Siamodon is an extinct genus of iguanodontian ornithopod dinosaur from Early Cretaceous deposits of northeastern Thailand.

[1] Siamodon is known from the holotype PRC-4, a well-preserved left maxilla and from the referred materials PRC-5, an isolated maxillary tooth and PRC-6, a braincase.

It was collected in the Ban Saphan Hin site, Nakhon Ratchasima Province, from the Khok Kruat Formation, dating to the Aptian stage of the late Early Cretaceous, about 125-113 million years ago.

Whereas in hadrosaurids, the expanded anterior end of the jugal contacts and overlaps a large sutural area on the maxilla.

[1] The combination of characters seen in the maxilla of Siamodon nimngami indicate that it belongs to a group of iguanodontians more derived than Iguanodon but basal to Hadrosauridae.