The Tertiary Period marks the beginning of the Cenozoic Era. It began 65 million years ago and lasted more than 63 million years, until 1.8 million years ago. The Tertiary is made up of 5 epochs :
Each epoch has unique characteristics for climate and geography. The plants and animals changed from epoch to epoch also.
In the early 1800’s a system for naming geologic time labeled only four periods. They were named using the Latin forms of numbers for first, second, third and fourth. The word tertiary means “third.” It was the third period in this system. Today, we use a different system, but the name Tertiary is still common for the first part of the Cenozoic Era. Today’s system looks like this:
Era | Traditional Periods | New Periods | Epochs |
C |
Quaternary Period |
Neogene Period |
Holocene Epoch |
Pleistocene Epoch |
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Tertiary Period |
Pliocene Epoch |
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Miocene Epoch |
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Paleogene Period |
Oligocene Epoch |
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Eocene Epoch |
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Paleocene Epoch |
Tertiary Climate: A Cooling Trend From Tropics To Ice Age
The
beginning of this 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 middle of the tertiary,
during the Oligocene Epoch, the climate began to cool. This cooling
trend continued and by the Pliocene Epoch an ice age had begun.
Period |
Epoch |
Continental Positions |
New Mammals |
N e o g e n e |
Pliocene |
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Miocene |
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P a l e o g e n e |
Oligocene |
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Eocene |
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Paleocene |
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Grasses Support Grazing Animals
The plants of the Tertiary are very similar to the plants that we have today. The warm
climate at the beginning of the period favored dense forests. As the
climate cooled open woodlands and grasslands became abundant. The
grasses were important because they supported huge herds of grazing
animals.
The Rise of The Mammals
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. The mammals became the dominant animals. In fact, the Cenozoic 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 table above shows what mammals came on the scene
with each new epoch.
Hominids: Human Ancestors
During the Pliocene the first hominids appeared; these were our human ancestors!
The Tertiary Was For The Birds
Birds
did almost as well as mammals during the Tertiary Period. Many of the
birds we know today were present. There were also many large flightless
birds that are now extinct. These birds did particularly well before the
mammals developed so many species.
Boney Fish and Sharks Develop New Species
Fish species branched out during the Tertiary Period. Sharks became more plentiful. Trout and bass evolved.
Flowering Plants Means Nectar For Insects
The
insect population increased in the Tertiary Period. Bees and other
insects that lived on pollen and nectar of the flowering plants
prospered.
The Tertiary Period Ends With An Ice Age and Land Bridges
The
cooling climate of the Tertiary Period led to huge glaciers at the
poles. The mountains of the world were also covered by glaciers,
including the newly formed Himalayas and Alps. The huge amounts of water
locked up in the ice lowered the level of the sea and land bridges
appeared:
This enabled migrations of both plants and animals across these land bridges.
The Tertiary period which had begun hot and humid, ended in a cold dry ice age.
The next period is The Quaternary Period
Before the Tertiary Period is the Cretaceous Period
Geologic Time Geologic Time Line
Cenozoic Era
Quaternary
Neogene
Paleogene
Mesozoic Era
Cretaceous
Jurassic
Triassic
Paleozoic Era
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
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