OPALIZED Peratobelus BELEMNITES
In addition to opalized clams, South Australia’s
Coober Pedy Opal Field also contains fossil belemnites that have been replaced
by precious opal (hydrous silica - SiO2·nH2O).
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
Opalized Peratobelus belemnite (polished), Bulldog Shale, upper Lower Cretaceous;
Coober Pedy Opal Field, north-central South Australia. Specimen owned by
John Medici.
Opalized Peratobelus belemnite (polished), Bulldog Shale, upper Lower Cretaceous;
Coober Pedy Opal Field, north-central South Australia.
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.