Belemnites rank among the most abundant fossils found anywhere in the world. They are recognised by their bullet-shaped remains, known as a rostrum or guard, a dense mineralised structure that anchored the soft tissues of the living animal and is the part most often preserved. Millions of these bullet-shaped fossils have been recovered from Wyoming’s Sundance Formation, the sedimentary record of an ancient inland sea that once covered much of the western United States during the Jurassic period. Local collectors know them so well that, according to Wyoming palaeontologist and study co-author Jessica Lippincott, they are affectionately nicknamed squid butts. Most Wyoming belemnites measure around five to ten centimetres in length and only one to two centimetres across, producing the slender, dart-like profile familiar to fossil hunters everywhere.

The newly discovered species breaks that mould entirely. Its rostrum is around ten centimetres long but reaches up to six centimetres in width, giving it a broad, barrel-like silhouette unlike anything previously recorded in the group. Based on the dimensions of the preserved skeleton, researchers estimate that the living animal would have reached approximately sixty centimetres in total length, including its arms. That makes it not merely a large example of a familiar form, but a genuinely different body plan within a lineage whose fossil record is otherwise remarkably consistent. The discovery is described in the international journal Papers in Palaeontology by an international team of researchers from the United States, the United Kingdom and New Zealand, including Dr Dean Lomax, an Honorary Research Fellow at The University of Manchester.

The scientific journey behind the specimen began almost three decades ago. The first fossil was unearthed in the late 1990s by Dr Burkhard Pohl, founder of the Wyoming Dinosaur Center, who spotted a belemnite far larger than any he had encountered before. Despite its striking appearance, the fossil sat unstudied in a museum collection drawer for many years. The breakthrough came when a second specimen was discovered near Ten Sleep, Wyoming, by fossil collector Cliff Linster, who donated it to the Wyoming Dinosaur Center in 2019. Together, the two fossils provided the comparative evidence needed to confirm that the animals represented something genuinely new rather than simply unusually robust individuals of a known species, and to formally describe and name it.

The investigation was instigated by Wyoming palaeontologist and co-author Bill Wahl, who has spent much of his career searching for fossils across the state and recalled that this particular belemnite stuck out like a sore thumb. Recognising the significance of the specimens, he assembled an international team to study them, including belemnite expert Alexey Ippolitov, now based at Victoria University of Wellington in New Zealand. The team applied computed tomography, or CT scanning, to examine the fossils in fine detail without any risk of damaging them. The scans revealed internal anatomical features that proved decisive: they confirmed the animal belonged to an ancient family of belemnites previously thought to have disappeared millions of years earlier, making Wyoteuthis linsterorum a relict lineage that survived unnoticed into the Late Jurassic of North America.

For specialists who have spent their careers on this group, the find was astonishing. Ippolitov said he was deeply surprised to discover a fossil from such a well-studied group that differed so radically from anything previously known. After more than 200 years of palaeontological research on belemnites, he noted, discoveries of this magnitude are exceptionally rare. The finding underscores how much remains hidden even within heavily sampled rock units and familiar fossil groups, and it demonstrates the continuing value of museum collections, where unstudied specimens can wait decades for the right expertise and comparative material to unlock their significance.

Why this belemnite grew so thick, and why it is so rare, remain open questions, but the researchers offer a provocative ecological hypothesis. According to Ippolitov, a possible explanation is that the animal’s relatively large size gave it an advantage when hunting co-occurring smaller belemnites of the genus Pachyteuthis, the abundant slender forms that dominate Wyoming’s Jurassic deposits. Modern squid, after all, are hardly picky when it comes to prey: they readily hunt not only other species of cephalopods but sometimes even their own kind. If that interpretation is correct, Wyoteuthis linsterorum may have occupied a predatory niche within the Sundance sea, using its bulk and power to prey upon the very belemnites that swarm in the fossil record around it.

Dr Lomax, who is also an 1851 Research Fellow at the University of Bristol, has a personal connection to the story. He dug up dinosaurs alongside Cliff Linster and his wife Sandy when he was a teenager, and reflected on the honour of naming the fossil after his old friend. He recalled meeting Cliff and Sandy in 2009, when he spent a week excavating a dinosaur bonebed on their property in northern Montana, listening to Cliff share his passion for fossils, including this very belemnite. Lomax described the publication as bittersweet, since Cliff did not live to see it, but noted that the naming immortalises him and his family in the history of palaeontology. He suggested that the find’s incredible rarity might be due to ecological adaptations to the environment at the time, and that perhaps its rarity is a result of narrow specialisation, an animal so tightly tuned to a particular way of life that it left only the faintest trace.

The naming itself carries the story forward. Wyoteuthis translates as a squid from Wyoming, while the species name linsterorum honours Cliff Linster and his family. Cliff discovered one of only two known specimens of the new species and donated it for scientific study, and he knew researchers were working on his find and was excited to see it formally described before his death in June this year. The Linster family are no strangers to remarkable fossils, perhaps most famously the dinosaur Bambiraptor. Jessica Lippincott, who has spent years collecting the common Pachyteuthis belemnites of Wyoming, said this one is unlike anything she has ever seen, adding that people who rockhound or collect invertebrate fossils can also contribute to science. Both specimens are now on display at the Wyoming Dinosaur Center in Thermopolis, Wyoming, and Lomax, author of the recently published book The Secret Lives of Dinosaurs, which highlights Wyoming fossils, hopes the discovery will inspire a new generation of collectors to look more closely at the stones beneath their feet.

Subject of Research: A new species of unusually thick Late Jurassic belemnite from the Sundance Formation of Wyoming, USA

Article Title: “Peculiar” new species of Jurassic squid found in Wyoming

Article References: “Peculiar” new species of Jurassic squid found in Wyoming. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: belemnite, Jurassic, Wyoming, cephalopod, paleontology, Sundance Formation, fossil, CT scanning, new species, Wyoteuthis linsterorum, inland sea, museum collections