High Quality Content by WIKIPEDIA articles! Belemnotheutis (sometimes misspelled Belemnoteuthis) is an extinct genus of cephalopods which existed from the Middle to Upper Jurassic (164.7 to 150.8 million years ago). They are related to belemnites but differ significantly in morphology. Belemnotheutis fossils are some of the best preserved among coleoids. Remains of soft tissue are well-documented in some specimens, even down to microscopic muscle tissue. In 2008, a group of paleontologists recovered ink chambers of several specimens that still contained viable ink.