A new species of belemnite — an extinct relative of today’s cuttlefish and squid — has been identified from two bullet-shaped fossils found in Wyoming, the United States. Named Wyoteuthis linsterorum, it belongs to a family that was supposed to have vanished some 20 million years before the animal lived.
Wyoteuthis linsterorum. Image credit: Jason Poole.
Belemnites swam in Jurassic and Cretaceous seas. They had soft bodies, but the part that fossilizes is the rostrum, a dense, pointed, calcite structure at the rear of the body, thought to have helped counterbalance the animal in the water.
The fossilized rostra of Wyoteuthis linsterorum were discovered in the Sundance Formation, which records a shallow seaway that covered parts of the western United States about 160 million years ago (Late Jurassic).
“Most Wyoming belemnites are bullet-shaped measuring around 5 to 10 cm (2-4 inches) long and only 1 to 2 cm (0.4-0.8 inches) wide,” said Victoria University of Wellington Ph.D. student Alexey Ippolitov and his colleagues.
“By contrast, the newly discovered species had an unusually broad, barrel-shaped rostrum around 10 cm long but up to 6 cm (2.4 inches) wide, making it the thickest belemnite ever recorded.”
Because the fossils were packed with hardened sediment, the paleontologists used CT scans to study their internal structure.
Along with the rostrum’s shape, the angle of its internal cavity, and fine grooves and striations near its tip, this led them to assign the creature to the family Megateuthididae.
Megateuthidid belemnites flourished in the Early and Middle Jurassic and were long thought to have gone extinct around the Bathonian age, about 166 million years ago.
The researchers propose that Wyoteuthis linsterorum descended from an older genus called Brevibelus, and that it points to a previously unrecognized refuge for the family in the northeastern Pacific.
“I was deeply surprised to discover a fossil from such a well-studied group that differed so radically from anything previously known,” Ippolitov said.
“After more than 200 years of paleontological research on belemnites, discoveries like this are exceptionally rare.”
The scientists suggest Wyoteuthis linsterorum may have been highly specialized, or may have lived mainly along the open-ocean shelf and only occasionally wandered into the Sundance Sea.
“After spending years fossil hunting in Wyoming and collecting countless fossils of the common Pachyteuthis belemnites here in Wyoming, this one is unlike anything I have ever seen,” said Jessica Lippincott, a paleontologist with the Wyoming Dinosaurium Project.
“It goes to show that we are still finding new species of fossils all the time, and people who rockhound or collect invertebrate fossils can also contribute to science.”
“The find is incredibly rare, which might be due to some ecological adaptations to the environment at the time. Perhaps its rarity is a result of narrow specialization,” said Dr. Dean Lomax, an honorary research fellow at the University of Manchester.
The team’s paper was published in the journal Papers in Palaeontology.
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Alexey P. Ippolitov et al. 2026. ‘The big chunky belemnite’: a new relict megateuthidid from the Oxfordian (Late Jurassic) of Wyoming, USA, and its place in the evolutionary history of the group. Papers in Palaeontology 12 (5): e70123; doi: 10.1002/spp2.70123
