Шинжлэх ухааны баг 2011 онд илрүүлсэн үлэг гүрвэлийн гавлын ясны бүтцийг судалсны дүнд түүний эрүүний хөдөлгөөн нь тоть шувуутай төстэй болохыг тогтоожээ.
Монтаны Гарфилд дүүргийн Хелл Крик тогтоцоос 2011 оны долдугаар сард олдсон, ойролцоогоор 12 кг жинтэй, шүдгүй, хошуутай энэхүү үлэг гүрвэлийг Infernogallus jamesi буюу “тамын тахиа” хэмээн нэрлэжээ. Stony Brook их сургуулийн судлаач Грегори Ф.Фунстон болон Рояал Онтарио музейн Дэвид К.Эванс нарын удирдсан баг уг амьтны хүзүүтэйгээ хадгалагдсан гавлын ясыг шинжилсэн байна. Энэ нь caenagnathids бүлгийн үлэг гүрвэлүүдээс олдож буй анхны бүрэн бүтэн гавлын яс бөгөөд уг бүлэг нь өд сөдтэй, шүдгүй хошуутай, хөндий ястай шувуу төст үлэг гүрвэлүүд юм.
Ясны өсөлтийн цагиргийг шинжлэхэд уг амьтан 6-7 орчим настай, бүрэн өсөж гүйцсэн болох нь тогтоогджээ. Судлаачид гавлын ясны сканнерын тусламжтайгаар доод эрүүг урагш хойш хөдөлгөх боломжийг олгодог үе болон булчингийн бүтцийг сэргээн босгосон байна. Эрүү нь 15 мм хүртэл хэмжээгээр гулсах чадвартай бөгөөд тагнай болон доод эрүүний ховил, сэртэнүүд нь хоорондоо шүтэлцэн зөөлөн хоол хүнсийг няцлах, нунтаглах үүрэг гүйцэтгэдэг байсныг таамаглаж байна.
Ходоодны чулуу илрээгүй нь энэ амьтныг ургамал идэштэн байсан ч хатуу навч бус, тотьны нэгэн адил зөөлөн жимсний зөөлөн эдийг идэхэд мэргэшсэн байж болзошгүйг харуулж байна. Гэсэн хэдий ч олдворын дэргэдээс жимс, үр, эсвэл ходоодны агууламж олдоогүй тул энэ нь зөвхөн яс болон булчингийн бүтцэд үндэслэсэн таамаглал юм. Nature Communications сэтгүүлд нийтлэгдсэн уг судалгааны тоймд статистик шинжилгээний хүрэлцээ болон хоол тэжээлийн талаарх дүгнэлтийн талаар эрдэмтдийн дунд харилцан адилгүй байр суурьтай байсан нь тэмдэглэгджээ.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
A toothless dinosaur unearthed in Montana has been named Infernogallus jamesi, roughly “hell chicken.” A new study in Nature Communications argues that its jaw slid back and forth to mash soft fruit, much as a parrot’s does.
The animal was dug up in July 2011 in the Hell Creek Formation of Garfield County. It weighed around 26 pounds (12 kilograms) and had a beak instead of teeth. Gregory F. Funston of Stony Brook University’s Department of Anatomical Sciences led the work, and David C. Evans of the Royal Ontario Museum in Toronto is the other corresponding author.
The skull is still attached to the neck, and the paper calls it “the first intact cranium known for the group.” That group, the caenagnathids, has mostly been known from scraps. Funston, Kyle Atkins-Weltman and Eric Snively described them in a 2024 blog post as “a group of bird-like dinosaurs with feathers, toothless beaks, and hollow bones.”
A Grown Animal with a Sliding Jaw
This was no juvenile. The 2024 blog post explains that “as bone grows, it lays down marks each year, like tree rings, so looking at these slides we could see how old this animal was, and how fast it was growing.” For Infernogallus, the rings say at least 6 years old, probably 7, and done growing.
Working from scans of the crushed skull, the team rebuilt big palate muscles that pulled the lower jaw forward and back. They also found a joint that let it slide up to 15 millimeters (about 0.6 inch), and ridges and grooves on the palate and lower jaw met as it moved.
That would have worked “for shearing, mashing, or crushing soft foods, similar to a mortar and pestle,” the authors write.
Why Fruit?
The researchers found no stomach stones, which plant-eaters often swallow to grind tough leaves, even though the belly ribs were all there. The best living match was the Pesquet’s parrot of New Guinea, which, according to the paper, “processes fruit by consuming the pulp and discarding the seed.” So the team proposes that:
Infernogallus “could have been specialised for processing soft fleshy fruit, although it is likely that other soft plant materials also formed a significant component of its diet.”
Their family tree places the first caenagnathids soon after flowering plants started making fruit, and in their second reply to reviewers the authors pointed to newer work “showing that fruits appropriate for caenagnathids were both more common and larger in the Late Cretaceous than previously recognized.”
Fruit flesh comes and goes with the seasons. The paper says the animal may have lived largely on sporadic or seasonal foods, just before the dinosaur-killing asteroid knocked out the plants at the bottom of the food web.
Why Scientists Aren’t Entirely Sure What This Dinosaur Ate?
Nature Communications posted the whole peer review next to the paper, and it makes lively reading. One reviewer felt the ecological conclusions were qualitative and “not supported by any statistical analyses.” The authors said they had grappled with this, since birds and dinosaurs occupy separate parts of their charts, which makes statistics hard to apply. They ran the tests anyway. In one, every dinosaur came out as an omnivore at more than 85 percent probability, except Infernogallus, at 75 percent omnivore and 25 percent soft food.
The authors admitted the stats were not robust enough for conclusions, and the reviewer eventually conceded that qualitative interpretation was the sensible approach. The tests went into the supplementary material. Not every comment was so severe. Another reviewer, after two rounds of hard questions, signed off with a remark about the dinosaur’s name:
“Lastly, I just want to say that I really love the name Infernogallus. Hell chicken is such a great name!” The authors replied that a colleague had suggested it, and the published paper thanks C. Woodruff for “suggesting the generic name.”
Still, the picture is incomplete. No fruit, seeds or stomach contents turned up with the skeleton, so the diet is reconstructed from bones and muscle maps alone.
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