Question 1

How do you say Cenozoic?

Accepted Answer

Cenozoic is pronounced SEE-nuh-ZOH-ik. The stress falls on the first syllable SEE and again on ZOH. Break it into four parts: SEE, nuh, ZOH, ik, and say it smoothly together. You might also hear people say SEN-uh-ZOH-ik with a short first syllable, and that version is also accepted by scientists.

Question 2

What does Cenozoic mean?

Accepted Answer

Cenozoic comes from two Greek words: kainos, meaning new or recent, and zoe, meaning life. Put them together and you get new life or recent life. The name was given to this era because it represents the most recent chapter of complex life on Earth, defined by the rise and dominance of mammals, birds, and flowering plants after the dinosaurs disappeared.

Question 3

Are we in the Cenozoic Era right now?

Accepted Answer

Yes, we are living inside the Cenozoic Era right now. The Cenozoic started 66 million years ago and is still ongoing. We are currently in an epoch called the Holocene, which is part of the Quaternary period, which is itself part of the Cenozoic Era. So every single human being who has ever lived has lived during the Cenozoic.

Question 4

What ended the dinosaurs and started the Cenozoic?

Accepted Answer

The Cenozoic began when a massive asteroid, roughly 10 to 15 kilometers wide, slammed into the Yucatan Peninsula in Mexico about 66 million years ago. The impact caused global wildfires, blocked sunlight for months or years, and collapsed ecosystems worldwide. About 75% of all species went extinct, including all non-avian dinosaurs. The surviving mammals, birds, and other creatures then had an empty world to evolve into, which is exactly what they did.

Question 5

What animals lived in the Cenozoic Era?

Accepted Answer

The Cenozoic is the age of mammals, so almost every mammal you know evolved during this era, including horses, whales, elephants, cats, dogs, and primates. But the era also produced some extinct giants like Megalodon, the enormous predatory shark, woolly mammoths, saber-toothed cats, and giant ground sloths. Birds diversified enormously too, and some like the terror birds were fearsome predators standing 3 meters tall.

Question 6

How long did the Cenozoic Era last?

Accepted Answer

The Cenozoic Era started 66 million years ago and is still going today, so it has lasted over 66 million years so far. That makes it the shortest of the three great eras of complex animal life: the Paleozoic lasted about 289 million years, and the Mesozoic lasted about 186 million years. But since the Cenozoic is still happening, its total length is not yet determined.

Question 7

What came before the Cenozoic?

Accepted Answer

Before the Cenozoic came the Mesozoic Era, the age of dinosaurs, which lasted from about 252 million years ago to 66 million years ago. The Mesozoic is divided into three periods you might know: the Triassic, the Jurassic, and the Cretaceous. The Cretaceous was the last period of the Mesozoic, and it ended at the exact moment the Cenozoic began, when the asteroid hit.

Question 8

What is the difference between Cenozoic and Mesozoic?

Accepted Answer

The Mesozoic Era, which ran from 252 to 66 million years ago, is known as the age of reptiles because non-avian dinosaurs, pterosaurs, and marine reptiles dominated land, air, and sea. The Cenozoic Era, from 66 million years ago to today, is known as the age of mammals because after the asteroid extinction, mammals took over and diversified into thousands of species. Both eras are part of the Phanerozoic Eon, the overall time period of complex animal life on Earth.

Question 9

Was it warm or cold during the Cenozoic?

Accepted Answer

Both, at different times. The early Cenozoic was extremely warm, with no ice at the poles and tropical forests near the Arctic Circle around 50 million years ago. Then the climate began cooling about 34 million years ago, eventually leading to the Ice Ages of the last 2.6 million years, when giant glaciers repeatedly covered North America and Europe. Today we are in a warmer period between glaciations, but the long-term trend of the Cenozoic includes dramatic swings between warm and cold.

Question 10

Did humans live in the Cenozoic Era?

Accepted Answer

Yes, all of human history takes place during the Cenozoic Era. Our earliest primate relatives appeared around 55 million years ago, early human ancestors began walking upright in Africa about 4 to 7 million years ago, and modern Homo sapiens appeared roughly 300,000 years ago. All of recorded human civilization, from ancient Egypt to today, fits into the last 5,000 or so years of the Cenozoic, which is an almost unimaginably tiny slice of its 66 million year span.

Question 11

What period are we in right now inside the Cenozoic?

Accepted Answer

Right now we are in the Quaternary Period, which is the most recent period of the Cenozoic Era. The Quaternary began 2.6 million years ago and is still ongoing. Within the Quaternary, we are in an epoch called the Holocene, which started about 11,700 years ago when the last major Ice Age glaciation ended. Some scientists also argue we have entered a new unofficial epoch called the Anthropocene because of the massive impact humans are having on Earth's systems.

Question 12

How is the Cenozoic divided up?

Accepted Answer

The Cenozoic Era is divided into three periods. The Paleogene Period runs from 66 to 23 million years ago and includes the early rapid diversification of mammals. The Neogene Period runs from 23 to 2.6 million years ago and covers the evolution of grasslands and early human relatives. The Quaternary Period runs from 2.6 million years ago to today and includes the Ice Ages and the entire history of modern humans.

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