Name: Secernosaurus ‭(‬Severed lizard‭)‬.
Phonetic: Seh-ser-noe-sore-us.
Named By: Michael K.‭ ‬Brett-Surman‭ ‬-‭ ‬1979.
Synonyms: Kritosaurus australis.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Ornithischia,‭ ‬Ornithopoda,‭ ‬Iguanodontia,‭ ‬Hadrosauroidea,‭ ‬Hadrosauridae,‭ ‬Saurolophinae.
Species: S.‭ ‬koerneri‭ (‬type‭)‬.
Diet: Herbivore.
Size: Holotype roughly estimated to be around‭ ‬3‭ ‬meters long. Further remains once attributed to Kritosaurus australis suggest a much larger size beween 7.5-9 meters long
Known locations: Argentina.
Time period: Late Campanian to Early Maastrichtian of the Cretaceous.
Fossil representation: Few individuals,‭ ‬but usually incomplete.

       At around three meters long,‭ ‬Secernosaurus was very small for a hadrosaur,‭ ‬though its claim to fame is not size,‭ ‬but the fact that it was the first hadrosaur known to come from South America.‭ ‬In addition Secernosaurus seems to represent a saurolophine hadrosaurid similar to Kritosaurus,‭ ‬and saurolophines are best documented in North American and Asian fossil deposits.‭ ‬This caused some confusion to palaeontologists because South America was‭ (‬and still is by some‭) ‬believed to have been completely isolated during the late Cretaceous period.‭
       An idea to explain the presence of hadrosaurids in South America during the end of the Cretaceous is that there might possibly have been a brief connection,‭ ‬or possibly some other event that allowed a brief exchange of fauna between North and South America.‭ ‬This is of course assuming that hadrosauroid dinosaurs did not cross in from Africa earlier on in the Cretaceous in a manner that may also explain the presence of spinosaurid dinosaurs in both Africa and South America.‭ ‬Unfortunately most of all we have at this time is theories based around the occurrences of fossils that do not yet show a clear transition or pattern of movement to explain the spread of hadrosaurids in South America at the end of the Cretaceous.‭ ‬But,‭ ‬now that palaeontologists know about something else that they should be looking for,‭ ‬it might only be a matter of time before a clearer picture can be established.
       A species of Kritosaurus once discovered in South America and named as K.‭ ‬australis is now commonly classified as being further examples of Secernosaurus. This additional material suggests that Secernosaurus may have been substantially larger than the three meters indicated for the holotype.‭ ‬While Secernosaurus was the first genus of hadrosaurid dinosaur to be named from South America,‭ ‬another genus called Willinakaqe was established in‭ ‬2010.‭ ‬Additionally this genus is considered to be similar to Secernosaurus,‭ ‬though is around three times the size going by currently available fossils evidence.

Further reading
- Phylogeny and palaeobiogeography of hadrosaurian dinosaurs,‭ ‬Michael K.‭ ‬Brett-Surman‭ ‬-‭ ‬1979.

- A re–evaluation of Secernosaurus koerneri and Kritosaurus australis‭ (‬Dinosauria,‭ ‬Hadrosauridae‭) ‬from the Late Cretaceous of Argentina,‭ ‬Alberto Prieto–Marquez and Guillermo C Salinas‭ ‬-‭ ‬2010.


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