Description: South Australia’s Coober Pedy Opal Field is famous for having fossils that have been replaced by precious opal (hydrous silica - SiO2·nH2O). Recovered opalized fossils from Coober Pedy include bivalves, gastropods, belemnites, crinoids, ichthyosaurs, and plesiosaurs. Here are two examples of opalized belemnites. Belemnites are a group of extinct cephalopods having a squid-like body and a solid, calcareous, internal, elongated, bullet-shaped skeleton called a guard. Two species of Peratobelus belemnites have been reported from the Coober Pedy area: Peratobelus oxys Tenison-Woods, 1883 and Peratobelus bauhinianus Skwarko, 1966. The material shown below appears consistent with Peratobelus oxys. Classification: Animalia, Mollusca, Cephalopoda, Coleoidea, Belemnitida, Dimitobelidae Locality: unrecorded mine field in Coober Pedy Opal Field, north-central South Australia State, southern Australia Stratigraphy: “weathered zone” of the Bulldog Shale, Marree Subgroup, Aptian Stage, upper Lower Cretaceous Some info. from: Williamson, T. 2006. Systematics and Biostratigraphy of Australian Early Cretaceous Belemnites with Contributions to the Timescale and Palaeoenvironmental Assessment of the Australian Early Cretaceous System Derived from Stable Isotope Proxies. Ph.D. dissertation. James Cook University. Townsville, Queensland, Australia. 5+50+25+47+46+9+18+(21) pp. 5 pls. Date: 1 May 2010, 14:30. Source:
Opalized Peratobelus fossil belemnite (Bulldog Shale, Lower Cretaceous; Coober Pedy Opal Field, South Australia) 2. Author:
James St. John.