Reference

Royal H. Mapes, R. B. Dalton (2002): Scavenging or Predation? Mississippian Ammonoid Accumulations in Carbonate Concretion Halos Around Rayonnoceras (Actinoceratoidea - Nautiloidea) Body Chambers from Arkansas – Abhandlungen der Geologischen Bundesanstalt in Wien – 57: 407 - 422.