The Paleogene Period
The Beginning of The Cenozoic Era

The Paleogene Period marks the beginning of the Cenozoic Era. It began 65 million years ago and lasted more than 40 million years. The Paleogene is made up of three epochs:

The Paleocene Epoch
The Eocene Epoch
The Oligocene Epoch

Each epoch has unique characteristics for climate, geography, plants and animals.

Era	Periods	Epochs	Millions of Years Ago
C E N O Z O I C	Neogene	Holocene	11,000 yrs ago to present
		Pleistocene	1.8 mya to 11,000 yrs ago
		Pliocene	5 to 1.8 mya
		Miocene	24 to 5 mya
	Paleogene	Oligocene	38 to 24 mya
		Eocene	54 to 38 mya
		Paleocene	65 to 54 mya

Naming the Periods of the Cenozoic

In the early 1800’s, the system for naming geologic time had only four periods. The periods were named using the Latin words for first, second, third and fourth. The word tertiary means “third.” It was the third period in the old naming system and the first part of the Cenozoic Era. The name Tertiary is still used for the early Cenozoic, even though we have a new naming system. Today we use Paleogene for the first part. Look at the chart below to compare the new system with the old.

Era	Periods	Epochs	Traditional periods
C E N O Z O I C	Neogene	Holocene	Quaternary
		Pleistocene
		Pliocene	Tertiary
		Miocene
	Paleogene	Oligocene
		Eocene
		Paleocene

The Climate of the Paleogene Period

The beginning of the Paleogene Period was very warm and moist compared to today’s climate. Much of the earth was tropical or sub-tropical. Palm trees grew as far north as Greenland!

By the end of the Paleogene, during the Oligocene Epoch, the climate began to cool.

The Geography of the Paleogene

On the chart below are some of the major geographic events of the Paleogene. Notice that on this chart, and on most charts of geologic time, the oldest time is located at the bottom.

Epoch	Geographic event
The Oligocene	Australia separates from Antarctica India crashes into Asia creating the Himalayan Mountains Antarctica is covered by glaciers Sea levels are low
The Eocene	North America and Europe separate
The Paleocene	Europe and North America are joined together Australia is joined with Antarctica India is not yet connected with Asia The Atlantic Ocean is small because South America and Africa have just separated

This is how the earth looked at the beginning of the Paleogene Period. Look at the bottom of the chart. See if you can find the geographic events from the Paleocene Epoch. As you read the chart from the bottom to the top, try to imagine the continents moving into their present-day locations.

The Rise of The Mammals

The plants of the Paleogene Period are very similar to the plants that we have on earth today. The warm climate at the beginning of the period was perfect for the dense forest plants. As the climate cooled, open woodlands and grasslands became abundant. The grasses were important because they supported huge herds of grazing animals.

The extinction event at the close of the Cretaceous Period wiped out the dinosaurs, large reptiles, and many other species. This left room for new animals to develop. Mammals became the dominant animals. In fact, the Cenozic Era is often called the Age of Mammals. Most of the main groups of mammals were present by the Eocene Epoch. With the dinosaurs and other large reptiles gone, mammals grew in size, numbers, and diversity. They filled ecological niches in the sea, on land and in the air.

The Appearance of Common Mammals

Many of the animals that we know today evolved during the Paleogene Period. On the chart below you will see familiar animals and the epochs when they first appeared.

Epoch	Appearance of Mammals
Oligocene	Dogs cats pigs toothed whales
Eocene	bats elephant ancestors whales eohippus-the first horse
Paleocene	The condylarths-ancestors of mordern hoofed herbivores rodents the first primates

Terror Birds in the Paleogene

The Paleogene Period favored the birds. New species evolved. There were many large flightless birds that are now extinct including the Terror Birds. These birds did particularly well until the mammals developed so many species. Many of the birds we know today were present in the Paleogene Period.

The terror Birds were huge predators that roamed the forests and plains of the Paleogene. They belonged to the family called Phorusrhacids. They could be as much as 10 feet tall! There were many species most of them originated in South America. Later in the Neogene some of them migrated to North America once the Americas were connected at Panama. Large mammal predators had not yet evolved early in the Paleogene so there was little competition and the big birds dominated.

The Oceans And Lakes of the Paleogene

In the oceans, fish species branched out. Sharks became more plentiful. Trout and bass evolved along with many other fresh water species of fish. Huge lakes formed in the western United States during the Eocene Epoch. The Green River Formation is a famous fossil rich area created by these lakes. Many kinds of fossil fish are found in this rock formation today.

Mammals developed in the oceans, too. Primitive whales, one of the largest mammals, began to develop at this time.

Insects
The insect population increased in the Paleogene Period. Bees and other insects that lived on the pollen and nectar of the flowering plants increased in numbers and variety.

Climate Change

The Paleogene Period had begun with a hot and humid climate, but the climate was becoming cooler and drier. The cooler temperatures were the signal of many changes coming to the earth. The thick tropical forests would not be able to survive the cooler, drier climate.

If we could go back in time and feel the climate at the end of the Paleogene, we would say it was quite warm. Compared to our climate today, it was still pretty hot! The plants and animals could feel the changing climate and as time marched into the next period, many of them would have to adapt or die.

The Paleogene Period is the begining of the old Tertiary

Interested in fossils from the Paleogene Period? Those listed below are some of the Paleogene fossils available for sale from our sister site fossilicious.com.

Knightia Fish

Leaf Fossils

Metasequoia

Shark Teeth

Check out some of the Educational Materials for sale on our sister site fossilicious.com.

Children's Books on Fossils and Geologic Time

Fossil Collections

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