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Secernosaurus was a member of a small group of hadrosaurs native to South America: the Austrokritosaurs, and it was the first of this group to be formally named. Most hadrosaurs lived in Laurasia (what is now North America and Eurasia) which was seperated from South America in the Cretaceous. The existence of Secernosaurus and its relatives suggests a land bridge temporarily formed between North and South America at this time, allowing North American kritosaurines to migrate South.
So far, only one specimen of Secernosaurus has been found. This fossil was previously thought to belong to a subadult, but recent study shows it was likely mature, or at least almost mature. This makes it the smallest of the Austrokritosaurs, only 4–5 metres (13–16 ft) long. Still a large animal, but rather small by hadrosaur standards!
Secernosaurus received its big screen debut in Prehistoric Planet’s second episode, however, the design of the animals were based off the better known Huallasaurus australis, as Huallasaurus was thought to be a species of Secernosaurus at the time.
Secernosaurus koerneri lived in the Late Cretaceous Lago Colhué Huapí Formation In Argentina. As depicted in Prehistoric Planet, this environment was semi-arid with large deposits of gypsum, and fluctuated between seasonally wet conditions and intense aridization. But Secernosaurus wasn’t the only dinosaur in this environment. It shared the formation with titanosaurs like Elaltitan lilloi, Argyrosaurus superbus, and Aeolosaurus rionegrinus. Fragmentary remains of dromaeosaurids and megaraptorids have been found here, as well as the ornithischians Notoceratops (which could have been either a ceratopsian or another hadrosaur) and Sektensaurus (a possible elasmarian). Turtles, pseudosuchians, and lungfish have also been found, which would have made use of the floodplains during the wet season and possibly aestivated during the dry.