ERAS

ERAS

Larger than a period but smaller than an eon

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Learning More About Eras!

Timeframe

The different recognized geological Eras:

Era

Since this geological time is split into different divisions, each which lasted millions of years, there is no definite answer to how long this geological time lasted. One thing to note, however, is that we are currently in the Cenozoic Era.

An era is a long unit of geological time, typically characterized by distinct global changes in climate, life forms, and geologic activity.

HOW LONG DID IT LAST?

DEFINITION

GEOLOGICAL ERAS

* Paleozoic Era* Mesozoic Era* Cenozoic Era

Sooo... What was earth like during this time?

Well, it depends what era you're looking at.

Mesozoic Era

Paleozoic Era

Cenozoic Era

MAJOR EVENTS

Paleozoic

Mesozoic

Cenozoic

Hey! It's been really fun learning about the geological time of "Era"! But...

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I'm so glad to hear that! Seems like there is more you want to say though... What is it?

FUN FACTS!!!

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I was just wondering if you possibly had any fun facts you could share with me. I'd love to learn more about this!

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Of course! I'd love to share more. Here are some fun facts I'm sure you'll enjoy: or

Learn more!

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References

DiMichele, William A et al. “The So-Called ‘Paleophytic–Mesophytic’ Transition in Equatorial Pangea — Multiple Biomes and Vegetational Tracking of Climate Change through Geological Time.” Palaeogeography, palaeoclimatology, palaeoecology 268.3 (2008): 152–163. Web. Wilmarth, M. Grace (Mary Grace), and Geological Survey. The Geologic Time Classification of the United States Geological Survey Compared with Other Classifications, Accompanied by the Original Definitions of Era, Period and Epoch Terms. Washington, D.C: Department of the Interior, United States Geological Survey, 1925. Print.

Image Citations

Mesozoic Era

This era was also known as the "Age of Reptiles" because of the present dominance of dinosaurs during this time, this era including the Triassic, Jurassic, and Cretaceous periods.

• Life forms: this era was dominated by all sorts of animals, including dinosaurs, mammals, marine reptiles, birds, and flowering plants.
• Climate: the climate during this time could have been described as warm and humid, there being less difference in temperature between the equatorial and polar latitudes compared to today's age.

Paleozoic Era

This era is marked by the rise of marine life, amphibians, and the first terrestrial plants that were present during this time. This era is also known for including the following periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian.

• Life forms: as mentioned before, this era was dominated by marine life, amphibians, and the first terrestrial plants.
• Climate: during this time one could expect warm weather but later on cooling events would take place, including ice ages during the change of periods.

Cenozoic Era

This era is also referred to as the "Age of Mammals", also encompassing the Paleogene, Neogene, and Quarternary periods. This is also a period that is marked by not only the dominance of mammals, but also the appearance of humans.

• Life forms: this era is dominated by mammals, which includes humans.
• Climate: this era has probably the most wavering climate, changing from warm and wet, to cool and dry, with ice-covered poles. Many different factors could also affect climate in this era.

MASS EXTINCTION!

This era was struck by a mass extinction, otherwise known as the Permian extinction. Occurring during the end of this period (541 million years ago - 252 million years ago), this was the largest mass extinction event recorded in the earth's history. This extinction would wipe out approximately 96% of marine species and 70% of animals on land, that's a lot! With this huge impact on the earth, even forests being wiped, those in which did not return until about 10 million years later.

PANGAEA SEPERATION

This is a pretty well-known major event, one that I am sure you probably already knew before even mentioning it. This event was when the supercontinent Pangea, about 200 million years ago, broke apart, splitting and forming the continents that we know of today.

CLIMATE CHANGE

As mentioned earlier, climate became quite unpredictable, significant fluctuations and the development of an ice age occurring during this time. Unlike the steady and warm climate that the other eras experienced, the Cenozoic era would transition from a warm state with minimal ice caps, to a much colder state that included significant polar ice sheets.

The Precambrian era was the longest, beginning when earth first fromed about 4.53 billion years agp, and then ending approximately 542 million years ago.

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Eras are subdivisions of eons, an example of this being how the Phanerozoic Eon is split into the Paleozoic, Mesozoic, and Cenozoic eras.

There are also other subdivisions of eras such as: Archeozoic era, Proterozoic era, and the Psychozoic era.

The use of "zoic" in the era names (Paleozoic, Mesozoic, and Cenozoic) signifies their basis on fossil life forms!

Geo Park. Paleozoic Era: Devonian. n.d. 2025 February 16. <https://www.geoparcoalpicarniche.org/en/ere_geologiche/lera-paleozoica-il-devoniano/>. Ghose, Tia. Mesozoic era: Age of the dinosaurs. 28 July 2022. 16 February 2025. <https://www.livescience.com/38596-mesozoic-era.html>. Kenny, James. A History Of Life On Earth: The Mesozoic Era. 25 December 2012. 16 February 2025. <https://discover.hubpages.com/education/A-History-Of-Life-On-Earth-The-Mesozoic-Era>. Pappas, Stephanie. Paleozoic Era: Facts & Information. 19 June 2013. 16 February 2025. <https://www.livescience.com/37584-paleozoic-era.html>. Zimmermann, Kim Ann. Cenozoic era: Facts about climate, animals & plants. 8 June 2016. 16 February 2025. <https://www.livescience.com/40352-cenozoic-era.html>.