Ratchasimasaurus belongs to the family of non-hadrosaurid iguanodontian ornithopod dinosaur. It lived during the Aptian age of early Cretaceous period. The fossil remains of the species were first discovered in Thailand, Nakhon Ratchasima Province - Khok Kruat Formation. The dinosaur is of a herbivore type and comes under the classification of Chordata, Reptilia, Dinosauria, Ornithischia, Ornithopoda, Igaunodontia.
The species was named by Masateru Shibata, Pratueng Jintasakul & Yoichi Azuma in 2011. A very little is known about this dinosaur as Dentary (lower jaw) is the only found fossil representation. This dentary is used to further establish the genus and found it shares both primitive and derived characters with that of Igaunodon dinosaur group. The skeletal structure, length and weight of Ratchasimasaurus still remain unpredicted due to the incomplete remains.