How many Thai dinosaurs are there, and where were they found?

Since the first bone was found at Phu Wiang in 1976, Thailand has given the world 15 new dinosaur species, all from rocks in the Isan region. Here is which rock layer and which province each one came from.

15 species in about 40 years

As of 2026, 15 dinosaur species new to science have been described from Thailand. The first was Siamosaurus suteethorni, a spinosaur named in 1986, and the two most recent are Nagatitan and Uragasaurus, both announced in 2026.^[5][8][9]

Some are known from much more material than others. Siamosaurus is known only from teeth, so some scientists doubt there is enough to keep it as its own genus, while Phuwiangosaurus is known from bones of many individuals and its body shape is fairly well understood.^[5]

The steady stream of finds comes from decades of fieldwork by Thailand's Department of Mineral Resources and several Thai universities, together with researchers from abroad. Many fossils take years of study before they can be published as a new species.^[9][12]

Why Isan?

Most of Isan sits on the Khorat Plateau, which is built on a very thick pile of sedimentary rock called the Khorat Group. These rocks formed from sand and mud laid down by rivers and lakes during the Jurassic and Cretaceous. In settings like these, dead animals were buried quickly, which is ideal for fossils to form.^[1]

Rock units with their own character and age are called formations. Named Thai dinosaurs come from three formations of the Khorat Group and from the Nam Phong Formation beneath it. The figure below puts the youngest layer at the top.^[1]

The 15 Thai dinosaur species by formation; upper layers are younger. (Simplified: thickness not to scale, only formations with named dinosaurs are shown, ages are estimates, and the list includes names whose validity is debated.)

Dinosaurs layer by layer

The Nam Phong Formation is the oldest in the figure. It produced Isanosaurus, an early long-necked dinosaur from Chaiyaphum province, which zircon dating in 2026 placed in the Early Jurassic.^[11]

The Phu Kradung Formation is usually estimated at about 150 million years old, from the Late Jurassic. The Phu Noi site in Kalasin province produced Minimocursor, a small two-legged plant-eater, and Uragasaurus, the first mamenchisaurid long-necked dinosaur named from Southeast Asia.^[4][9]

The Sao Khua Formation, about 125 million years old and from the Early Cretaceous, has produced the most Thai dinosaurs, especially at Phu Wiang in Khon Kaen province: Phuwiangosaurus, Siamotyrannus, Phuwiangvenator and Kinnareemimus. Vayuraptor comes from Nong Bua Lamphu province, and the teeth of Siamosaurus were first found in this formation too.^[2]

The Khok Kruat Formation is the youngest, about 120 to 100 million years old. Nakhon Ratchasima province produced Siamodon, Ratchasimasaurus and Sirindhorna, plant-eating iguanodonts related to duck-billed dinosaurs, as well as the large predator Siamraptor. Chaiyaphum province produced Psittacosaurus sattayaraki and Nagatitan, a sauropod estimated at about 27 meters long and the largest dinosaur yet found in Thailand and Southeast Asia.^[3][8]

Where to see Thai dinosaurs

The Sirindhorn Museum in Sahatsakhan district, Kalasin province, is a large dinosaur museum that displays many Thai species. It stands near the Phu Kum Khao dig site, where bones of many long-necked dinosaurs were found.^[10]

In Khon Kaen province there is the Phu Wiang Dinosaur Museum and dig sites open to visitors in Phu Wiang National Park. To learn more about each Thai dinosaur, see the Thai dinosaurs page on this site.^[12]

How many Thai dinosaurs are there, and where were they found?

15 species in about 40 years

Why Isan?

Dinosaurs layer by layer

Where to see Thai dinosaurs

Sources and further reading

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