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Niobrara Formation

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The Niobrara Formation is geologic formation deposited during the Late Cretaceous in what is now the Great Plains region of the US and Canada. It is one of several formations that show evidence of the Western Interior Seaway within North America. The formation is named after the Niobrara River in Nebraska, where the formation's type location is found.

Stratigraphy[]

The rocks of the Niobrara Formation are limestones, which formed due to the accumulation of coccolithophore microfossils. The formation is often broken up into two smaller units, those being the older Fort Hays Limestone Member and the younger Smoky Hill Chalk Member. The Fort Hays Limestone is composed of massive (lacking sort of layering or foliation) limestone beds, while the Smoky Hill Chalk Member is primarly made up of chalk and is where most of the fossils discovered in the formation are from. The Niobrara Formation overlies the Carlile Formation and underlies the Pierre Shale.

Paleobiota of the Niobrara Formation[]

Invertebrates[]

Bivalves[]

Cephalopods[]

Echinoderms[]

  • Uintacrinus

Fish[]

Chondrichthys (cartilaginous fish)[]

Osteichthys (bony fish)[]

Dinosaurs[]

Ornithiscians[]

Theropods[]

Pterosaurs[]

Mosasaurs[]

Plesiosaurs[]

Turtles[]

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