Secernosaurus, meaning "severed lizard," was a herbivorous dinosaur belonging to the hadrosaur family, commonly referred to as "duck-billed" dinosaurs. These remarkable creatures thrived during the Late Cretaceous period.

What sets Secernosaurus apart from its relatives is its geographical presence in South America. While most hadrosaurs inhabited the Laurasian continents of Eurasia and North America, Secernosaurus and its close kin established their homes in South America. It's believed that the ancestors of Secernosaurus made their way into South America during the Late Cretaceous, capitalizing on a temporary land bridge that connected North and South America. This bridge facilitated the exchange of various life forms between these two continents.

Regarding its size, Secernosaurus may have been relatively small for a hadrosaurid. However, pinning down its exact dimensions proves challenging because the holotype specimen was not fully matured.

Secernosaurus flourished in what we now recognize as Patagonia during the Maastrichtian age of the Cretaceous period. Notably, it was among the limited number of hadrosaurs that inhabited South America. The presence of these creatures in this region likely signifies a migration from North America, possibly occurring during the Campanian period when the proto-Antilles could have acted as an island chain, enabling terrestrial vertebrates to traverse between these two continents. This migration might have influenced the decline of the indigenous ornithopods, the elasmarians.