Research press release


Scientific Reports

Fossils: A new giant dinosaur from Argentina



今回、Kenneth Lacovaraたちが新たに発掘した化石標本は、Dreadnoughtus schraniと命名され、完全な骨格を構成すると予想される骨の約45.3%が保存されており、全ての主要な骨格領域が残っていた。この骨格化石は、巨大なD. schraniの姿を詳しく解明する上で役立っており、D. schraniは、木釘のような歯、厚板のような肋骨、そして、ティタノサウルス類の他のほとんどの恐竜よりも大きな脚を持っていたと考えられている。上腕骨(前肢)と大腿骨(腿)の化石は保存状態が良好で、D. schraniの体重を計算するために用いられた。Lacovaraたちは、このD. schraniの推定体重が約59.3トンであるにもかかわらず、死亡当時も成長を続けていた点を指摘している。以上の新知見は、ティタノサウルス類恐竜の解剖学的構造と進化史についての新たな手掛かりとなると考えられている。

A new species of dinosaur unearthed in Southern Patagonia, Argentina, may represent one of the most complete examples of gigantic titanosaurian sauropod dinosaurs ever discovered. The colossal creature, described in Scientific Reports, may have weighed around 59.3 metric tonnes, and was approximately 26 metres long (just over one length of a standard 25-metre swimming pool). The discovery may help us to learn more about these enormous animals.

Titanosaurian sauropod dinosaurs were large-bodied herbivores that were abundant in the southern continents around 66-100 million years ago (during the Late Cretaceous period); the group includes some the most massive creatures ever to walk the Earth. However, nearly all of these giant titanosaurs are known only from very incomplete fossils, which has hindered our understanding of their anatomy as the shape and dimensions of their bodies are based on estimates from a limited sample of bones.

The new specimen uncovered by Kenneth Lacovara and colleagues, named Dreadnoughtus schrani, consists approximately 45.3% of the bones expected in a complete skeleton, representing all major skeletal regions. The preserved skeleton helps to paint a detailed picture of this giant dinosaur, which had peg-like teeth, plank-like ribs, and legs larger than most other titanosaurs. Both the humerus (forelimb) and femur (thigh) are well-preserved, and are used to calculate the creature’s mass. The authors note that despite its estimated mass of about 59.3 metric tonnes, features of the Dreadnoughtus bones indicate that it was still growing at the time of death. Together, the findings may shed more light on the anatomy and evolutionary history of titanosaurian dinosaurs.

doi: 10.1038/srep06196

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