El Devonian period it formed one of the five subdivisions that the Paleozoic era had. This period had a great amount of changes at a geological and biodiversity level throughout the planet. It lasted about 56 million years and various groups of animals were able to develop, especially those in the marine habitat. There were also changes in the habitats of land animals, where large plants and the first land animals also appeared. The Devonian fauna It was known to be the most equestrian by far. Although this period is reputed to have an extinction episode where more than 80% of the species disappeared.
Therefore, we are going to dedicate this article to tell you everything you need to know about the Devonian fauna.
Devonian fauna development
This period was perfect to develop life. And it is that the temperatures were more pleasant during this time and allowed a good development of the fauna and flora. All the seas existing in this period had a high standard of living. And it is that in the oceans those most primitive species such as sponges could develop. Siliceous sponge species began to appear and by flourishing on coral reefs they were able to develop different adaptations. Siliceous sponges have a greater resistance to environmental conditions and the presence of predators.
Coral reefs and benthic algae also played a key role in the development of ocean morphology.A large reef extended thousands of kilometers back then, enclosing an entire continent. The Devonian fauna underwent one of the greatest changes in aquatic ecosystems, with the appearance of nektonic animals. Many of these new animal species were predators.
When there is a new development of a species or adaptation to the environment, pressure is exerted on the trophic chain. That is, if there are new predators that hunt their prey, it promotes a new behavior in the species that need to flee and escape these situations alive. This translates into a period of evolution and adaptation to new conditions that generates a diversification of the genes of animals and plants.
In aquatic ecosystems we have also seen a development of mollusc diversification, leading to the appearance of the first ammonoids. These ammonoids come from the evolution of the nautiloids during the Lower Devonian fauna. The nautiloids persisted although with less diversity and abundance.
Aquatic Devonian fauna
In freshwater habitats, bivalves began to proliferate and invade. At that time, trilobites began to gradually decline, although new life forms were still emerging. There were some large trilobites. On the other hand, we had the eurypterid arthropods, which continued to be a fairly important group of predators.
During this expansion, the aquatic fauna of the Devonian experimented with fish breeding. These were especially true of placoderms and sharks. both osteichthians and sarcopterygians, from which terrestrial vertebrates derived, such as actinopterygians. This last group are those that currently predominate in the seas. There are scientists who know Devonian fauna as the age of fish. This is because there are very diverse and well-preserved fossils of remains of these fish, many of them in freshwater lake deposits.
The coelacanths were already dated by this time. In the mid-Devonian fauna, placoderms began to gain ground against ostracoderms. This led to the emergence of Ichthyostega and Acanthostega from the sarcopterygian lineage. These two genera are linked to the transition from fish to tetrapods. This historical transition occurred during the transition between the Devonian and the Middle Devonian fauna. Carboniferous period.
One of the biggest doubts surrounding these fish is whether they were freshwater or marine. This doubt arises because many freshwater fish have been found in deposits of old red sandstone. This area is terrestrial and is formed by a closure of the Iapetus Ocean. This is the main reason why there is doubt about whether these fish were freshwater or marine. The first records of these fish are obtained through marine environments, although most of them they are silurian freshwater fish. From there, different groups of fish emerged.
Colonization of the land
Another main feature that makes the Devonian fauna stand out is the colonization of the land. During the Silurian periodArthropods probably invaded land. However, the earliest data comes from the Early Devonian Rhynie Chert Formation of Scotland. This information preserves an entire community of plants and arthropods that provided a wealth of information about the primitive ecology of early terrestrial environments.
There are numerous species of plants that helped arthropods, including scorpions, mites, and winged insects, to develop and have a suitable ecosystem. Marine and freshwater arthropods had to evolve to terrestrial systems thanks to the development of air respirationHowever, it is difficult to establish a more accurate enumeration of the order in which mites, scorpions, and centipedes arrived in the terrestrial ecosystem using fossil records. All of these arthropods today have extraordinarily diverse descendants, which have adapted to very different environmental conditions, thanks in part to the development of vascular plants.
Before the appearance of vertebrates, the entire primitive world was populated by arthropods. There is a certain amount of controversy that continues to rage in the scientific world regarding the moment when vertebrates ventured out of the water and the reasons that led them to do so. It must be admitted that it is difficult to imagine that an animal that lives in a marine ecosystem would end up developing adaptations to an environment in which it has not lived and does not need to live.
I hope that with this information you can learn more about the Devonian fauna.