In the Paleozoic era we find several periods. The third of them is the Silurian period. It is located between the Ordovician period and the Devonian period. One of its main characteristics is the intense geological activity that the formation of great mountains had. Regarding the Silurian fauna We also find great evolution of many species at the level of biodiversity. This period of time was reigned with a great amount of changes in all the fauna.
Therefore, we are going to dedicate this article to tell you all the characteristics and evolution of the Silurian fauna.
Silurian period
The duration of this period was approximately 25 million years. It began about 444 million years ago and ended approximately 419 million years ago. It was a great period from a geological point of view. During all this time, the formation of mountain systems that we know today took place, such as the Appalachian Mountains from North America.
During this period, life underwent a significant diversification. The first vascular plants began to appear, and animals underwent significant evolution. Among the animals that evolved the most were corals and arthropods. There was also a process of extinction considered to be of a lesser degree. These events primarily affected organisms in marine habitats. For example, half of the trilobite species became extinct during the Silurian period. This extinction can be compared to the Ordovician fauna.
In terms of climate, the planet's temperatures stabilized considerably. The Silurian climate was predominantly warm. During this time, the glaciers that had formed during the previous period were located more toward the planet's south pole. There is fossil evidence indicating that there was a long period of storms during this time. Following these climatic events, the ambient temperature seemed to decrease. It reached such a point that the environment began to cool slightly, but without reaching the extremes of an ice age. At the end of this period, the climate began to be more humid and warmer with a significant number of precipitations.
Flora and vegetation
As we mentioned before, everything related to life, both flora and fauna, underwent a great deal of change during this period. A massive extinction event occurred during the Silurian fauna, allowing some species to diversify and other genera to evolve. An extinction event helps create new adaptations for surviving species.
Among the flora, we find a large number of algae in marine ecosystems, primarily green algae. These algae had the function of controlling environmental balance, as they were the basis for oxygen generation and the foundation of food chains. During this period, a milestone occurred in plant development. This is the first vascular plants began to appear. These plants are those that have the conducting vessels known as xylem and phloem.
At the beginning of this period, the landscape was far from what we see today. Most of the diversity was found in marine areas. The first plants that developed in terrestrial ecosystems they were required to stay near bodies of water, which allowed them to have greater availability of water and nutrients.
Silurian fauna
At the end of the Ordovician period, there was a mass extinction that affected a large number of existing animals. As we mentioned before, an extinction process helps surviving species generate new adaptations to survive in the new environment. Among the species that survived diversify and adapt to these new environments we find arthropods. The arthropods were the animals that reigned the Silurian fauna.
It is one of the groups that experienced a significant evolution. Approximately 425 fossils have been found representing individuals belonging to this phylum. Trilobites decreased their range and abundance due to the extinction period. During this time Myriapods and chelicerates began to appear for the first time. These animals began to spread throughout all terrestrial territories.
On the other hand, mollusks also underwent some evolution. Among the mollusks that existed at that time, we find bivalve and gastropod species. These animals lived on the seabed and adapted to this environment. We also find echinoderms as animals that managed to adapt after the extinction period. Among the echinoderms, we find crinoids, whose populations eventually declined. These crinoids are considered the first echinoderms and, therefore, the oldest on the planet.
The fish group was able to observe some diversification. During the Ordovician period, ostracoderms appeared, characterized primarily by their lack of jaws. These animals are considered the oldest vertebrates for which fossil records exist. However, during the Silurian period, other types of fish began to appear. Among the Silurian fauna, we find jawed fish known as placoderms. One of their distinctive characteristics is that they have a shell on the front of their body to protect themselves from predators.
Other types of fish that emerged during the Silurian fauna are the acanthodians. They are known as spiny sharks and are organisms similar to both ostracoderms and cartilaginous fish. There is some doubt among scientists about the appearance of cartilaginous fish. Some say they appeared during the Silurian fauna, while others claim they appeared in a later period.
Silurian fauna: coral reefs
Coral reefs were of great importance to the Silurian fauna. It is known that the first coral reefs appeared during the previous period. However, It was during this period of time that they began to expand more and more. The species associated with these coral reefs were able to increase their area of distribution and abundance. This is because this coral reef gave them everything they needed to live.
Thanks to the adaptations of the species around the coral reefs, they were made up of very varied species. Among the most common to observe we have sponges and other species of crinoids that belong to the group of echinoderms.
I hope that with this information you can learn more about the Silurian fauna.