North Dakota Stratigraphy Tusoteuthis longa ROCK ROCK UNIT COLUMN PERIOD EPOCH AGES MILLIONS OF YEARS AGO Common Name: Holocene Oahe .01 Giant squid

Coleharbor Pleistocene QUATERNARY Classification: 1.8 Pliocene Unnamed 5 Miocene Class: Cephalopoda 25 Arikaree Order: Teuthida Family: Kelaenidae Brule Oligocene

38 South Heart Chadron Chalky Buttes

Camels Butte Eocene Golden 55 Valley Bear Den Pen (hard support structure) of the giant squid, Tuseteuthis, Sentinel Butte superimposed on a sketch of the squid. Pen is 2 meters long. TERTIARY Cretaceous Pierre Shale. Cavalier County. North Dakota State Fossil Collection.

Bullion

Paleocene Creek Description: Tusoteuthis longa was a giant squid that inhabited the Pierre Sea Slope that covered North Dakota about 80 million years ago. These

Cannonball ancient squids had a rigid support structure in their body called a

Ludlow pen or gladius. The pen was in many ways similar to a back bone 65 but made of shelly material and not bone. The pens are found as Hell Creek fossils. Some of these squids grew to lengths of 15 feet or more. They lived in the Pierre Sea with sharks, mosasaurs, and many Fox Hills other animals.

ACEOUS Pierre CRET

84 Niobrara

Carlile

Carbonate Calcareous Shale Claystone/Shale

Siltstone Sandstone Sand & Gravel

Mudstone Lignite Glacial Drift

Giant squid, Tusoteuthis, battleing a mosasaur. Image from the Morden Museum, Morden, Manitoba

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