[3] The holotype of Secernosaurus koerneri is FMNH P13423,[1] a partial skeleton from the Lago Colhué Huapi Formation of Chubut province, Argentina.

[4] In 2010, Albert Prieto-Marquez and Guillermo Salinas argued that Kritosaurus australis was synonymous with Secernosaurus koeneri.

[5] Phylogenetic analyses have found Secernosaurus to be a member of the hadrosaurid tribe Kritosaurini within the subfamily Saurolophinae.

[1] Rozadilla et al. (2022) recovered all South American saurolophines to group together within a single clade consisting of Secernosaurus, Huallasaurus, Kelumapusaura, and Bonapartesaurus.

The results of their phylogenetic analyses of Saurolophinae are displayed in the cladogram below:[7] Wulagasaurus Acristavus Maiasaura Probrachylophosaurus Brachylophosaurus Secernosaurus Bonapartesaurus Kelumapusaura Huallasaurus Kritosaurus Rhinorex Gryposaurus latidens Gryposaurus notabilis Gryposaurus monumentensis Kamuysaurus Prosaurolophus Saurolophus osborni Saurolophus angustirostris Laiyangosaurus Kerberosaurus Shantungosaurus Edmontosaurus annectens The geologic layers of the Lago Colhué Huapi Formation, where Scernosaurus hails from, have proved difficult to interpret historically, their assignment shifting around between several different geologic formations before finally being settled as its own unit of the Chubut Group, dating to the Maastrichtian.

However, palynological data indicates that during the upper deposits of the formation at the very end of the Cretaceous and into the Danian age of the Paleocene, the climate become more mild once again and returned to a balanced wet and dry season.

Very fragmentary remains of dromaeosaurid and megaraptoran theropods have also been discovered, as is expected from other formations from a similar time and place.

The enigmatic ornithischian dinosaur Notoceratops, based on a lost fragmentary specimen originally considered to belong to a ceratopsian but now debated between that identity and that of a hadrosaur.