Paleozoic Era
Paleozoic Era: Facts, Timelines & Animals
From the Greek words for “old’ and “life” (παλαιό and ζωή respectively), the Paleozoic Era denotes the earliest of three distinctive geologic eras of the Phanerozoic Eon.
Noted as a time of dramatic evolutionary, climate and geological change, the Paleozoic Era lasted between 541 to 251.902 million years ago. This Era is so diverse and lengthy that it has been further subdivided into six unique geologic periods ranging from the oldest to the youngest.
Periods of the Paleozoic Era include:
- Cambrian
- Ordovician
- Silurian
- Devonian
- Carboniferous (sometimes separated into the Mississippian Period and Pennsylvanian Period; and
- Permian
Paleozoic Time Line
Geology: It All Started with a Little Rock (and roll)
Kicking things off with a bang, the Paleozoic Era started and ended with supercontinents. Early to the party was Pannotia, a supercontinent that subsequently broke up, with research indicating that central Africa was likely located in the polar regions at this time.
Yet, while one falls another is on the rise. Around 510 million years ago, another massive continent was forming and taking shape. By the time the mid-Paleozoic period was nigh, a collision of Europe and North America resulted in the Acadian-Caledonian Uplifts, while a subduction plate was instrumental in uplifting eastern Australia.
Wrapping things up, the late Paleozoic Era was marked by further continental collisions, the result being the formation of the supercontinent Pangaea and other notable formations such as the Appalachian Mountain range, the mountains of Tasmania and the Ural Mountains.
Cambrian Period
Timeframe: 541 to 485 million years ago
Notable For: Period of robust evolution and emergence of new lifeforms
Ranging from between 541 million to 485 million years ago, the Cambrian Period marks the beginning of the Paleozoic era. Notable for an exponential explosion of evolution, the Cambrian Period resulted in the highest number of new organisms and creatures in the history of the planet.
Algae, armored arthropods, like trilobites, and virtually all marine phyla made their debut during this period.
Ordovician Period
Timeframe: 485 to 443 million years ago
Notable For: Biological evolution of many scientific classes still prevalent today, as well as the second deadliest extinction event in Earth’s history.
During this period we see coral, cephalopods and early forms of primitive fish emerge. Among the most common lifeforms during this period were shellfish, snails and trilobites. Towards the end of this period, early-age N. America had collided with Europe, effectively closing off the Atlantic Ocean, while the Glaciation of Africa resulted in a significant reduction in sea levels around the world. Such glaciation is thought to have instigated several extinction-level events, with an estimated 25% of invertebrates and 60% of marine invertebrates going extinct.
Silurian Period
Timeframe: 443 to 416 million years ago
Notable For: Significant evolution of fish, and the first fully terrestrial lifeforms.
As earth recovered from the previous glaciation, we see the emergence of new jawed and jawless fish, as well as the emergence of new freshwater fish. During this period, sea scorpions and arthropods remained the apex predators of oceans and waterways, while land saw for the first time, fully terrestrial creatures and lifeforms such as centipedes, arachnids and fungi.
Vascular plants that surfaced during this period (known as Cooksonia) enabled plants to earn a foothold on land, while the recent rise in sea levels resulted in a significant increase in water-based species.
Of note, this period had four major continents:
Laurentia (North America)
Gondwana: Africa, S. America, Australia, Antarctica, Siberia)
Avalonia (Western Europe)
Baltica (Northern Europe)
Devonian Period
Timeframe: 416 to 359 million years ago
Notable For: Known as “The Age of Fish”, for the “Devonian Explosion” and the Late Devonian Extinction.
This period is most notable for a massive diversification of fish, the likes of which would later evolve into the first-ever tetrapods. Similarly, on land plant flora continued to thrive and evolve, known as the “Devonian Explosion”. This “explosion” resulted in plants developing the ability to produce lignin, enabling them to achieve literal new heights with taller growth and newly evolved vascular tissue. It was from this evolution from which the first seeds and trees emerged on the planet.
As you can imagine, new habitats established unique ecosystems that were the breeding grounds for the first amphibians.
Towards the end of the period, we saw Earth’s second-largest mass extinction event, the Late Devonian Extinction, wiping off around 70% of all species from the face of the Earth.
Carboniferous Period
Timeframe: 359 to 299 million years ago
Notable For: Exceedingly high global temperatures, tropical swamps, highest oxygen levels in Earth's history, the evolution of amniotic eggs
During the Carboniferous period, the earth experienced some of its highest temperatures to date, resulting in dense tropical swamps and a dominance of trees. Interestingly, fungi and bacteria that normally eat and break down tree matter were absent during this time, with the remnants of these trees becoming buried, later forming what would become our modern-day coal deposits.
One of the most notable developments that occurred during this period was the evolution of amniotic eggs, enabling amphibians to migrate inland. As the Carboniferous period wrapped up, the earth experienced a cooling, leading to what we now know as the Carboniferous Rainforest Collapse or the Permo-Carboniferous glaciation.
Permian Period
Timeframe: 299 to 252 million years ago
Notable For: A joining of continents, forming Pangaea, the evolution of conifers, The Great Dying
The last period of the Paleozoic Era was the Permian Period, which started off in spectacular fashion, marked by a joining of the continents to form one supercontinent: Pangaea. Pangaea was as an island in the sense that it was circled entirely by a single ocean, the Panthalassa. This period was marked by a dry and harsh climate, with the supercontinent’s massive interior left unaffected by the temperature-regulating ocean waters.
During the Permian Period, synapsids and diapsids flourished on land, and we saw the emergence of the first coniferous trees. Near this period’s end, however, much of the interior had turned into desert.
The Permian Period ended with a catastrophic event so great that it marked the largest extinction ever, with up to 95% of all lifeforms disappearing. This event is known as “The Great Dying”. Many of the details are still unknown. What we do know is that a monstorous volcanic eruption happened at this time. It is difficult to imagine the size of this event. We can't really think of it as a single eruption. First it lasted for millions of years! It was not a volcano, a hole in the ground that lava comes out of. It was more like the Earth opening up across hundreds of miles all at once. It covered an area of about 3 million square miles, about the size of Australia!
Many scientist beleive that this event triggered a series of changes in the climate of the Earth and the chemistry of the atmosphere and oceans that most living things just could not adapt to.
The Permian Period ended with a catastrophic event so great that it marked the largest extinction ever, with up to 95% of all lifeforms disappearing. This event is known as “The Great Dying”. Many of the details are still unknown. What we do know is that a monstorous volcanic eruption happened at this time. It is difficult to imagine the size of this event. We can't really think of it as a single eruption. First it lasted for millions of years! It was not a volcano, a hole in the ground that lava comes out of. It was more like the Earth opening up across hundreds of miles all at once. It covered an area of about 3 million square miles, about the size of Australia!
Many scientist beleive that this event triggered a series of changes in the climate of the Earth and the chemistry of the atmosphere and oceans that most living things just could not adapt to.
