【化石】アルゼンチンで見つかった未知の巨大恐竜の化石

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.