareous bases and their attachment scars on 6 post-mortem shells of Nautilus macromphalus,collected from deep water off New Caledonia.The cirripedes have left both cemented calcareous bases of Hexelasma and scars associated with bioerosion and discoloration produced by verrucomorph barnacles.Live cirripedes included a Metaverruca recta,with articulated opercular plates and organic tissue(on a shell that had been exposed on the sea floor for at least 150 years),and specimens of Hexelasma velutinum,one of which was partly attached to an internal surface of a shell.The disposition of verrucomorphs indicates that most Nautilus shells were colonized post-mortem rather than during a floating stage.However,as cirripedes are known to have colonized living Nautilus,some Hexelasma,preserved only as calcareous eroded bases,may represent specimens that settled on a living Nautilus.The degree of bioerosion and discoloration induced by verrucomorph barnacles varies according to the surface preservation of Nautilus shells,with deeper and discolored traces preserved on old and degraded shells.Traces made by verrucomorphs described here are ellipsoidal and a new ichnotaxon,Anellusichnus ellipticus,is proposed to accommodate them.Importantly,verrucomorphs and other cirripede taxa with membranous bases that were attached to pristine shells may not leave any substantial scars,and,thus,will be difficult to detect in the fossil record.
