Not all prehistoric reptiles are dinosaurs . Dinosaurs are the most famous prehistoric animals. Since we know of their existence, they have seduced the public because of how striking it is to think that these monsters walked the same ground as us. Their enormous sizes, the ferocity of their teeth and claws, the speed at which they were able to move, and their brutal appearance have captured the imagination of many of us.
This disproportionate fame of dinosaurs means that those people who are not used to reading rigorous content can confuse animal species with dinosaurs that really are not.
What is a dinosaur?
Let’s start by defining what a dinosaur is so that those who have doubts can recognize for themselves when they are talking about a dinosaur and when they are not.
Biology divides living beings into groups that are related to each other according to the evolutionary process they have had and the characteristics that define them. In the case of dinosaurs, although they have many specific and technical features, we can look at a couple of elements that differentiate them from other animals .
Dinosaurs belong to the group of reptiles that live out of water . Of all these terrestrial reptiles they differ by the position of their limbs. Dinosaurs move upright , that is, they have their legs under their bodies (like Tyrannosaurus rex ), not to the sides (like crocodiles). Also, these upright reptiles began to have feathers, and we now know that birds , rather than any other group of animals, are the descendants of the dinosaurs .
Dinosaurs lived in the Mesozoic era, between 251 and 65 million years ago and, in a very superficial summary: they are reptiles that walk upright and live exclusively in the terrestrial environment. That is why there were no marine dinosaurs, nor flying dinosaurs . Let’s look at some examples of animals that have often been considered dinosaurs, but really are not.
Dimetrodon
A reptile from the Permian period, between 299 and 251 million years ago, so it lived before the dinosaurs. As you already know how to identify them, despite their appearance, typical of movies like “Jurassic Park”, they have legs on the sides of their bodies, like the lizards we know today, so they are not part of the group of dinosaurs.
Pterosaur
These extinct animals are the ones that are most often misled. It is very common to take a children’s book about dinosaurs and, in addition to T. rex and some species with a very long neck such as Diplodocus , a Pterodactylus or the giant Quetzalcoatlus appear drawn in the air. These animals lived with the dinosaurs, but, although they are close relatives, they are flying reptiles, in fact, the largest flying animals that have ever existed. But the dinosaurs, we already know, only lived on dry land.
ichthyosaur
It was a marine reptile that reminds us of dolphins. They also lived with the dinosaurs during the Mesozoic, but, in addition to living in the aquatic environment and having fins instead of legs, these open on the sides of the body and not under it.
plesiosaur
Another species of marine reptile with a short tail, a long neck and a small head full of sharp teeth. It is the type of animal that inspired the physical appearance of the Loch Ness monster.
mosasaur
The predator that dominated the seas during the Cretaceous. His appearance in the “Jurassic World” movies has made a large part of the public take him as just another dinosaur. Again, it is a marine reptile and they are closer relatives to snakes than dinosaurs.
References:
Gascó, F. 2021. That was not in my dinosaur history book. Guadalmazán.
M., A. 2021. What is a dinosaur and how is it different from other prehistoric reptiles. nationalgeographic.com.es.
