Эрдэмтэд 105 сая жилийн өмнө амьдарч байсан, ургамал идэшт үлэг гүрвэлийн хамгийн өвөрмөц төрөл зүйл болох Nigersaurus taqueti-ийн хооллох тогтолцоог судлан тогтоожээ.
Бүгд Найрамдах Нигер Улсын нутгаас олдсон энэхүү үлэг гүрвэлийн үлдэгдлийг палеонтологич Филипп Таке 1965-1972 оны хооронд анх илрүүлсэн бол 1997 оноос Пол Сереногоор ахлуулсан баг нарийвчилсан малтлага явуулж, 1999 онд шинжлэх ухаанд албан ёсоор бүртгэжээ. Ойролцоогоор 30 фут урт, хоёр тонн жинтэй уг үлэг гүрвэлийн яс нь шувууныхтай адил агаарын уут бүхий хөндийтэй тул маш хөнгөн бүтэцтэй байв. Түүний гавлын ясны зарим хэсэг нь маш нимгэн, гэрэл нэвтрүүлдэг байсан нь судлаачдын анхаарлыг татсан байна.
Nigersaurus-ийн хамгийн содон шинж нь түүний шүдний бүтэц бөгөөд нийт 500 орчим идэвхтэй шүдтэй байжээ. Шүдний чулуужсан олдворт хийсэн микроскопийн шинжилгээгээр тус амьтан шүдээ 14 хоног тутамд шинэчилдэг байсныг тогтоов. Уг үлэг гүрвэл нь хоолоо зажлах бус харин хайч мэт шүдээрээ тасдан идэхэд зориулагдсан өргөн, дөрвөлжин хоншоортой байсан бөгөөд газрын ойролцоох элсэрхэг, хатуу ургамлаас үүдэн шүд нь байнга элэгддэг байсан нь ийм хурдан нөхөн төлжилтийг шаардаж байжээ.
2007 онд профессор Жефф Вилсон Мантилла болон түүний баг орчин үеийн компьютер томографын (CT) технологийг ашиглан олдворын гавлын ясыг бүрэн бүтнээр нь сэргээн босгосон байна. Энэхүү дижитал загварчлалаар дамжуулан үлэг гүрвэл нь хоншоороо байнга газар луу чиглүүлэн бэлчээрлэдэг байсан нь тогтоогджээ. Энэхүү нээлт нь эртний аварга амьтдын анатоми болон хооллох зуршлыг орчин үеийн дүрслэх техникээр танин мэдэхэд чухал ач холбогдолтой болсон юм.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
A dinosaur with around 500 working teeth and the ability to replace each one every 14 days remains one of the most unusual herbivores ever identified. Nigersaurus taqueti, which lived about 105 million years ago in what is now the Republic of Niger, evolved a feeding system unlike that of any other known dinosaur.
Its lightweight skeleton, delicate skull, and remarkable dental adaptations have fascinated paleontologists since the species was formally described in 1999. Decades of research have also revealed how modern imaging techniques helped reconstruct an animal unlike any previously discovered.
The story of Nigersaurus began in the deserts of Niger, where French paleontologist Philippe Taquet conducted expeditions between 1965 and 1972. Among the many fossils collected were the remains of an unidentified sauropod, though they were not examined in detail at the time because of the sheer number of discoveries.
The mystery was revisited in 1997 when a team led by paleontologist and National Geographic Explorer Paul Sereno returned to the Gadofaoua fossil site. The excavation yielded additional fossil material, allowing the team to formally describe the new dinosaur in 1999 as Nigersaurus taqueti, a name honouring both its country of origin and Philippe Taquet.
An Unusually Delicate Giant
Although Nigersaurus measured about 30 feet long and weighed roughly two tons, its skeleton was surprisingly light. Researchers recovered numerous bones, including articulated neck vertebrae and several skull elements belonging to different individuals, revealing a body unlike that of other large sauropods. Professor Jeff Wilson Mantilla said that:
“The skull bones were so strange looking that it was challenging to identify which element we were looking at.”
Some were exceptionally thin, with light able to pass through them. Those fragile fossils demanded careful excavation and preparation before scientists could understand how the skull was assembled.
The research team also found that air sacs extended into several bones, much like those seen in modern birds. These structures helped reduce the dinosaur’s weight while maintaining skeletal support.
A Mouth Designed for Nonstop Grazing
The feature that made Nigersaurus famous was its extraordinary dental system. At any given time, the dinosaur carried around 500 active teeth, with replacement teeth continuously developing beneath them.
In a study published in PLOS One, researchers determined how quickly Nigersaurus replaced its teeth by examining microscopic growth lines preserved in fossilized teeth. Mantilla explained that counting those daily lines showed each tooth was replaced approximately every 14 days. Behind every exposed tooth, as many as seven replacements were already forming.
Paul Sereno told National Geographic that the dinosaur’s mouth appeared designed for “nipping rather than chomping or chewing.” Its broad, square muzzle resembled the feeding adaptations of modern grazing animals, while wear patterns showed the teeth slid past one another like a pair of shears rather than crushing food.
The dinosaur’s diet helps explain this remarkable replacement rate. Low-growing plants such as horsetails contain silica, and vegetation close to the ground often carries sand and grit. Researchers found that these abrasive materials would have worn down the teeth rapidly.
CT Scans Reveal the Dinosaur’s Head Position
No complete skeleton has ever been discovered, leaving paleontologists to reconstruct the animal using fossils from multiple individuals. Advances in medical imaging made that task possible.
In 2007, Mantilla and his colleagues digitally scanned the available skull bones using CT technology before adjusting them to the same scale to create a complete reconstruction. National Geographic notes that this was one of the earliest examples of CT scans being used to rebuild the skull anatomy of a dinosaur.
According to the Digimorph Lab at the University of Texas at Austin, the scans revealed hidden details inside the fossils. Researchers found that Nigersaurus naturally held its muzzle pointed toward the ground, matching its grazing lifestyle. The digital reconstruction also suggested the herbivore relied little on its sense of smell while feeding.
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