The era of Mesozoic contains 3 periods where dinosaurs spread and became extinct. These three periods are: Triassic, Jurassic y Cretaceous. Within each period there was a great development of fauna and dinosaurs, especially the Jurassic fauna. Today we are going to talk about the development and extension of the Cretaceous fauna.
If you want to know more about the expansion of the dinosaurs and the Cretaceous fauna, this is your post.
Cretaceous fauna
Throughout the 79 million years that this period lasted And during the two periods it lasted, the Cretaceous fauna was dominated primarily by dinosaurs. At that time, a wide variety of both marine and terrestrial dinosaurs existed. In addition, some fish and invertebrates were also widespread. Mammals during this period were a smaller group, but they began to proliferate in the following period.
We are going to analyze one by one the types of animals that developed during the Cretaceous.
invertebrates
Among all the invertebrates that developed, especially in the marine environment, we can mention mollusks. Among the mollusks, the ammonoids that were cephalopods stood out. Other invertebrates that were widespread were coleoids and nautiloids.
The phylum of the echinoderms had a proliferation during this period. Within this phylum we highlight some of the main species of starfish, echinoids, and ophiuroids. All this information has been gathered thanks to fossil deposits known as amber deposits. These deposits contain a wealth of information about arthropods, including examples that can be related to the extinction of the dinosaursSpecimens of spiders, dragonflies, bees, wasps, butterflies, ants, grasshoppers, and others have been found.
In addition, it is important to know how these marine invertebrates relate to the Paleocene fauna that followed them.
Vertebrates
Vertebrates also had great proliferation during the Cretaceous period. The most prominent within this group were the reptilesWithin the reptile group, dinosaurs stood out, both on land and in the marine environment. These dinosaurs coexisted with marine reptiles and fish.
In terrestrial ecosystems, the mammal group began to develop slowly, and its diversification is related to some species that had been evolving from marine habitats. The same occurred with the bird group. who began to take a prominent role.
Importance of dinosaurs in the Cretaceous fauna
As we have mentioned before, dinosaurs formed an important part of the Cretaceous fauna. And it is that during this time, regarded as the golden age of dinosaurs, Both herbivorous and carnivorous terrestrial dinosaurs and marine dinosaurs developed. Let's analyze each of them.
Land dinosaurs
It was the most diverse group during this entire period. They were divided into two large groups based on their diet. On the one hand, we had the carnivorous dinosaurs, and on the other, the herbivores. that allow us to understand its history and extinction.
Likewise, the Cretaceous dinosaurs were key to understanding the Cretaceous and their evolution.
Herbivorous dinosaurs
They were also known as ornithopods. This group of dinosaurs ate only plants. Within this group, we find predominant species such as:
- AnkylosaursThese dinosaurs were large, sometimes reaching lengths of 7 meters and a height of almost 2 meters. The average weight of these species was 4 tons. To protect themselves from carnivorous predators, their bodies were covered with bony plates that functioned as armor. All this information has been obtained thanks to the fossils found, in which it was possible to see that the front limbs were shorter than the hind limbs. Their heads were similar to a triangle, as their width was greater than their length.
- Hadrosaurs: These dinosaurs are also known as duckbills. They also had a large size between approximately 4 and 15 meters long. They could have a large number of teeth to be able to grind the grass well. On some occasions fossils have been found with a jaw of up to 2000 teeth arranged in rows and all of them were of the molar type. The tail was quite long and flattened. The main purpose of this tail was to maintain balance when moving on two legs to flee from predators.
- Pachycephalosaurs: They were large dinosaurs whose main characteristic was to have a bony protrusion that simulated as if it were a helmet. Its main function was that of protection. In some specimens, the protuberance could reach a thickness of up to 25 centimeters. It was a type of bipedal dinosaur and could reach a length of up to 5 meters and a weight of 2 tons, approximately.
- Ceratopsids: These dinosaurs were quadrupeds. They had horns on their faces. They also had a protruding ridge on the back of their heads that extended to their necks. They grew up to 8 meters tall and weighed up to 12 tons.
Carnivorous dinosaurs
The carnivores include the theropod group. These were large carnivorous dinosaurs and represented the predominant predators. Most of them were large and had highly developed and strong limbs. They were bipedal, and their main characteristic was that they had two front-facing limbs and one back-facing limb.
Of this group of carnivorous dinosaurs it may be the best known Tyrannosaurus Rex. Its importance lies in how it helps us understand the extinction of the dinosaurs.
Flying reptiles
Of the flying reptiles, the best known is the pterosaur. Although many include these animals in the dinosaur group, this is not the case. These animals were the first vertebrates capable of flight. Its size could reach up to 12 meters of wingspan.
Marine reptiles
Another group that developed significantly in the Cretaceous fauna were marine reptiles. They were generally large, between 12 and 17 meters in length. The best known were mosasaurs and elasmosaurids. Elasmosaurids had a number of main characteristics, including a long neck and a large number of vertebrae. They fed primarily on fish and mollusks, which allowed them to adapt to their environment.
On the other hand, mosasaurs were reptiles that were adapted to marine life, and had a very long tail and a vertical fin. These large predators are part of the fascinating Cretaceous marine fauna.
I hope that with this information you can learn more about the Cretaceous fauna.