Олон улсын эрдэмтдийн баг АНУ-ын Вайоминг мужаас олдсон 160 сая жилийн настай, өвөрмөц бүтэцтэй олдворыг судалж шинэ төрөл зүйл болохыг тогтоожээ.
Вайоминг мужийн “Sundance Formation” хэмээх бүс нутгаас олдсон энэхүү амьтныг Wyoteuthis linsterorum хэмээн нэрлэсэн бөгөөд энэ нь одоогоор олдсон хамгийн бүдүүн биетэй белемнит юм. Белемнит нь орчин үеийн наймаалж, хавч хэлбэртний төрөл садан, далайд амьдарч байсан устаж үгүй болсон бүлэг амьтад юм. Ихэвчлэн 5-10 см урт, 1-2 см өргөн хэмжээтэй байдаг бусад белемнитээс ялгаатай нь энэхүү олдвор нь 10 см урт, 6 см өргөн хэмжээтэй байгаа нь судлаачдын анхаарлыдыг ихэд татжээ.
Олдворын түүх 1990-ээд оны сүүл үеэс эхлэлтэй бөгөөд Вайомингийн Үлэг гүрвэлийн төвийг үндэслэгч, доктор Буркхард Пол анх ер бусын том хэмжээтэй олдворыг олж байв. 2019 онд дахин нэг ижил төрлийн олдвор олдсоноор эрдэмтэд хоёр олдворыг харьцуулан судалж, шинэ төрөл зүйл болохыг албан ёсоор баталгаажуулсан байна. Судалгааны баг компьютер томограф (CT) ашиглан олдворын дотоод бүтцийг гэмтээлгүйгээр шинжилсэн бөгөөд энэ нь эртний белемнитүүдийн хувьслын холбоог илүү тодорхой болгожээ.
Палеонтологичдын үзэж буйгаар, уг амьтны биеийн харьцангуй том хэмжээ нь тухайн үед амьдарч байсан бусад жижиг белемнитүүдийг агнах давуу талыг олгодог байсан байж магадгүй. Одоогоор энэ төрөл зүйлийн ердөө хоёр л олдвор олдоод байгаа нь тухайн үеийн орчиндоо тусгайлан дасан зохицсон амьдралын хэв маягтай байсантай холбоотой байж болох талтай гэж судлаачид тайлбарлаж байна. Энэхүү нээлтийн дэлгэрэнгүйг “Papers in Palaeontology” сэтгүүлд нийтэлжээ.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
Researchers have described Wyoteuthis linsterorum, a Jurassic creature that lived roughly 160 million years ago and holds the title of the “fattest” belemnite ever found. Only two fossils of it are known, and both came out of Wyoming.
Belemnites belonged to an extinct group of marine animals related to modern squid and octopuses. They are among the most frequently discovered fossils in the world, which makes a find this strange all the more notable. An international team from the United States, the United Kingdom and New Zealand detailed the discovery in the journal Papers in Palaeontology.
Wyoming’s Sundance Formation preserves an ancient inland sea that once stretched across much of the western United States. It has yielded millions of belemnite fossils, so the region is hardly short on material to study.
A Rostrum Unlike Any Other
Belemnites are best known for their bullet-shaped internal skeletal structures, called rostra or guards, which are often the only parts of the animal to survive in the fossil record. In Wyoming, they are commonly nicknamed “squid butts,” according to paleontologist and study co-author Jessica Lippincott.
Most Wyoming specimens measure between 5 and 10 centimeters in length and just 1 to 2 centimeters across. The new species is a different beast entirely: its rostrum is about 10 centimeters long but reaches 6 centimeters in width, making it the thickest of its kind on record. The living animal, arms included, could have reached around 60 centimeters, or about two feet.
Paleontologist Bill Wahl, who has devoted much of his career to searching for fossils across the state, recognized that the specimen deserved a closer look. He said the belemnite “stuck out like a sore thumb” compared with the countless others found in the region. Lippincott had encountered countless Pachyteuthis belemnites over the years, but this particular specimen left her stunned. It was “unlike anything I have ever seen!“
Nearly Three Decades in the Making
Although the species has only now been formally described, its story begins in the late 1990s. Dr. Burkhard Pohl, founder of the Wyoming Dinosaur Center, noticed a belemnite considerably larger than any he had previously encountered. Despite its unusual appearance, it then sat unstudied in a museum collection drawer for many years.
A second specimen surfaced when fossil collector Cliff Linster found one near Ten Sleep, Wyoming, and donated it to the Wyoming Dinosaur Center in 2019. With two fossils to compare, scientists finally had enough evidence to recognize an entirely new species. The genus name Wyoteuthis means “a squid from Wyoming,” while linsterorum recognizes Linster and his family.
Linster died in June, before the research was published, though he knew scientists were investigating his discovery and was enthusiastic about it. Dr. Dean Lomax, an Honorary Research Fellow at The University of Manchester, first worked with Cliff and his wife, Sandy, in 2009, during a week-long dinosaur bonebed dig in northern Montana. He called the naming “bittersweet,” but said:
“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.”
Clues to a Hidden Evolutionary Link
During the study, the team used computed tomography (CT) scanning to examine the fossils‘ internal structures without damaging them. The scans revealed an unexpected connection to an ancient belemnite family that scientists had believed disappeared millions of years before this animal lived.
Alexey Ippolitov, a belemnite expert and PhD student now at Victoria University of Wellington in New Zealand, said he was “deeply surprised” by the specimen, particularly since belemnites have been studied for more than 200 years. He suggested that:
“A possible explanation is that their relatively large size gave them an advantage when hunting co-occurring smaller belemnites of the genus Pachyteuthis. 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.”
Why is the species so hard to find? Lomax describes the discovery as “incredibly rare” and links this to possible ecological adaptations to the environment of the time, adding that narrow specialization may be the explanation.
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