Paleontologists have unearthed the remains of an immense, fast-growing dinosaur whose body proportions don’t match those predicted by the evolutionary trends that characterize its more diminutive kin.

Towering high above any of its relatives or namesakes, this caenagnathid dinosaur, unrelated to the likes of Velociraptor and Utahraptor, was a colossus of the Iren Dabasu Formation. Discovered in ...