One of the types of animals that can fascinate children the most are reptiles, which is due to several reasons. First of all, these are animals that, at least at first glance, differ greatly from the animals they are usually more used to seeing, such as mammals or birds. And, secondly, due to a type of reptile that, despite being extinct, is especially striking due to its large size: dinosaurs.
What characteristics do reptiles have
Reptiles are animals that are characterized by having a scaly skin formed from keratin . This is a characteristic common to all reptiles, and has its reason for being in the origin of this type of animal. In fact, reptiles evolved from amphibians . Amphibians are characterized by living between water and land. However, millions of years ago, some of these amphibians adapted to terrestrial life, leaving the water permanently. This forced them to adapt to this new environment and, consequently, the changes that characterize current reptiles emerged.
In fact, scaly skin is a distinct adaptation of amphibian soft skin to a drier environment, where they cannot afford to lose water. Likewise, another of the characteristics of reptiles is their way of reproduction, which they do through eggs . However, unlike amphibians, whose eggs are soft because they are laid in water, reptiles have eggs covered with a hard shell. This hard shell is what allows the eggs not to lose their interior water and, being waterproofed, they can develop on dry land without problem. In addition, another of the differences with amphibians is that fertilization is carried out internally in all reptiles, which they have in common with birds and mammals.
When did reptiles emerge?
The exact date of the emergence of these animals is difficult to determine. Despite this, after many studies, paleontologists have come to the conclusion that reptiles must have arisen on Earth as such, at least 302 million years ago . This is known thanks to the fossils of a small lizard found in North America, which goes by the name of Petrolacosaurus . The Petrolacosaurus is considered the oldest reptile for which there is data. It lived during the Upper Carboniferous, and its appearance was similar to that of a lizard, with a very thin body that could reach 40 centimeters in length.
Paleontologists agree that, in light of current data, this is the oldest reptile on record. According to his theory, this small lizard would be the origin of reptiles, since it would be the turning point between the ancient amphibians and the new animals that we call reptiles. In fact, this reptile would be the forerunner of all the reptile species that would come later, whether it is extinct reptiles such as dinosaurs, or other types of reptiles that have survived to our time, such as turtles, crocodiles, snakes or lizards.
Indeed, the dinosaurs are reptiles . Specifically, these reptiles lived on Earth during the period known as Mesozoic, which would cover a distance of time from 251 million years ago to 65 million years ago, at which time there was a great extinction that wiped out most of the dinosaurs. In fact, although there are different theories in this regard, most of the scientific community agrees that 65 million years ago a climate change occurred that led to the almost complete extinction of most living species that populated the Earth at that time. In other words, it was not an extinction that affected only dinosaurs, but animals of other types, as well as many plant species, disappeared in an exceptionally short period of time.
This suggests that, most likely, a climate change of such characteristics could only be due to a large-scale natural catastrophe that would have a global and devastating effect. In this way, scientists have come to affirm that, one of the most probable causes, would be the impact of an asteroid against the surface of the planet.. This would have led to the expulsion of a large amount of solid material into the atmosphere, which would have prevented the passage of sunlight, which would in turn lead to lower temperatures throughout the planet and the impossibility of plants being able to perform photosynthesis. Finally, this would have entailed a domino effect from plants to animals, affecting first herbivores and then carnivores, generating the great extinction that took place 65 million years ago and that ended with this type of large reptiles in our planet.