Siamosaurus suteethorni

Overview

Siamosaurus, meaning "Siam lizard" (Siam is the old name for Thailand), was a fish-eating spinosaurid dinosaur that lived approximately 125-112 million years ago during the Early Cretaceous. This predator is special because it's one of the first spinosaurids ever discovered in Asia, proving these crocodile-faced dinosaurs had spread across the ancient world!

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Taxonomy & Classification

• Clade: Theropoda
• Family: Spinosauridae
• Diet: Carnivorous (primarily fish)
• Locomotion: Bipedal

Siamosaurus was related to Spinosaurus, Baryonyx, and Suchomimus.

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Physical Characteristics

Size & Build

• Length: 9-9.5 meters (30-31 feet)
• Height: About 3 meters (10 feet) at the hip
• Weight: 2,000-3,000 kg (2.2-3.3 tons)
• Skull: Long and narrow, crocodile-like

Classic Spinosaurid Features

• Long, narrow snout for catching fish
• Conical teeth that interlock to grip slippery prey
• Likely had strong arms with curved claws
• May have had a low sail or ridge on its back
• Semi-aquatic adaptations for fishing

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First Asian Spinosaurid

Why Siamosaurus Matters

Siamosaurus was a groundbreaking discovery:

• First spinosaurid recognized from Asia!
• Proved spinosaurids lived beyond Africa and Europe
• Shows these fish-eaters spread worldwide
• Helps us understand spinosaurid evolution and migration

The Teeth Tell the Tale

• Siamosaurus was mainly known from teeth at first
• The teeth were clearly spinosaurid type
• Conical, slightly curved, with fine ridges
• Perfect for identifying the family

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Life in Ancient Thailand

The Sao Khua Formation

Siamosaurus lived in a very different Thailand:

• Rivers and floodplains instead of today's jungles
• Abundant fish to eat
• Warm, tropical climate
• Part of the ancient landmass before India collided with Asia

Ecosystem Neighbors

Siamosaurus shared its world with:

• Other dinosaurs of various sizes
• Crocodilians competing for fish
• Large freshwater fish as prey
• Pterosaurs flying overhead
• Turtles in the rivers

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Fishing for a Living

Specialized Hunter

Like its relatives, Siamosaurus was built to fish:

• Narrow snout for quick strikes in water
• Conical teeth grip better than blade-like teeth
• Probably waded in shallow water
• May have struck like a heron at passing fish
• Could also hunt land animals when needed

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Siamosaurus vs. Other Asian Spinosaurids

Not Alone!

Siamosaurus isn't the only Asian spinosaurid:

Spinosaurid	Location	Time
Siamosaurus	Thailand	Early Cretaceous
Ichthyovenator	Laos	Early Cretaceous
Spinosaurid teeth	Japan, China	Cretaceous

Asia had its own family of fish-eating dinosaurs!

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The Mystery Dinosaur

Limited Fossils

There's still much we don't know:

• Mostly known from teeth and vertebrae
• No complete skeleton yet found
• Did it have a sail? We're not sure!
• Exact size estimates are educated guesses
• More fossils needed to fill in the picture

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Discovery & Naming

Thai Discovery

• First described in 1986
• Named by Éric Buffetaut and Rucha Ingavat
• Found in the Sao Khua Formation of Thailand
• Species name "suteethorni" honors Varavudh Suteethorn
• Suteethorn is a famous Thai paleontologist

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Cool Facts

• Siamosaurus was the first spinosaurid found in Asia!
• Its name means "Siam lizard"—Siam was Thailand's old name
• The species name honors a Thai scientist who contributed greatly to paleontology
• Spinosaurid teeth from across Asia might belong to related species
• Thailand was once a great place to be a fish-eating dinosaur
• Siamosaurus shows spinosaurids were more widespread than scientists first thought
• It lived in an ecosystem that would look completely different from Thailand today

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Siamosaurus was the crocodile-faced predator of ancient Southeast Asia—proof that the fish-hunting spinosaurids conquered rivers across the prehistoric world!