Knightoconus Knightoconus antarcticus is an extinct species of fossil monoplacophoran from the Cambrian Minaret Formation of Antarctica. It is thought to represent an ancestor to the cephalopods. It had a chambered conical shell, but lacked a siphuncle. 21063141 1020415702 Yochelson et al., 1973 ~ artistic reconstruction of Knightoconus antarcticus Yochelson et al., 1973 Knightoconus antarcticus Knightoconus antarcticus is an extinct species of fossil monoplacophoran from the Cambrian Minaret Formation of Antarctica. It is thought to represent an ancestor to the cephalopods. It had a chambered conical shell, but lacked a siphuncle. 4124
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