Rusophycus inexpectus isp. nov. from the Furongian (Upper Cambrian) of the Holy Cross Mountains (Poland)

Abstract

A new trace fossil Rusophycus inexpectus isp. nov. is described from the Furongian (Upper Cambrian) strata of the Holy Cross Mountains. This ichnospecies is probably non-trilobite in origin and is commonly preserved as an undertrace. This preservation style resembles that of Rusophycus ramellensis Legg, an index fossil of the Cambrian Series 3. Therefore, previous workers misinterpreted material from the Wiśniówka Sandstone Formation as Rusophycus ramellensis Legg (recorded by them as Cruziana barbata) and put the Cambrian Series 3 and Furongian boundary within this unit. Rusophycus inexpectus isp. nov differs from Rusophycus ramellensis Legg: 1) in having a smooth trapezoidal area behind the lobes; 2) in the presence of a direct contact between the endopodal lobes and cephalic margin imprints and 3) in the restriction of the occurrence of the endopodal lobes and scratches to the cephalic region of the trace fossil. Care must be taken, when dealing with the undertrace preservation style of Rusophycus ramellensis Legg in other assemblages, as it may represent Rusophycus inexpectus isp. nov.