Happenings During the Cenozoic (65 Million Years Ago to Present)

Time:

65 million years ago to today (and continuing!)
Geologic periods (divisions): Tertiary and Quaternary (the past 2 million years)
The Tertiary period is divided into: Paleocene, Eocene, Oligocene, Miocene and Pliocene (from oldest to youngest)
The Quaternary period is divided into: Pleistocene and Holocene
(See the geologic timescale!)

Paleogeography:

  • The Atlantic Ocean continues to widen as new ocean crust is formed at the Mid Atlantic Ridge.
  • India collided with the Asian continent forming the Himalayan Mountains which continue to grow higher today.
  • The African plate pushed into Europe forming the Alps.
  • In North America, the Rocky Mountains formed and the Colorado Plateau was uplifted. When the land of the Plateau uplifted, rivers flowing over it were able to carve deep canyons. For example, the Colorado River carved the Grand Canyon as it flowed across the plateau over 20 million years.
  • Earth's tectonic plates continue to move today by a process called plate tectonics!

Climate:

  • Early Cenozoic climate was warm and humid, much like the end of the Mesozoic and the climate cooled gradually during the Cenozoic.
  • Ice Ages occurred during the past two million years with repeated forming and melting of glaciers and ice sheets called glaciations. The most recent glaciation occurred about 20,000 years ago. Most of the ice sheets that formed during this glaciation melted by about 10,000 years ago.
  • Whenever Earth's climate cooled and ice sheets formed on land, there was less water left in the oceans, thus lower sea level. Sometimes lower sea level caused land that is usually underwater to connect continents. These areas of land, called land bridges, allowed animals to migrate to other continents.
  • Just several hundred years ago a period of warming (called the Medieval Warm Period) and cooling (called the Little Ice Age) affected people and other living things.

Evolutionary Events:

  • Mammals, which had been small and few during the Mesozoic, became more diverse. New mammal species evolved and were able to live in areas and eat foods that had been used by dinosaurs during the Mesozoic.
  • Grass evolved and flourished in the cooler climates of the later parts of the Cenozoic.
  • Horses and other species of grazing animals evolved and ate the newly-evolved grass. The first horses were small, about the size of a labrador retriever.
  • Modern humans and their recent ancestors are called hominids. Thousands of fossils of hominids have been found; the oldest is more than 6 million years old. One early hominid was Australopithecus. The first Australopithecus skeleton found was that of a woman who had been about 25 years old at the time she died. The researchers who found the fossils of this Australopithecus skeleton called her "Lucy". She would have been only three and a half feet tall. Fossils of hominids that are similar to modern humans are called Homo sapiens. Fossils of Homo sapiens are as much as 400,000 years old.
Last modified June 1, 2005 by Lisa Gardiner.

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Mid-Ocean Spreading Ridge

As the Earth cools, hot material from the deep interior rises to the surface. Hot material is depicted in red in this drawing, under an ocean shown in blue green. The hotter material elevates the nearby...more

Plate Tectonics

Many forces cause the surface of the Earth to change over time. However, the largest force that changes our planet's surface is the movement of Earth's outer layer through the process of plate tectonics....more

The Little Ice Age

The Little Ice Age was a time of cooler climate in most parts of the world. Although there is some disagreement about exactly when the Little Ice Age started, records suggest that temperatures began cooling...more

Atacama Desert

Chile's Atacama Desert is one of the driest places on Earth. Much of the desert receives less than 1 millimeter (0.04 inch) of rainfall per year on average, making it 50 times more arid than California's...more

Scientists to Investigate Role of Equatorial Pacific Ocean in Global Climate System

In early March, an international team of scientists will set sail aboard the drill ship JOIDES Resolution on the first of two Integrated Ocean Drilling Program (IODP) expeditions to the equatorial Pacific...more

What’s That Mineral?

Each type of mineral is made of a unique group of elements that are arranged in a unique pattern. However, to identify minerals you don’t need to look at the elements with sophisticated chemical tests....more

Quartz

Quartz is the second most common mineral in Earth’s crust. It is a member of the quartz group, which includes less common minerals such as opal, crystobalite, and coesite. Silica (Si) and Oxygen (O) are...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA