The Paleozoic Era has five subdivisions divided into periods, during which various events of great biological and geological importance occurred. Today we're going to talk about the Devonian Period . This period lasted approximately 56 million years, during which our planet underwent a great number of changes, especially in terms of biodiversity, but also geologically.
In this article we are going to focus on telling you the characteristics, climate, geology, flora and fauna of the Devonian period.
Key features
This period began approximately 416 million years ago and ended approximately 359 million years ago. As always, it's important to note that the beginning and end of a period are not entirely precise due to a lack of accurate data. This is the fourth period of the Paleozoic Era . The Carboniferous Period follows the Devonian Period.
During this period of time there was a broad development of various groups of animals, especially those that inhabit marine environments. There were also important changes in terrestrial habitats as large plants and the first terrestrial animals appeared. Despite being a period in which life was diversifying to great levels, the Devonian also has a rather dubious reputation for being the period of time in which a large number of animal species became extinct. There is talk of more or less the extinction of 80% of life on our planet.
During this period, a mass extinction event occurred, permanently wiping out many of the species that lived there at the time. Along with the Devonian period, it's divided into different eras. Let's see what these eras are:
- Lower Devonian. It is formed in turn by 3 ages called Lochkovian, Pragian and Emsian.
- Middle Devonian: spanned two ages called Eifelian and Givetian
- Upper Devonian: it was constituted by two cities called Frasniense and Fameniense.
At the end of this period, one of the largest mass extinction events on a planetary scale occurred, causing a significant loss of species, primarily those inhabiting tropical seas. The species most affected included corals, fish, crustaceans, and mollusks , among others. Fortunately, many species living in terrestrial ecosystems were unaffected by the mass extinction. Therefore, the colonization of land continued relatively undisturbed.
Devonian geology
This period was marked by intense tectonic plate activity. Several collisions formed new supercontinents, such as Laurasia. The supercontinent known as Gondwana also formed and persisted. This vast landmass occupied the entire area around the Earth's South Pole . The northern part of the Earth was occupied by Siberia and the immense, deep Panthalassa Ocean. This ocean covered almost the entire Northern Hemisphere.
From the point of view of orogeny, this is a period in which various processes of mountain range formation began, including the Appalachian Mountains and other geological formations.
Devonian period climate
The climatic conditions that existed on our planet during the Devonian period were relatively stable. The predominance of global temperatures was hot and humid with abundant rains. However, arid and dry climates existed within large continental masses.
The average global temperature hovered around 30 degrees Celsius. As time progressed, a slight, gradual decrease occurred, eventually reaching an average of 25 degrees Celsius. Subsequently, at the end of the Devonian period, temperatures dropped to such an extent that one of the ice ages that has transformed our planet throughout history occurred.
Life Insurance
During this period there were significant changes in relation to living beings. One of these most important changes was the definitive conquest of terrestrial ecosystems. Let's first analyze the flora.
Flora
In the period before the Devonian, small vascular plants such as ferns had already begun to develop. These small ferns became more developed in various aspects, the most notable being their size. Other plant forms also appeared on the surface of the continents, such as lycopodiophytes. Some plant species were unable to adapt to the environmental conditions and eventually became extinct.
The proliferation of land plants led to an increase in atmospheric oxygen levels, as plants carried out photosynthesis using chlorophyll pigments. This facilitated the spread of terrestrial life across ecosystems. Furthermore, this increase in oxygen had repercussions for the fauna of the time.
Fauna
Finally, the fauna diversified greatly during the Devonian period, beginning with fish. This group experienced one of the greatest population growths. Many refer to this period as the Age of Fishes. Species such as Sarcopterygians, Actinopterygians, Ostracoderms, and Selachians developed and diversified. This increase in marine biodiversity is also reflected in the Devonian fauna.
Causes of the extinction of the Devonian period
As we have mentioned before, at the end of this period a process of mass extinction occurred. It mainly affected the living forms of the seas. The extinction lasted approximately 3 million years. The causes of this mass extinction were the following:
- Meteorites
- Critical decline in oxygen levels in the seas
- Global warming
- Plant growth or mass
- Intense volcanic activity
Among the reasons we've given, there may be doubts about plant growth. During this period, vascular plants developed to a large size, averaging about 30 meters tall on the surface of the continents. This had a negative consequence, creating an imbalance in environmental conditions, as these plants began to absorb large amounts of water and nutrients from the soil that could have been used by other living beings. This led to a loss of biodiversity.
