Kelumapusaura

Phylogeny: Dinosauria > Ornithischia > Genasauria > Neornithischia > Cerapoda > Ornithopoda > Iguanodontia > Ankylopollexia > Styracosterna > Hadrosauriformes > Hadrosauroidea > Hadrosauridae > Saurolophinae > Austrokritosauria

Overview: Hadrosaurid dinosaurs, the true “duck-bills”, were once thought to be a lineage unique to the northern hemisphere, primarily to North America and Asia. Discoveries in recent decades have proven this to be a false assumption. Kelumapusaura is an example of a southern hadrosaur, its fossils being known from the Allen Formation of Argentina. It would’ve lived around seventy million years ago, possibly alongside other dinosaurs like Austroraptor and a myriad of other prehistoric animals. Described as a genus in 2022, Kelumapusaura takes part of its name from the language of the local Mapuche people, combined with Greek, meaning “red earth lizard”. This was chosen in reference to the reddish sediments from which its remains were excavated. Fossils of some other hadrosaurs are also known from the Allen Formation.

Kelumapusaura was a decently large hadrosaur, measuring between eight and nine meters long. It’s probably the largest hadrosaur known from the Allen Formation. Like other hadrosaurs, it would’ve spent most of its time down on all fours as it grazed for food, but it retained the ability to rear up on its hind limbs to feed from tree branches or survey its surroundings. Most southern hadrosaurid dinosaurs are classified within a clade called the Austrokritosauria, which appears to have been the case with Kelumapusaura. The name of this group invokes that of North America’s Kritosaurus. The austrokritosaurs, like Kritosaurus, often had high-arched nasal bones, which may’ve supported some kind of display structure in life, or possibly air sacs. Austrokritosaurs may’ve been close relatives of Kritosaurus itself, which belonged to the hadrosaur tribe Kritosaurini.