Placodus
Placodus was a marine reptile that lived about 240 million years ago, during the Middle Triassic. It had a stocky body, a long tail, and a heavy skull with flat teeth for crushing shellfish. It swam in shallow seas and probably spent most of its time on the seafloor looking for food.1
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Fun facts
Placodus had a rigid body because the bones in its spine were dovetailed together, making its trunk stiff.1
Its belly was covered with special armor made of bent, right-angled abdominal ribs, and it had a row of bony knobs above its backbone.1
Placodus was negatively buoyant, meaning it was heavy and could easily stay on the seafloor without floating up.1
Before scientists knew what Placodus looked like, its teeth were mistaken for fish teeth.1
Placodus was slow and clumsy on land because of its heavy body armor, so it probably only came ashore to lay eggs.1
Its short legs probably ended in webbed feet, and it used its flattened tail to push through the water.1
Most asked questions about Placodus
?How big was Placodus?
About 2.5 to 3 metres (8.2 to 9.8 ft) long.1
?What did Placodus eat?
Shellfish like bivalves, plus other hard-shelled prey such as molluscs, brachiopods and crustaceans. It used its chisel-like front teeth to pluck them from the sea floor and its broad, flat back teeth to crush their shells.1
?Was Placodus a dinosaur?
No, Placodus was a marine reptile called a placodont, not a dinosaur. It lived in the sea during the Triassic period.12
?Could Placodus swim?
Yes, it swam using its flattened tail and short legs that probably ended in webbed feet. It was not as good at swimming as later marine reptiles like plesiosaurs, but it was comfortable in the water.1
?Why did Placodus have a rigid body?
Its spine had dovetailed bones that locked together, making its trunk stiff. This helped it stay heavy on the sea floor so it could feed without floating up.1
?When did Placodus live?
About 240 million years ago, in the Middle Triassic period.1
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For dino experts
- Scientific name
- Placodus
- Named by
- Agassiz 18333
- Group
- Other sea reptiles
- Family / clade
- Placodontidae3
- Classification
- Placodontia > Sauropterygia3
- Age of the rocks
- 251 to 227 million years ()3
- Rock formations
- Jena, Wellenkalk, Vossenveld3
- Countries
- Germany, Israel, Poland, Netherlands, Italy, China3
- Fossil records
- 34 in the Paleobiology Database3
- Also known as
- Anomosaurus, Crurosaurus (older names now counted as the same animal)3
- Discovery
- Placodus was named by the Swiss naturalist Louis Agassiz in 1833. He originally thought the fossils were fish teeth.13
Where the facts come from
- Placodus (en.wikipedia.org)
- Fossil Focus: Placodonts – PALAEONTOLOGY[online] (palaeontologyonline.com)
- Placodus in The Paleobiology Database (CC BY 4.0): age, places, rock formations, classification.
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