Plesiohadros

Phylogeny: Dinosauria > Ornithischia > Genasauria > Neornithischia > Cerapoda > Ornithopoda > Iguanodontia > Ankylopollexia > Styracosterna > Hadrosauriformes > Hadrosauroidea

Overview: Fossils now referred to the genus Plesiohadros were discovered sometime between the 1960’s and 1970’s, in the Gobi Desert of Mongolia, by a team of Polish and Mongolian researchers. Recovered fossils would consist of some skull material, limb bones, vertebrae, and other pieces of its overall skeleton. The bones would remain without a formal description for decades, until they were properly studied in the 2010’s. In 2014, the genus and species Plesiohadros djadokhtaensis was announced to the world in a formal publication. The generic name of Plesiohadros translates as “near to hadrosaurs”, referring to how it had many traits in common with the true hadrosaurids, or “duck-billed” dinosaurs. Indeed, among the non-hadrosaurid hadrosauroids, Plesiohadros was one of the most closely related to the Hadrosauridae. It retained some more basal traits, which is why it wasn’t a proper hadrosaurid. It’s a kind of “missing link” between them and more basal taxa.

Plesiohadros was similar in appearance to most other hadrosauroids, being a fairly sturdy dinosaur that could walk both bipedally and quadrupedally. It possessed a keratinous beak at the front of its jaws, set in front of tightly-packed teeth. Lower-level vegetation may’ve made up most of its diet. It differed from other hadrosauroids in a few details. The bone around its eye sockets was notably rougher than what we usually see, while its ankle anatomy was a little bit unusual as well. While it wasn’t a true hadrosaurid, it did have “advanced” teeth rows like such dinosaurs. As the name of its type species implies, Plesiohadros was at first thought to be from the Djadochta Formation, but it’s now known to have come from the Alagteeg Formation, just below the Djadochta. This preserves a somewhat arid environment. Plesiohadros probably coexisted with the sauropod Abdarainurus, but also possibly a number of ankylosaurs, basal ceratopsians, and dromaeosaurids.