Life Through Time - Visual Timeline

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This exhibit was researched, written and designed by Richard Paselk, Curator Emeritus.

A Timeline of the Eons’s, Era’s, & Periods

The development of life over the last 3,700 million years of the Earth's history is one of the great stories told by modern science. During most of this time living things left only traces to indicate their existence. Then, about 544 million years ago, during what is referred to as the Cambrian explosion, animals learned how to make hard, mineralized body parts. Suddenly rocks resulting from sand and mud deposits become laden with fossil remains, and our picture of ancient life grows enormously in scope and detail. 

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Archean and Proterozoic Eons

Precambrian - 4,570 to 542.0 Million years ago

Precambrian depiction - painting

G. Paselk


4,570 to 542.0 Million years ago

The Precambrian encompasses nearly 90% of Earth's history, and almost a third of the history of the Universe. It begins with the formation of the Earth from the dust and gas of the solar nebula, includes the origin and early evolution of life, the beginning of plate tectonics, and the development of an oxygen atmosphere. It ends with one of Earth's great extinction events, making way for the development of modern plants and animals.

Phanerozoic Eon

Phanerozoic Eon (542.0 Million years ago to present)

Paleozoic Era

542.0 to 251.0 Million years ago

Cambrian Period

Cambrian depiction - Artwork

Cambrian Explosion
© G. Paselk, 2011

542.0 to 488.3 Million years ago

Sudden appearance of fossil remains referred to as the Cambrian explosion. Marine animals with skeletons make their first appearance in shallow seas.

Ordovician Period

Ordovician depiction - artwork

Ordovician Radiation
© G. Paselk

488.3 to 443.7 Million years ago

More complex shelled animals lived in seas during this period, which ended in a mass extinction.

Silurian Period

 Silurian - depiction - artwork

Silurian Marinescape
© G. Paselk

443.7 to 416.0 Million years ago

A warm climate and high sea level gave rise to large reefs, while on land simple land plants emerged.

Devonian Period

Devonian depiction - painting

Devonian Transition
© G. Paselk

416.0 to 359.2 Million years ago

New predators such as sharks, bony fishes and ammonoids ruled the oceans. On land, scorpions, spiders, wingless insects and the first amphibians were starting to thrive.

Carboniferous Period

359.2 to 299.0 Million years ago

Mississippian Subperiod

Mississippian depiction - artwork

Mississippian Crinoid Meadow
Sarah Hamblin

359.2 to 318.1 Million years ago

During this period, sea lilies dominated the limestone seas and reptiles began to appear along with ferns.

Pennsylvanian Subperiod

Pennsylvanian depiction - artwork

Carboniferous Tropical Forest
Treena Joi

318.1 to 299.0 Million years ago

Coal swamp forests thrived during this period. A dragonfly ancestor lived then with a 29-inch wing inch. 

Permian Period

Permian depiction - artwork

Permian Landscape
© G. Paselk

299.0 to 251.0 Million years ago

Reptiles started to thrive in water and on land and conifer forests appear in this period. The Permian ended with greatest mass extinction event known in Earth's history.

Mesozoic Era

251.0 to 65.5 Million years ago

Triassic Period

Triassic depiction - artwork

Late Triassic Landscape
© G. Paselk

251.0 to 199.6 Million years ago

The Permian extinction event was so severe that entirely new fauna and flora appear in the Triassic. Mammals and dinosaurs started to appear in this period.

Jurassic Period

Jurassic depiction - artwork

Post storm cleanup
Gary Bloomfield

199.6 to 145.5 Million years ago

Ammonites and dinosaurs made a huge comeback after near extinction at the end of the Triassic. The first bird fossils and flying pterosaurs showed up in the fossil record.

Cretaceous Period

Cretaceousn depiction - artwork

End of an Era
G. Paselk

145.5 to 65.5 Million years ago

The first flowering plants appeared at the end of the Mesozoic era, along with the extinction of dinosaurs, pterosaurs, mesosaurs and ammonoids, to name a few.

Cenozoic Era

65.5 Million years ago to present

Paleogene Period

Paleogene depiction - artwork

Mid-Paleogene scene with grazing Mesohippus
Treena Joi

65.5 to 23.03 Million years ago

Primitive mammals and birds began to flourish. The Paleogene includes what used to be the first part of the Tertiary.

The Paleogene has three divisions:

Paleocene Epoch (65.5 to 55.8 Million years ago)
Eocene Epoch (55.8 to 33.9 Million years ago)
Oligocene Epoch (33.9 to 23.03 Million years ago)

Neogene Period

Neogene depiction - artwork

Neogene Scene
Kellan Korcheck and M. Royce

23.03 Million years ago to present

Mammals evolved in oceans and on land. The Neogene case now includes Geologic time up to the present, covering what used to be the later Tertiary and the Quaternary, but is now the Neogene and the Quaterary.

The Neogene has two divisions:

Miocene Epoch (23.03 to 5.332 Million years ago)
Pliocene epoch (5.332 to 2.580 Million years ago)

and the Quaternary also has two divisions:

Pleistocene Epoch (11.700 yrs ago to 2.58 Million years ago)
Holocene Epoch (11.5 thousand years ago to present)

Read more:
Neogene Description and Visuals

Museum Case Index:
Case #13 - Neogene Subperiod

Neogene Audio Tour:

Listen to a detailed account of changing continents and the animals that inhabited them.

Note: If you have trouble hearing the audio tour try downloading first than playing.  The audio goes with the image of the case below. 

Image of the Neogene Case:

Picture of the Neogene Case at the museum


Prehistoric Mammals of the Cenozoic

65.5 Million years ago to present

Six cases highlight major mammal groups found in North America over the entire Cenozoic.


Diversify and Conquer

Museum Case Index:
Case #14 - Carnivores


Before the Cart

Museum Case Index:
Case #15 - Horses


Grass Roots Movement

Museum Case Index:
Case #16 - Herbivores


Unforgettable Faces

Museum Case Index:
Case #17 - Probocedians


What's the Big Idea?

Museum Case Index:
Case #18 - Giants

Pleistocene Extinctions

Close Encounters with Mankind

Museum Case Index:
Case #19 - Pleistocene