Тайландын зүүн хойд нутгаас олдсон нэг ширхэг сээр нурууны яс нь “Mamenchisaurid” овгийн үлэг гүрвэл Ази тивийн өргөн уудам нутагт тархаж байсныг батлах чухал нотолгоо боллоо.
Тайландын Фу Крадунг (Phu Kradung) тогтоцын Фу Ной (Phu Noi) хэмээх газраас олдсон энэхүү үлэг гүрвэлийг Uragasaurus kalasinensis хэмээн нэрлэжээ. Одоогоос 150-145 сая жилийн өмнө буюу Юрийн галавын сүүлч үед амьдарч байсан энэ амьтан нь Тайландын нутаг дэвсгэрээс албан ёсоор нэрлэгдсэн анхны “Mamenchisaurid” овгийн төлөөлөгч юм.
Судлаачид PRC 460 гэж бүртгэгдсэн, сайн хадгалагдсан ганцхан сээр нурууны ясанд үндэслэн шинэ зүйлийг тодорхойлсон байна. Хэдийгээр тус олдворын ойролцоогоос бусад яснууд олдсон ч тэдгээрийг нэг амьтанд хамааралтай гэж батлах боломжгүй байжээ. Гэсэн хэдий ч уг яс нь өмнө нь олдож байгаагүй өвөрмөц шинж чанаруудыг агуулж байсан нь шинэ зүйл болохыг тогтооход хангалттай байв.
Шинжлэх ухааны хувьд энэхүү нээлт нь “Mamenchisaurid” овгийн үлэг гүрвэлүүд Зүүн Өмнөд Азийн эх газраар тархсан байсныг гэрчилж байна. Эдгээр аварга биетэн нь хүзүүний сээр нуруундаа агаараар дүүрсэн хөндийтэй байдгаараа онцлог бөгөөд тэдний хувьслын түүх болон газар зүйн тархалтыг судлахад уг олдвор чухал ач холбогдолтой юм.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
A single fossil from northeastern Thailand has led scientists to identify a brand-new species of long-necked dinosaur. Called Uragasaurus kalasinensis, the giant plant-eater is the first officially named mamenchisaurid from Thailand and adds fresh evidence that these dinosaurs lived across a larger part of Asia than the fossil record once suggested.
The species lived between 150 and 145 million years ago during the latest Jurassic. The discovery, published in Scientific Reports, adds mainland Southeast Asia to the known range of a dinosaur family that has been found mostly in China.
Mamenchisaurids are famous for their incredibly long necks. While the family is well represented in Chinese fossil sites, confirmed discoveries elsewhere have been few and far between. That makes every new find especially valuable, even when only part of the skeleton has survived.
The fossil was uncovered at the Phu Noi site in Thailand’s Phu Kradung Formation, a series of ancient river deposits that has already produced one of Southeast Asia’s richest collections of Jurassic vertebrate fossils.
One Bone was Enough to Spot a New Dinosaur
Unlike many dinosaur discoveries, Uragasaurus kalasinensis wasn’t identified from a nearly complete skeleton. Instead, the new species is based on a single, well-preserved vertebra from the front of the animal’s back, just behind its neck.
The fossil, catalogued as PRC 460, was found alongside several other sauropod bones. The researchers say those fragments couldn’t be confidently matched to the same animal, leaving the vertebra as the only bone used to describe the species.
Even so, it preserved enough distinctive features for the team to recognize that it belonged to a dinosaur no one had identified before.
Meet East Asia’s Giant Sauropod
The study describes mamenchisaurids as the dominant non-neosauropodan eusauropods across East Asia during the Middle and Late Jurassic. They stood out because of their extremely elongated neck vertebrae, which contained extensive air-filled cavities. The team also point out that more advanced members of the family developed distinctive vertebrae near the front of the tail.
“These features, although convergently evolved in several Cretaceous neosauropod lineages — including Euhelopodidae, Somphospondyli, and Titanosauria — have complicated interpretations of mamenchisaurid relationships and contributed to ongoing uncertainty regarding their phylogenetic position among sauropods.”
Those shared traits have made it harder for paleontologists to untangle exactly how mamenchisaurids fit into the sauropod family tree, the paper explain.
New Fossil Helps Map the Jurassic
The team’s analysis places Uragasaurus kalasinensis near the base of the mamenchisaurid family tree, suggesting it belongs to one of the group’s earlier branches.
The researchers say the discovery expands the family’s known range into mainland Southeast Asia and provides more evidence that mamenchisaurids were widespread across eastern Asia during the Late Jurassic. Closely related species found in China also hint at faunal connections across the region.
The paper also notes that comparisons with more distant sauropods reveal complex paleobiogeographic patterns around the Jurassic-Cretaceous transition. At the same time, the fossil record is still too limited to trace exactly how these giant dinosaurs spread across the region. The authors add that:
“Continued discoveries from the Phu Kradung Formation and other Jurassic deposits in Southeast Asia may therefore provide important insights into the early evolutionary history and biogeographic dispersal of mamenchisaurid sauropods.”
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