Why are Pterosauria, Mosasaurus, Ichthyosauria, and Plesiosaur not Dinosaurs?

There’s usually a misunderstanding: people who are not familiar with dinosaurs may classify Pterosauria, Mosasaurus, Ichthyosauria, and Plesiosaur as dinosaurs. In fact, they are not dinosaurs. So what exactly is a “dinosaur”? Why are they not dinosaurs? These questions can be answered from the following aspects


1, Definition
“dinosaurs” are a type of terrestrial reptile that lived in the Mesozoic era. The strong limbs, long tails, and huge bodies are the portrayal of most dinosaurs.

In 1841, British scientists Richard Owen discovered when studying their fossils that they were similar to a modern lizard but much larger than reptiles such as lizards. Later, he named this type of reptile “dinosaur” by combing the Greek words “deinos” and ”sauros”. In Greek, “deinos” means “formidable” and “sauros” means “lizard”, so the word “dinosaur” means “formidable lizard”.

not Dinosaurs

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Likewise, “Pterosauria” means “winged lizard” in Greek, “Mosasaurus” means “Lizard of the Mosa” in German. “ Ichthyosauria” is “Fish-like lizard”, and “Plesiosaur” is “long neck lizard”.

Although Pterosauria, Mosasaurus, Ichthyosauria, and Plesiosaur all carry “saur” in their names, they are not dinosaurs. Their names describe the relationship with lizards.

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2. Body structure
Studies have shown that dinosaurs are terrestrial reptiles that can walk upright on their hind limbs. Obviously, Pterosauria, mosasaurs, ichthyosaurs, and plesiosaur do not possess this physical condition and ability.

3. Biological classification
Dinosaurs belong to vertebrates and most of them are reptiles, while Pterosauria belongs to flying reptiles, and mosasaurs, Ichthyosauria, and plesiosaur are marine reptiles.
They are not the same kind of creatures, but they have a common ancestor and each took a different evolutionary path.

So don’t confuse them again. Come to Mydinosaurs Company to explore more secrets about ancient creatures.