South Australia’s Coober Pedy Opal Field is famous for having fossils that have been replaced by precious opal (hydrous silica - SiO2·nH2O).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 is an example of an opalized belemnite.

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 above 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.

See info. at: <a href="https://en.wikipedia.org/wiki/Belemnitida" rel="nofollow">en.wikipedia.org/wiki/Belemnitida</a> and