A Barrel-Shaped Jurassic Squid Relative Turns Up in Wyoming Fossils

Paleontologists have described a new squid-like animal from the Jurassic that was unusually thick for its kind. According to ScienceAlert, the creature, named Wyoteuthis linsterorum, is known from a pair of fossils pulled from the bed of an ancient inland sea in Wyoming, and the team calls it one of the chunkiest known species in its group.

The finding appears in the journal Papers in Palaeontology. It is the only species so far assigned to the genus Wyoteuthis.

The animal by the numbers

• 2 fossils: The species rests on a pair of specimens. One was found by veteran fossil collector Cliff Linster, who died earlier this year and is honored in the species name.
• About 160 million years old: The fossils date to the Jurassic, when belemnites were plentiful in the seas.
• About 60 mm across: The researchers, led by belemnite expert Alexey Ippolitov, report that the front end of the shell reaches this diameter, the thickest known for belemnites so far.
• 160 to 175 mm long: The specimens are somewhat broken, so this is the team's estimate of the shell's original length based on what remains.
• 55 to 60 cm (22 to 24 inches): Using existing methods for estimating a belemnite's full length, the researchers put the whole animal, from mantle tip to the end of its arms, at roughly this size.

What a belemnite was

Belemnites belong to an extinct order of cephalopods, the group that today includes octopuses and squids. Like modern squids, they had 10 appendages. They also carried a cone-shaped internal shell. Part of that shell was made of aragonite, the same mineral found in the buoyant cuttlebone that sometimes washes up on beaches.

The other part, called the guard or rostrum, was made of calcite. These hard calcite pieces are what usually survive as fossils, and ScienceAlert noted that they are scattered through the Sundance Formation and other deposits around the world.

Why this one stands out

Wyoming has masses of belemnite fossils, but this one looked different. Wyoming paleontologist Bill Wahl, who has searched the state for fossils for much of his career, said the species “stuck out like a sore thumb.” The rostrum is so rotund that the authors themselves describe it as among the chunkiest in the history of the group.

Despite the heavy shell, the animal itself was not necessarily large. The researchers describe Wyoteuthis as a chunky but rather short squid, and they caution that the size of a rostrum does not automatically point to a big animal or one high in the food chain.

The fossils are also rare. The team says the species is only seldom seen in the Redwater Shale Member of the Sundance Formation. One idea they raise is a narrow ecological specialization: the animal may have been picky about its prey or the kind of habitat it lived in.

Why it matters: a rare survivor of a fading family

Wyoteuthis belongs to the family Megateuthididae, which includes Megateuthis, the largest known belemnite. According to ScienceAlert, the family did well after the Toarcian extinction event, a time when the ocean lost vast amounts of oxygen. Creatures that cope well with change can thrive in such conditions, and cephalopods are known for that ability.

Later, in the Middle Jurassic, most megateuthidid lineages died out and other belemnites took their place. The researchers think Wyoteuthis is most likely a portly survivor of a lineage that was otherwise lost over geological time.

For readers, the practical meaning is modest but real. A new species found among well-known fossil beds shows that even heavily studied rocks can still hold unfamiliar animals, and each odd specimen helps researchers piece together which sea creatures lived through the ocean upheavals of the Jurassic and which did not.

The fossils themselves, from a Wyoming sea that disappeared long ago, now carry the name of the collector who helped bring one of them to light.

Around Prague, based on reporting by ScienceAlert