Pronunciation: si-am-o-don
Meaning: Siam tooth
Author/s: Buffetaut et al. (2011)
Synonyms: None known
First Discovery: Nakhon Ratchasima, Thailand
Discovery Chart Position: #763
Siamodon nimngami
Not every dinosaur makes it onto postage stamps or museum banners, but those that do are generally well-represented, fossil-wise. Siamodon nimngami might get there if it could lay claim to the plethora of ornithopod teeth and various postcranial elements that are strewn around several sites across Thailand's Khok Kruat Formation. Unfortunately, it can't because they're either terribly eroded and lack defining features or aren't articulated with anything that can be compared to the holotype, so its remains are currently limited to a well-preserved tooth-bearing upper jaw bone and an isolated matching tooth, plus a braincase from the same quarry which can't be referred here with complete confidence. Yet, even with those slim pickings, Siamodon has managed to carve out a small but meaningful spot in the story of iguanodont evolution.
The characteristics of its jaws and teeth indicate that Siamodon belongs to a group of advanced iguanodontians cruising in the Goldilocks zone—not as primitive as Iguanodon, not as specialized as hadrosauroids—and appears to be most closely related to the similar-aged Probactrosaurus from Inner Mongolia. The presence of advanced iguanodontians as early as the Aptian stage of the Early Cretaceous in Asia, as exemplified by Siamodon, suggests they may well have risen on this continent before dispersing to North America, where similar forms such as Protohadros and Eolambia first appeared in the latest Albian and Cenomanian.
The characteristics of its jaws and teeth indicate that Siamodon belongs to a group of advanced iguanodontians cruising in the Goldilocks zone—not as primitive as Iguanodon, not as specialized as hadrosauroids—and appears to be most closely related to the similar-aged Probactrosaurus from Inner Mongolia. The presence of advanced iguanodontians as early as the Aptian stage of the Early Cretaceous in Asia, as exemplified by Siamodon, suggests they may well have risen on this continent before dispersing to North America, where similar forms such as Protohadros and Eolambia first appeared in the latest Albian and Cenomanian.
(Nimngama's Siam Tooth)Etymology
Siamodon is derived from "Siam" (an old name for Thailand) and the Latin "odont" (tooth).
The species epithet, nimngami, honours Mr Withaye Nimngama, the fossil owner who kindly donated them for study.
Discovery
The remains of Siamodon were discovered at a stone quarry in the Khok Kruat Formation at Ban Saphan Hin Village, close to Khorat City, Nakhon Ratchasima Province, northeastern Thailand, by Withaya Nimngam.
The holotype (PRC-4) is a well-preserved left maxilla (tooth-bearing bone from the upper jaw). A tooth (PRC-5) and a braincase (PRC-6) from the same quarry were referred to Siamodon also.
