The Ordovician period is a division of the geologic time scale that extends from approximately 485,4 to 443,8 million years ago. During this period, Earth was dominated by shallow, warm oceans, with a warmer climate than today. Marine life was diverse, with the presence of trilobites, brachiopods, mollusks, and corals.
The flora of the Ordovician period consisted primarily of marine algae, as the first land plants were still developing. The fauna, however, was characterized by the presence of marine invertebrates, such as the aforementioned trilobites and brachiopods, as well as primitive fish. This period was also marked by the first great mass extinction, which eliminated many marine species. Geologically, the Ordovician period was marked by intense tectonic activity, with the formation of mountain ranges and the emergence of large ocean basins.
Animals of the Ordovician period: characteristics, diversity and evolution of marine life.
During the Ordovician period, which occurred approximately 485 to 443 million years ago, marine life underwent significant changes and evolution. The animals that inhabited the seas during this period possessed unique characteristics and contributed to the diversity of marine fauna.
The fauna of the Ordovician period was marked by a great diversity of marine organisms, including trilobites, mollusks, brachiopods, corals, and echinoderms. Trilobites, for example, were marine arthropods that dominated the oceans of the time, exhibiting a wide variety of shapes and sizes.
Animals from the Ordovician period were essential to the development and evolution of marine life. They contributed to the formation of complex ecosystems and played important roles in the ocean food chain. Furthermore, the diversity of these animals allowed them to adapt to different marine environments and occupy diverse ecological niches.
Throughout the Ordovician period, marine life underwent a process of evolution and adaptation, resulting in significant changes in marine fauna. New species emerged and diversified, contributing to the richness and complexity of the marine ecosystems of the time.
In short, the animals of the Ordovician period exhibited unique characteristics, contributed to the diversity of marine fauna, and played a fundamental role in the evolution and adaptation of life in the oceans. This period was marked by an explosion of diversity and evolution of marine life, which directly influenced how marine ecosystems developed throughout Earth's history.
Main events and features of the Ordovician period in the geological history of the Earth.
The Ordovician Period, which occurred between approximately 485 million and 443 million years ago, was marked by important events and features in Earth's geological history. During this period, the supercontinent Gondwana continued to move toward the South Pole, resulting in a colder and drier climate in many regions.
One of the hallmarks of the Ordovician was the explosive diversification of marine life. The seas teemed with a wide variety of organisms, including trilobites, brachiopods, graptolites, and mollusks. This diversity of marine fauna contributed to the formation of extensive coral reefs in some coastal areas.
However, the Ordovician Period was also marked by major mass extinctions. One of the most significant occurred at the end of the Ordovician, resulting in the loss of approximately 60% of marine species. The causes of this extinction are still debated among scientists, but it is believed that climate change and tectonic events may have played a role.
In geological terms, the Ordovician was characterized by the continuous movement of tectonic plates and the formation of mountain ranges in various parts of the world. These geological processes contributed to the erosion of mountains and the deposition of sediments in marine basins, creating new layers of sedimentary rocks.
As for flora, land plants were still in the early stages of evolution during the Ordovician. Mosses and green algae were the main forms of terrestrial vegetation, while dense forests of vascular plants had not yet developed.
In summary, the Ordovician Period was a period of great diversification and extinction in the history of life on Earth. Climate change, tectonic events, and the evolution of marine and terrestrial life were prominent features of this geological period.
Environmental impacts of the Ordovician extinction: changes that affected marine life.
The Ordovician Period is a division of the geologic time scale that occurred approximately 485 to 444 million years ago. During this period, the Earth underwent several environmental changes that directly affected the marine life that inhabited the oceans.
One of the main causes of the extinction at the end of the Ordovician was large-scale glaciation, which led to significant global cooling. This resulted in a decrease in ocean temperatures, negatively affecting several marine species. Furthermore, the decrease in oxygen availability in the seas also contributed to the mass extinction of many marine organisms.
Another important factor was rising sea levels, caused by the formation of continental glaciers. This led to the flooding of coastal areas and the loss of essential habitats for many marine species. As a result, the biological diversity of the oceans was significantly reduced, with many species unable to adapt to the new environmental conditions.
In summary, the environmental changes that occurred during the Ordovician extinction had a devastating impact on marine life, leading to the mass extinction of many species. Glaciation, decreasing ocean temperatures, reduced oxygen availability, and rising sea levels were some of the main factors contributing to this catastrophic event.
The characteristics of the environment during the Paleozoic Era: climate, fauna and flora.
The Ordovician Period was a significant period during the Paleozoic Era, occurring approximately 485 to 443 million years ago. During this period, the climate was warmer than today, with a significant increase in global temperature. Tropical regions were covered by shallow, warm seas, while the polar regions were more temperate.
The fauna during the Ordovician Period was diverse, with a wide variety of marine organisms, including trilobites, brachiopods, mollusks, and corals. Trilobites, in particular, were a dominant group, with a wide variety of shapes and sizes. Furthermore, the first fish began to appear in the oceans, representing an important milestone in the evolution of life on Earth.
