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Looking at how modern animals are similar to or different from animals that lived millions of years ago.
Did you know that the tiny, chirping birds in your backyard are actually the distant cousins of the giant, scaly Tyrannosaurus Rex?
To understand the past, scientists look at fossils. A fossil is the remains or impression of a prehistoric organism preserved in petrified form or as a mold in rock. Think of fossils like nature's photographs! By looking at the bones of an animal that lived years ago, we can see how big it was and what its body looked like. We call these animals prehistoric. When we compare these old bones to animals living today, we see that many modern animals look like 'updated' versions of their ancestors. These changes didn't happen overnight; they took millions of years through a process called evolution.
Quick Check
What is a fossil, and why is it useful to scientists?
Answer
A fossil is the remains of an ancient living thing, and it helps scientists see what animals looked like millions of years ago.
Animals have traits, which are qualities like fur color, ear size, or tooth shape. Over time, these traits change to help the animal survive in its environment. This is called adaptation. For example, the Woolly Mammoth lived during the Ice Age. It had very thick fur and tiny ears. Why tiny ears? Because big ears let heat out, and the mammoth needed to stay warm! Today, its relative, the Elephant, lives in hot places. It has very thin skin and huge ears that it flaps like fans to stay cool. Even though they are related, their traits changed because their homes were different.
Let's look at how ear size helps with temperature: 1. Prehistoric Mammoth: Lived in F weather. Had small ears to keep heat inside. 2. Modern Elephant: Lives in F weather. Has large ears to let heat escape. 3. Result: The trait (ear size) changed to fit the weather.
Quick Check
Why did the Woolly Mammoth have smaller ears than a modern elephant?
Answer
To keep its body heat inside so it could stay warm in the cold Ice Age.
Why are some animals still here while others are gone? When an environment changes—like getting much hotter or losing its water—animals must adapt. If a species can change its traits over many generations, it might survive. However, if the change happens too fast and the animals cannot adapt or move, they may become extinct. Extinct means there are no more of that kind of animal left alive on Earth. The dinosaurs became extinct because they couldn't survive the massive changes to Earth's climate, but the ancestors of birds were small and hardy enough to keep going!
The first horses lived years ago and were only about foot tall! 1. Environment: They lived in thick forests and ate soft leaves. 2. Change: The forests turned into open grasslands with tough grass. 3. Adaptation: Over millions of years, horses grew taller and developed stronger teeth to eat the grass and run faster from predators.
Imagine a brown rabbit living in a forest where it suddenly starts snowing all year long. 1. Problem: The brown rabbit is easy for hawks to see against the white snow. 2. Adaptation: If some rabbits are born with lighter or white fur, they can hide better. 3. Outcome: If the rabbits don't change color over many years, they might become extinct in that snowy area.
What do we call a trait that helps an animal survive in its environment?
If an animal species is 'extinct,' how many are left on Earth?
Modern animals look exactly the same as their ancestors from millions of years ago.
Review Tomorrow
Tomorrow, try to remember the difference between a Woolly Mammoth's ears and an Elephant's ears. Why did they change?
Practice Activity
Draw a picture of a modern animal (like a cat or a bird) and then draw what you think its ancestor might have looked like years ago!