How Many Types Of Dinosaurs Were There?
Dinosaurs are one of the most popular groups of extinct animals. Their grandeur, their large size and their varied shapes make that, although we have never lived with them, we are fascinated by these creatures. The different types of dinosaurs are part of the collective imagination nowadays.
Dinosaurs are present in many movies, series and books of our popular culture. Therefore, many of us can easily recognize a Triceratops , a Tyrannosaurus or a Stegosaurus. But do we know what types of dinosaurs existed? What’s the difference between them? What times did they live in? We will answer all these questions and many more in the following lines.
Origin and expansion of dinosaurs
The first fossil remains of dinosaurs date back to about 230 million years. This is approximately 20 million years after the Permian-Triassic mass extinction destroyed 95% of life on Earth, including trilobites.
When dinosaurs first appeared, they weren’t the dominant land animals. Most of the resources were consumed by various types of archosaurs and therapsids, animals related to dinosaurs but with different characteristics.
However, dinosaurs gradually gained an evolutionary advantage: in the Jurassic period, they were already the dominant terrestrial vertebrates. At the beginning of its existence, all the continents were united in a single land mass known as Pangea. As a result, the terrestrial fauna was more or less uniform, including dinosaurs.
Continental drift fulfilled its role and little by little the configuration of the continents became more similar to the current one. This caused a great diversification in the types of dinosaurs that existed on Earth, as we will see below.
The 2 Great Types of Dinosaurs
Throughout the 19th century, the discovery of fossils of large dinosaurs opened the door to past worlds. Fossils were not just a recognition of theories of evolution, but an opportunity to discover their mechanisms. In 1887, paleontologist Harry Seeley established that dinosaurs could be divided into 2 large groups.
On the one hand, we have saurischians – or reptile-hipped dinosaurs. These animals had a triangular pelvis, oriented towards the upper body, similar to that of modern reptiles.
On the other hand, there are the Ornithishans – or bird-hipped dinosaurs. Its pelvis was similar to that of modern birds, that is, facing the back of the body. In the next section, we will tell you more facts and characteristics of these 2 large groups, as well as some species of dinosaurs that belong to them.
Ornithischians: One of the Bird-Hip Dinosaurs
As we’ve already said, Ornithishians are dinosaurs with the hips of a bird. Despite this, they are not the direct ancestors of today’s birds, as their entire lineage disappeared in the extinction that ended the dinosaurs.
The main characteristic of the Ornithishans was their diet: practically all of these dinosaurs were herbivores. Furthermore, they were the dominant group in the Cretaceous, the late period of the dinosaurs. Within this group, we can distinguish the following representatives.
Neornithischia
This group of dinosaurs is incredibly diverse and includes species known as the majestic Iguanodon – one of the first dinosaurs discovered – which could measure up to 10 meters and weigh 3 tons. Also belonging to this group is the well-known Triceratops , a dinosaur with 3 horns on the face, with many similarities to a rhinoceros.
Thyreophora
This is a relatively unknown group of dinosaurs. They were almost all quadrupeds and stood out for having a dorsal armor on the back, with thorns or plates as protection. Within this group, the stegosaurus stands out, a curious dinosaur with incredible bone plates on its back.
Saurischians: the ancestors of birds
The saurischians or reptile-hipped dinosaurs were one of the most varied and numerous types of dinosaurs. It ranged from herbivorous dinosaurs – such as diplodocus – to fearsome predators such as allosaurus.
Saurischians were the most common group of dinosaurs in the Triassic and Jurassic, the periods when dinosaurs emerged and became predominant, respectively.
According to several experts, most birds today are descendants of this group. Therefore, we could say that dinosaurs did not disappear from the face of the Earth, as they live among us covered by feathers. In this group of dinosaurs we find the following representatives.
Theropoda: The Deadliest Types of Dinosaurs
Dinosaurs in this group are of various types, with the common feature of having three toes on the limbs. In the beginning, they were bipedal animals, like the fearsome and highly intelligent Velociraptor. This group later diversified and gave rise to flying dinosaurs such as Pterodactylus .
Within this group were predatory and carnivorous dinosaurs, some as fearsome as Tyrannosaurus rex , the king of dinosaurs who terrorized all animals that lived with him.
Sauropodomorph
Dinosaurs of the Sauropodomorpha group are a type of four-legged dinosaur. They were large herbivores, with an incredible length that could reach 30 meters. Within this group we find Diplodocus or Argentinosaurus , herbivorous dinosaurs with large bodies and very long necks.
In conclusion, we can say that the various types of dinosaurs that have existed can be incredibly varied. These huge reptiles gradually diversified and had different ways of life and food.
