Dinosaurs in Aragon. Nature in Aragon. Geology Nature of Aragon. Spain.

Dinosaurs or "terrible lizards" inhabited the Earth many millions of years ago.
Some herbivorous dinosaurs reached the largest dimensions that a land animal has ever had. The era of the dinosaurs lasted just over 140 million years.

Suddenly, about 65 million years ago, they suddenly and completely disappeared. Everything we know about them comes from the many fossils that have been found. In Aragon they have appeared in several places where strata from the Mesozoic era emerge, such as in Galve and Peñarroya de Tastavins in Teruel and Arens in Huesca.

Dinosaurs did not appear suddenly but many millions of years had to pass before their presence. Broadly speaking, these would be the stages:

Dinosaurs and their world

When the first fossils of these enormous animals were found, it was mistakenly believed that they were some species of giant lizard. Later, it became clear that they had very little to do with lizards. The first dinosaurs made their appearance in the Triassic period, about 205 million years ago.

In the age of the dinosaurs, the world was very different from how we know it today. The continents were partially united, forming two large land masses. In the northern hemisphere, Europe, part of Asia and North America formed the supercontinent of Laurasia. To the south, Africa and the rest of America constituted another supercontinent: Gondwana.

The climate was also very different then from today. It was much warmer and the subtropical regions extended to latitudes as extreme as those of Alaska or northern Siberia today.

The shallow sea was abundantly inhabited by animals and plants of all kinds, and the humid continental regions were covered with thick vegetation. In drier areas we would have been able to find large forests of palm trees and conifers.

Such conditions were perfect for dinosaurs. Herbivores found food easily, while carnivores ate other reptiles, insects or small mammals.

Primitive Dinosaurs

The family from which dinosaurs emerged was already clearly established in the Triassic period. This group, known as Archeaosaurs, included flying reptiles and the ancestors of today's crocodiles.

The first dinosaurs bore a strong resemblance to crocodiles. The so-called Euparkeria, often considered a precursor to the large carnivorous dinosaurs, looked very similar to a small crocodile. It had the same long tail and characteristic flattened head. On the other hand, he could move much better and was even able to walk, and even run, on his hind legs.

The appearance of the first dinosaurs is not known with certainty. They certainly did not have the formidable appearance of the later species, but they can be divided into two groups:

Little by little, dinosaurs became a clearly differentiated group of animals. Some were monsters bigger than a house.
Others, however, were short and solid animals.
Carnivores were hunters that moved on their hind legs and, although some were as tall as a giraffe, others were no more than a meter tall.

Were There Warm-Blooded Dinosaurs?

Many scientists have wondered how cold-blooded animals could lead such an active life. From what we know about modern reptiles, cold-blooded animals are rather slow. They may have moments when they display great energy, but they spend long periods of time still, lying in the sun if possible.

Some experts believe that dinosaurs may have been warm-blooded animals. In fact, their bones were vascularized, like those of mammals.

His disappearance

The era of the dinosaurs lasted 140 million years. It is a long time, especially when compared to the few thousand years that man has inhabited the earth.

The dinosaurs suddenly became extinct about 65 million years ago. This disappearance, so radical and sudden, remains a mystery.
The disaster that wiped out the dinosaurs also exterminated the giant pterosaurs and large marine reptiles.

Some scientists claim that dinosaurs disappeared because they evolved into such strange forms that they could no longer reproduce or cope with their environment. It is also possible that the environment evolved towards adverse conditions.

A modern theory states that it may have been due to the impact of a meteorite, which would have raised such a cloud of dust that the light and heat of the sun would not have reached the earth for a long time. Dinosaurs, cold-blooded animals, would not have endured such climate change. However, this does not explain why marine reptiles also disappeared.

The Landscape

The era of the dinosaurs coincides with the Mesozoic era and covers three geological periods: the Triassic, Jurassic and Cretaceous. Each of these periods lasted millions of years and important changes occurred in the life forms that populated the Earth.

During the Triassic period, the climate was semi-tropical throughout the planet. Most of the continents were desert, but here and there oases of conifers and tree ferns could be found.

During the Jurassic period, the climate became wetter and warmer. The lands became populated with plants and ferns spread everywhere. The ornithischian dinosaurs were very numerous on the continents, and the first bird made its appearance: the Archaeopteryx.

The climate of the Cretaceous was similar to that of the Jurassic. The vegetation was more varied, and included flowering plants. Then many of the trees we know today made their appearance.