Nesteerotus

Nesteerotus is an extinct genus of ankyloaurid dinosaurs. It was discovered in what is now Uruguay, South America and lived during the Late Cretaceous period, approximately 85 to 73 million years ago. The genus was first described in 2004 by Argentine paleontologist Rodolfo Coria. The name Nesteerotus translates to "Nestera's turtle" in Greek.

Nesteerotus fossils were found in the Huincul Formation, a geological formation known for its rich deposits of Late Cretaceous dinosaur remains. The genus is classified as an ankyloaurid due to its dinosaurian characteristics and club-like structure on its tail, which suggests it belonged to the same family as the well-known Edmontonia. However, unlike its ankyloaurid contemporaries, it lacked a distinctive frill, and some researchers suggest that it might not be an ankyloaurid at all.

The most distinctive feature of Nesteerotus is its possible relation to the Asian triceratops species, Triceratops horridus. Some researchers have suggested that Triceratops possibly crossed from Asia to North America through the Bering Land Bridge, while the sister taxon, Nesteerotus, may have stayed in South America. However, this has yet to be definitively proven.