New 160-million-year-old Jurassic belemnite species described in Wyoming — ScienceAlert

Paleontologists have described a new species of fossil cephalopod mollusk, Wyoteuthis linsterorum, whose remains were found in the US state of Wyoming. Two specimens originate from deposits of an ancient inland sea in the Redwater Shale layer of the Sundance Formation and are about 160 million years old.

As ScienceAlert reports, the new species belongs to belemnites, an extinct order of cephalopod mollusks related to modern squid and octopuses. Belemnites had ten tentacles and an internal cone-shaped shell. Its part, known as the rostrum, was composed of calcite and is well preserved as a fossil.

An unusually thick rostrum

The researchers noted that the rostrum of Wyoteuthis linsterorum is distinguished by its atypically large thickness. Its diameter in the front part reached 60 millimeters, which, according to the study authors, is the largest known measurement among belemnites. The preserved fragments made it possible to estimate the rostrum's length at 160–175 millimeters.

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Using methods for calculating the total length of belemnites, the animal may have reached approximately 55–60 centimeters from the end of the mantle to the tips of the tentacles. At the same time, scientists caution that a large rostrum alone does not mean either a large animal size or a high position in the trophic pyramid.

A rare representative of an ancient group

The species was named in honor of fossil collector Cliff Linster, who found one of the specimens. It is currently the only known species of the genus Wyoteuthis. Scientists suggest that its rarity in the deposits may be linked to narrow ecological specialization, particularly to its type of prey or habitat.

Wyoteuthis was assigned to the family Megateuthididae, which includes Megateuthis, the largest known belemnite. The study authors suggest that the new species may have been a surviving representative of a lineage that largely disappeared in the Middle Jurassic. The description was published in the journal Papers in Palaeontology.