The flora during the Ordovician Period consisted primarily of marine algae and primitive land plants such as mosses and lichens. Land plants were beginning to diversify and colonize new environments, paving the way for the evolution of forests and terrestrial ecosystems that would emerge later in the Paleozoic Era.
In summary, the Ordovician Period was a time of significant changes in climate, fauna, and flora, marking an important transitional period in the history of life on Earth.
Ordovician period: characteristics, geology, flora, fauna
O Ordovician period It was one of the six periods that made up the Paleozoic Era. It was located immediately after the Cambrian and before the Silurian. It was a period characterized by high sea levels, proliferation of life in marine ecosystems and a drastic reduction in biodiversity at the end of the period resulting from an extinction event.
The animals that dominated the fauna were primarily arthropods, cnidarians, mollusks, and fish. Although important events occurred during this period, it is one of the least-known geological periods.
However, this is changing as more and more experts are deciding to delve into this interesting and important period in Earth's geological history.
General features
Duration
The Ordovician period lasted approximately 21 million years, extending from about 485 million years ago to about 443 million years ago.
Climate variations
It was a period of significant climatic variations between its beginning and end. At the beginning of the period, temperatures were quite high, but over time, thanks to a series of environmental transformations, temperatures dropped significantly, even reaching glaciation.
Mass extinction
At the end of the period, an extinction occurred that wiped out 85% of the species of living beings at the time, essentially in marine ecosystems.
divisions
The Ordovician period was divided into three periods: Lower, Middle, and Upper Ordovician. Between these three epochs, there were a total of seven eras.
Geology
One of the essential characteristics of this period is that, for almost its entire duration, sea levels were the highest the planet has ever seen. During this period, there were four supercontinents: Gondwana (the largest of all), Siberia, Laurentia, and the Baltic.
The northern hemisphere of the planet was occupied mainly by the great ocean Panthalasa and contained only the supercontinent Siberia and a very small part of Laurentia.
In the southern hemisphere was the supercontinent Gondwana, which occupied almost all of the land. Also here were the Baltic and part of Laurentia.
Similarly, Gondwana began to fragment. A small piece began to break away. Today, that piece of land corresponds to China.
The oceans that existed at the time were:
- Paleo Tethys: surrounding the supercontinent Siberia
- Panthalasa: also around Siberia and occupying almost the entire northern hemisphere of the planet.
- Lapetus: Also known as Iapetus, it was located between the supercontinents Laurentia and Baltic. In the late Ordovician period, its size decreased due to the two landmasses moving closer together.
- Rheico: located between Gondwana and other supercontinents, such as Laurentia and Baltic, which would later unite to form the supercontinent Laurasia.
The rock fossils recovered from the Ordovician have mainly sedimentary rocks.
During this period, one of the most recognized geological phenomena occurred: the Taconic orogeny.
Taconic Orogeny
The Taconic orogeny was produced by the collision of two supercontinents and lasted 10 million years, from about 460 million years ago to about 450 million years ago.
It was a geological process that resulted in the formation of the Appalachian Mountains, a mountain range that extends across eastern North America, from part of Canada (Newfoundland Island) to the state of Alabama in the United States.
This geological phenomenon owes its name to the Taconic Mountains, which belong to the aforementioned range.
Time
In general, the climate during the Ordovician period was warm and tropical. According to experts in the field, temperatures recorded on the planet were much higher than today. There are even indications that temperatures of 60°C were recorded in places.
However, toward the end of the period, temperatures dropped so much that a major glaciation occurred, primarily affecting the supercontinent Gondwana, which at the time was in the planet's southern hemisphere, near the South Pole. It lasted approximately 0,5 to 1,5 million years.
Due to this process, a large number of animal species that were unable to adapt to the new environmental conditions became extinct.
Recent studies suggest that the glaciation extended as far as the Iberian Peninsula. This contradicts the belief that the ice was limited to areas near the South Pole.
The causes of this glaciation remain unknown. Many cite the decrease in carbon dioxide (CO2) concentrations as a possible cause, as its levels dropped during this period.
However, studies on the subject are still being carried out to answer questions about the causes.
Lifespan
During this period, there was a great diversification of life, especially that which developed in the sea. In the Ordovician, a large number of genera appeared, giving rise to new species.
Flora
Considering that during this period, life on Earth developed primarily in marine habitats, it's logical that most representatives of the Plantae kingdom were also present there. However, it's important to clarify: During this period, representatives of the Fungi kingdom (fungi) were also present.
Green algae proliferated in the seas. Similarly, certain species of fungi were also present, fulfilling the function they perform in all ecosystems: decomposing and disintegrating dead organic matter.
The history of terrestrial ecosystems was different; it was practically non-existent. However, there were small plants that began to colonize the continent.
These plants were primitive and very basic. They were non-vascular, meaning they lacked conducting vessels (xylem and phloem). Because of this, they had to remain very close to water to have good water availability.
These types of plants resemble modern liverworts, so called because their shape resembles the human liver.
Wild life
During the Ordovician period, wildlife was truly abundant in the oceans. There was a great diversity of animals, from the smallest and most primitive to the most evolved and complex.
