|Photo :© Alias Collections|
Opalized Belemnite | #Geology
Belemnitida is an extinct order of cephalopods which existed during the Mesozoic era, from the Hettangian age of the Lower Jurassic to the Maastrichtian age of the Upper Cretaceous. The belemnite is the state fossil of Delaware.
Belemnite remains are found in what were littoral (nearshore) and mid-shelf zones. Squid and octopuses diversified and began to outcompete belemnites by the Late Jurassic to Early Cretaceous. Belemnites declined through the Late Cretaceous, and their range became more restricted to the polar regions; the southern populations became extinct in the early Maastrichtian, and the last belemnites—of the family Belemnitellidae—inhabited what is now northern Europe. They finally became extinct in the Cretaceous–Paleogene extinction event, around 66 mya, where, like in ammonites, it is thought the protoconch of embryos could not survive the ensuing acidification of the oceans
Upper Cretaceous, 95 million years,
provenance: Coober Pedy, Australia.