A new iguanodontian dinosaur from the Khok Kruat Formation (Early Cretaceous, Aptian) of northeastern Thailand

Abstract

A new taxon of ornithopod dinosaur is described as Siamodon nimngami nov. gen, nov. sep., on the basis of a well-preserved maxilla from the Khok Kruat Formation (Aptian) of northeastern Thailand. An isolated tooth and a braincase are referred to this taxon, and the status of other ornithopod specimens from Thailand and Laos is discussed. S. nimngami nov. gen, nov. sep. is considered as an advanced iguanodontian, apparently close to Probactrosaurus, from which it differs by various characters of the maxilla. Siamodon is an addition to the already long list of advanced iguanodontian taxa from the late Early Cretaceous of Asia. The diversity and abundance of these forms may suggest that advanced iguanodontians first appeared in Asia, before spreading to other parts of the world.