Эрдэмтэд 415 сая жилийн тэртээх олдвор дээр үндэслэн Praearcturus gigas нь шинжлэх ухаанд мэдэгдэж буй хамгийн том хилэн хорхой болохыг тогтоов.
Их Британид олдсон 16 см урттай хавчны хэлтэрхий нь 100 гаруй жил үргэлжилсэн маргааныг эцэслэлээ. Палеонтологийн судалгаагаар энэхүү олдвор нь Praearcturus gigas хэмээх эртний амьтанд хамаарах бөгөөд уг амьтан нэг метрээс урт биетэй байсныг тогтоосон байна. Анх 1871 онд Генри Вүүдворд үүнийг хавч хэлбэртэн гэж андуурч байсан бол 2015 онд Канадаас олдсон Eramoscorpius-ийн олдвортой харьцуулснаар түүнийг хилэн хорхой болох нь батлагджээ. Лондонгийн Байгалийн түүхийн музейн судлаач Ричи Ховардын тайлбарласнаар, олдвор дахь гурвалжин хэлбэртэй өвчүүний бүтэц нь хилэн хорхойн шинж тэмдгийг тодорхой илтгэж байна.
Девоны галавын эхэн үед хамаарах энэхүү махчин амьтан нь хуурай газрын экосистем бүрэлдэж эхлэхээс өмнөх үед амьдарч байжээ. Тухайн үед хуурай газар дээр өрсөлдөхүйц том махчин амьтан байгаагүй нь Praearcturus gigas-ыг ийнхүү аварга том биетэй болох боломжийг олгосон гэж судлаачид үзэж байна. Түүнчлэн олдворуудаас харахад энэ амьтан хуурай газар болон усан орчинд хоёуланд нь амьдардаг байсан байх магадлалтай юм.
Одоогийн хилэн хорхойнууд дунд хамгийн том нь гэгдэх Энэтхэгийн ойн хилэн хорхой ердөө 23 см хүрдэг бол Praearcturus gigas нь түүнээс дөрөв дахин том байжээ. Энэхүү нээлт нь амьтны ертөнцийн хувьсал болон эртний экосистемийн хөгжлийн талаарх шинэ ойлголтыг бидэнд өгч байна. Цаашид олдворын бүрэн бүтэн байдлыг тогтоох болон тус зүйл хэрхэн мөхсөнийг судлах ажил үргэлжлэх болно.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
A 16-centimetre pincer fossil recovered in the United Kingdom has settled a question that sat unresolved for more than a hundred years: it belongs to Praearcturus gigas, now confirmed as the largest scorpion known to science. Using the claw’s proportions, researchers calculated that the full animal stretched over a metre long, according to a study published in the journal Palaeontology.
The fossils date to 415 million years ago, during the Early Devonian period, a time when animal life had barely made it onto land. Land animals had only emerged from the oceans about 15 million years before Praearcturus was alive, and the ground itself offered little more than fungi, moss, and early plants a few inches tall. Finding a predator of this size from so early in that timeline is what has drawn researchers’ interest.
Named Twice, Misunderstood for Over a Century
When paleontologist Henry Woodward first described Praearcturus in 1871, he took it for a giant woodlouse-like crustacean rather than a scorpion, an interpretation still preserved in its name, since Arcturus refers to a group of living woodlice. The fossils available at the time were too fragmentary to say otherwise, and critically, they were missing a scorpion’s tail, the one feature that would have made the identification obvious.
Suspicion that Praearcturus was actually a scorpion first surfaced in the 1980s, but the fragments still couldn’t prove it. The case was made in 2015, when a well-preserved ancient scorpion called Eramoscorpius was described from Canada.
Dr Richie Howard, lead author of the new study and Curator of Fossil Arthropods at the Natural History Museum, London, explained that Eramoscorpius preserved a sternum, a long triangular structure with a groove down its middle, on the underside of its carapace. Praearcturus turned out to have the same structure. As Howard put it, “this shows beyond doubt that Praearcturus must be a scorpion.”
A Single Pincer Reveals the Scorpion’s True Size
Because no complete specimen of Praearcturus has ever turned up, researchers rebuilt its size from fragments. The key piece was a 16-centimetre pincer (6.3 inches), which the team compared to the claw-to-body ratios of related scorpions to estimate total length. The result put Praearcturus at over a metre long, well past the previous record holder and far beyond anything seen in scorpions today.
The living world’s largest scorpion, the Indian forest scorpion, reaches only about 23 centimetres, less than a quarter of the length reconstructed for Praearcturus. Size limits like this generally come down to habitat: aquatic and semi-aquatic arthropods can grow much larger because water supports their weight, which is why the Japanese spider crab, at nearly four metres across with its legs extended, remains the largest living arthropod while land-based species stay comparatively small.
Few Rivals Awaited It on a Nearly Empty Land
Devonian sites such as Scotland’s Rhynie Chert show a terrestrial world still limited to small plants, fungi, and tiny pioneering arthropods, without the complex food webs that would come later.
Howard notes that when people picture giant arthropods, they usually think of animals like the six-foot millipede Arthropleura or the dragonfly-like griffinflies, “but these species lived in the Carboniferous Period at least 55 million years after Praearcturus, once land-based ecosystems had time to develop.”
That gap helps explain how Praearcturus got so large so early. With no other large land predators competing for the same small arthropod prey, Howard suggests the species “might have grown so big because there weren’t any other large predators, allowing it to dominate its environment.” On land, at least, it would have faced essentially no competition for what it hunted.
Fossils Suggest a Life Split Between Land and Water
Fossils recovered in Portishead, North Somerset hint the species, or something closely related, may have survived for at least another 40 million years, though the link to Praearcturus remains tentative. Fossils from Wales add another piece to the picture: flap-like structures called epimera, similar to those on modern lobsters and crabs. Howard said, “without complex ecosystems to support Praearcturus on land, these animals probably spent part of their lives hunting in water.”
Dr Greg Edgecombe, a co-author of the study and fossil arthropod expert at the Natural History Museum, points out that DNA-based family trees place scorpions close to spiders and other arachnids that share book lungs, suggesting scorpions descend from an air-breathing ancestor.
If that holds, Praearcturus would represent an animal whose ancestors moved onto land only to return to the water, likely hunting fish and other large prey it couldn’t find on the sparse shoreline. More fossils will be needed to confirm how long the species lasted and how it eventually disappeared.
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