Arthropods
This was a fairly abundant edge in the Ordovician. Representatives of this edge include trilobites, brachiopods, and sea scorpions.
Trilobites and brachiopods had a large number of specimens and species circulating in the Ordovician seas. In addition, there were some species of crustaceans.
Molluscs
The mollusk frontier also underwent a major evolutionary expansion. The seas included nautiloid cephalopods, bivalves, and gastropods. The latter moved to the seashore, but breathing through gills, they couldn't survive on land.
Fish
Although it is true that fish existed in the Cambrian, in the Ordovician, jawed fish began to appear, the best known of which was Coccosteus.
Corals
In the Ordovician period, solitary corals are no longer appreciated, but they began to group together to form the first coral reefs of which we have record.
These were composed of coral specimens, as well as several varieties of sponges, which had already been diversifying since the previous period, the Cambrian.
Ordovician–Silurian mass extinction
It became known as the first major extinction for which fossil records are kept. It occurred about 444 million years ago, at the boundary between the Ordovician and Silurian periods.
As with many other processes in the prehistoric era, experts can only conjecture and theorize about why they happened.
In the case of this extensive extinction process, the main causes are related to the modification of environmental conditions prevailing at the time.
Decrease in atmospheric carbon dioxide
Many experts agree that the decrease in this greenhouse gas resulted in a decrease in ambient temperatures, which eventually triggered a long glaciation, in which only a low percentage of species survived.
Decrease in sea level
This appears to be another factor that led to the definitive extinction of many genera and species of living beings. This process was triggered by the convergence of the large land masses (supercontinents) that existed at the time.
In this case, due to continental drift, the supercontinents Laurentia and Baltic were approaching each other until they collided.
This caused the Lapetus (Iapetus) Ocean to close in its entirety, causing a decrease in sea levels and, of course, the death of all living species that thrived on its shores.
Glaciation
This is the main reason experts use when discussing the Ordovician extinction. It is believed to have been linked to the decrease in atmospheric carbon dioxide.
The most affected continent was Gondwana, whose surface was covered by a large percentage of ice. This obviously affected the living beings that lived on its shores. Those that survived did so because they managed to adapt to this new variation in environmental conditions.
Supernova explosion
This is another theory about this extinction. It was developed during the first decade of the 21st century and posits that a supernova explosion occurred in space at that time. This resulted in Earth being flooded with gamma rays from the explosion.
These gamma rays caused a weakening of the ozone layer, as well as the loss of life forms found in coastal areas, where there is little depth.
Consequences
Regardless of the causes that led to the Ordovician mass extinction, the consequences were truly catastrophic for the planet's biodiversity.
It is to be expected that the most affected organisms would be those living in water, since there were very few, if any, in the terrestrial habitat.
It is known that approximately 85% of the species that existed on the planet disappeared at that time. Among those that became almost completely extinct are brachiopods and bryozoans, as well as trilobites and conodonts.
Likewise, large predators that swarmed in the waters became extinct, such as those of the order Eurypterida, which belonged to the extreme end of the arthropods and were large.
Another example is Orthoceras, a genus belonging to the mollusc family. Both were fearsome predators of smaller organisms.
Their disappearance constituted a positive change for the life forms that were their prey, which could thrive and begin to diversify (of course, those that survived the extinction).
divisions
The Ordovician period was divided into three periods or series: Lower Ordovician (early), Middle Ordovician, and Upper Ordovician (Late).
Lower Ordovician (Early)
It is the first subdivision of the Ordovician period. It lasted approximately 15 million years, extending from about 485 million years ago to about 470 million years ago.
In turn, he found himself divided into two eras:
- Tremadociense: lasting 8 million years.
- Floiense: lasted approximately 7 million years.
Middle Ordovician
It lasted approximately 12 million years. It extended from about 470 million years ago to about 458 million years ago. It was divided into two ages:
- Dapingian: happened about 470 million years ago to about 467 million years ago.
- Darriwilliense: happened about 467 million years ago to about 458 million years ago.
Upper Ordovician (late)
It was the last period of the Ordovician period. It lasted approximately 15 million years, extending from about 458 million years ago to about 443 million years ago.
The Upper Ordovician was formed by three ages:
- Sandbiense: which lasted about 5 million years.
- Katiense: covered about 8 million years.
- Hirnantiense: lasting 2 million years.
References
- Benedetto, J. (2018). The continent of Gondwana through time. National Academy of Sciences (Argentina). 3rd edition.
- Cooper, John D.; Miller, Richard H.; Patterson, Jacqueline (1986). A Journey Through Time: Principles of Historical Geology. Columbus: Merrill Publishing Company. pp. 247, 255-259.
- Gradstein, Felix, James Ogg, and Alan Smith, eds., 2004. The Geologic Time Scale 2004
- Sepkoski, J. (1995). The Ordovician radiations: diversification and extinction shown by global genus-level taxonomic data. Society for Sedimentary Geology.
- VVAA (2000). Dictionary of Earth Sciences. Complutense Publication.
- Webby, Barry D. and Mary L. Droser, eds., 2004. The Great Ordovician Biodiversification Event (Columbia University Press).