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| Siamosaurus suteethorni |
Found in Thailand and named in 1986, Siamosaurus was the first dinosaur named from the country.
Its long, conical teeth have lengthwise ridges and look much more like the fish-grabbing equipment of a spinosaurid than the steak knives of a T. rex.
We can get a sneak peek that this magnificent fellow's skeleton on display at Thailand’s THAINOSAUR exhibition. The long jaws, sweeping tail, and dramatic pose make it look ready to lunge at you.
There’s just one catch: palaeontologists have never found a complete Siamosaurus skeleton.
Scientists named the dinosaur in 1986 after teeth were discovered in Thailand’s Sao Khua Formation.
Those teeth are long and conical, with ridges running down their sides. They resemble the teeth of spinosaurs, a group of predators often associated with catching fish.
Think less “slice through dinner like a steak knife” and more “grab a slippery meal before it escapes.” Fish is a plausible part of the menu, though the teeth alone cannot tell us everything this particular dinosaur ate.
Siamosaurus has an important place in Thai palaeontology: it was the first dinosaur named from Thailand. But being first does not mean being well known. Without a skull and skeleton securely identified as Siamosaurus, its exact proportions and appearance remain uncertain.
The spectacular mount in this photograph is a reconstruction, showing visitors a scientifically informed possibility rather than a set of excavated bones.
THAINOSAUR describes its dinosaur displays as recreations and also exhibits genuine fossils. They are working with what they've got, and I respect that. It is a wonderful display!
And the tooth story has grown more interesting. In a 2025 study, Thai researchers Kridsanupong Puntanon, Suravech Suteethorn and Adun Samathi examined spinosaurid teeth from Hin Lat Yao on Phu Wiang Mountain, along with evidence from other remains found there, including tail vertebrae.
They compared the fossils’ features and used statistical and evolutionary analyses to investigate where the teeth fit among spinosaurs.
Their conclusion was careful: the Hin Lat Yao spinosaurid may be distinct from Siamosaurus. In other words, Thailand’s spinosaur fossils should not automatically be placed in one dinosaur’s mouth.
The researchers also suggested that Southeast Asia may have played a significant role in the evolution and spread of this remarkable group. That is a proposal for further investigation, not a solved family tree.
So what are we seeing in the photograph? A wonderful way to meet a Thai dinosaur—and the skill of a museum team that turned incomplete evidence into something we can stand beside and wonder at.
The real Siamosaurus has given us its teeth. The rest of its portrait is still waiting underground. Perhaps it knew a good mystery would keep us coming back.
Oh, Thailand... you're officially added to my bucket list! I'd be pretty chuffed to find the skeleton!
That’s part of the fun of fossils. A handful of teeth can reveal a predator in an ancient ecosystem, while leaving just enough unanswered to keep us digging.
Lead Image ID: 2679304243. Reconstructed Siamosaurus suteethorni skeleton at the THAINOSAUR exhibition in Bangkok.
