Wyoteuthis linsterorum had the thickest known belemnite guard and belonged to a family scientists thought had died out millions of years earlier.

Fossil collectors in Wyoming have a blunt nickname for the bullet-shaped remains of belemnites, ancient relatives of squid that turn up by the millions in the state's Jurassic rocks. "Squid butts," as paleontologist Jessica Lippincott says locals call them, are usually slim and unremarkable — but two oddly fat ones have now been named a new species.

The animal, Wyoteuthis linsterorum, lived about 160 million years ago in a shallow sea that once covered Wyoming, according to a study in the journal Papers in Palaeontology. Its fossilized guard is the thickest of any known belemnite, and CT scans tie it to a family scientists believed had vanished millions of years earlier.

Both specimens are on public display at the Wyoming Dinosaur Center in Thermopolis, giving road-trippers and families a rare chance to see a brand-new species in person.

A Squid Butt That Stuck Out Like a Sore Thumb

Belemnites looked broadly like modern squid, with arms and a soft body, but they also had a hard internal guard called a rostrum. That bullet-shaped piece is what usually fossilizes, and its pointed tip gave rise to the local nickname.

Typical Wyoming belemnites have rostra about 2 to 4 inches (5 to 10 centimeters) long and less than an inch (1 to 2 centimeters) across. The new species' rostrum is about 4 inches (10 centimeters) long but up to 2.4 inches (6 centimeters) wide, according to the University of Manchester. Researchers estimate the whole animal, arms included, reached about 2 feet (60 centimeters).

Paleontologist Bill Wahl, who launched the study, said the fossil "stuck out like a sore thumb" among the countless belemnites collected in the region. "It goes to show that we are still finding new species of fossils all the time," Lippincott said. "Wyoteuthis is significantly bigger than any other," she told Cowboy State Daily.

The researchers were confident enough in its bulk to title their paper "The big chunky belemnite." The team spans the United States, the United Kingdom, and New Zealand, and its CT work let them look inside the rostrum without cutting the rare specimens apart.

A Relict Family That Outlived Its Expected Exit

The bigger surprise came from inside the fossils. CT scans linked Wyoteuthis to the megateuthidids, an ancient belemnite family scientists thought had disappeared millions of years before this animal lived. The paper calls it a relict megateuthidid, meaning a late survivor of an older lineage.

Alexey Ippolitov, a belemnite specialist now at Victoria University of Wellington in New Zealand, said he was "deeply surprised" by the specimen. The team suggests its size gave it an edge as a predator, possibly hunting smaller belemnites of the genus Pachyteuthis that shared its sea. Ippolitov said "their relatively large size gave them an advantage when hunting co-occurring smaller belemnites," noting that modern squid readily prey on other cephalopods, sometimes even their own kind.

"Perhaps its rarity is a result of narrow specialization," said co-author Dean Lomax, an honorary research fellow at the University of Manchester, as reported by ScienceDaily. That would help explain why only two specimens have turned up among millions of ordinary belemnites.

Evidence check: the species rests on two specimens, and the 2-foot body length is an estimate based on the rostrum, since soft parts were not preserved. The idea that it preyed on smaller belemnites is a hypothesis drawn from its size, not direct evidence such as stomach contents. The paper was published in September after peer review.

From a Museum Drawer to a Family Name

The first specimen was found in the late 1990s by Burkhard Pohl, founder of the Wyoming Dinosaur Center, and sat unstudied in a museum drawer for years. The second came from fossil collector Cliff Linster, who found it near Ten Sleep and donated it to the center in 2019.

Linster died June 10 at age 82, before the paper was published, Cowboy State Daily reported. The species name honors him and his family. "I'm honored to have an extinct giant squid bear our family name," said his son, Wes Linster. Lomax said it was "bittersweet" that Linster did not see the study in print.

Both fossils come from the Sundance Formation, rock laid down by a shallow inland sea that crossed Wyoming in the Jurassic. That ancient seaway explains why marine fossils turn up today — sometimes by the millions — in ranch country hundreds of miles from any ocean.

Seeing the Fossils and Collecting Responsibly

The Wyoming Dinosaur Center in Thermopolis displays both Wyoteuthis specimens. One of them was found on the Hot Springs Ranch near Thermopolis, close to where it is now displayed, Cowboy State Daily reported. Thermopolis sits in the Bighorn Basin, and visitors should check the center's seasonal hours before making the drive as fall turns to winter.

For amateur collectors, this find is a reminder that ordinary-looking fossils can matter. If you find something unusual, photograph it in place, note the location, and contact a museum or university paleontologist. Always confirm who owns or manages the land before collecting, since rules differ for private ranches, state land, and federal land, and some sites require permits.

The people with the most at stake are Wyoming's museums and volunteer collectors, whose donations keep making discoveries possible. The bottom line is that a nickname-worthy fossil turned into a scientific surprise, and anyone curious can see it in person in Thermopolis.

What Readers Want to Know

What is Wyoteuthis linsterorum?

A newly named belemnite, an extinct squid relative, that lived about 160 million years ago in a shallow sea over Wyoming.

Why do people call belemnites squid butts?

Wyoming fossil hunters use the nickname for the bullet-shaped rostrum, the hard internal guard that usually fossilizes.

How big was it?

Its rostrum was about 4 inches long and up to 2.4 inches wide, the thickest known. The whole animal was likely about 2 feet long.

What makes it scientifically surprising?

CT scans place it in the megateuthidid family, which scientists thought had disappeared millions of years earlier.

Where can I see the fossils?

Both specimens are on display at the Wyoming Dinosaur Center in Thermopolis, Wyoming.

Can I collect belemnites myself?

Check land ownership and rules first. Private land requires permission, and public lands have their own regulations.