When my kids asked to learn about dinosaurs and mammoths this year, I happily agreed because prehistoric animals are a favorite topic of mine. We had studied dinosaurs in the past, but not in reference to where they fall in the geologic timeline, so I thought this would be the perfect opportunity to introduce this concept to them and to teach them a little bit about what came before and after the dinosaurs. Before the dinosaurs roamed the earth, there were other equally fascinating creatures that filled the seas and eventually the land. The geologic era that came before the age of the dinosaurs was called the Paleozoic Era.
This post focuses on the Paleozoic Era. Before we started our study of the geologic eras of the Phanerozoic Eon, we learned about fossils, you can find that post here. You can find my post about the Mesozoic Era (the age of the dinosaurs) here, and my post about the Cenozoic Era here.
The Paleozoic Era
The first era of geologic history we studied was the Paleozoic era. The Paleozoic era began around 541 million years ago and is divided up into 6 geologic periods: the Cambrian, the Ordovician, the Silurian, the Devonian, the Carboniferous, and the Permian. The Paleozoic era ended with the largest mass extinction the world has ever seen, about 252 million years ago.
Paleozoic Animals
At the beginning of the Cambrian period, multicellular aquatic life exploded. Invertebrates like gastropods, bivalves, and trilobites filled the oceans. Towards the end of the Paleozoic Era, the first amphibians and reptiles evolved and animal life spread onto land.
Trilobites
Trilobites are one of the earliest known groups of arthropods. These marine creatures appeared during the early Cambrian Period, about 542 million years ago. They flourished in Earth's oceans until the great Permian extinction that marks the end of the Paleozoic Era. Learn more about trilobites with this short video from PBS Eons: The Trouble with Trilobites.
Ammonites
Ammonites are early cephalopods (the class that modern octopuses, squid, and nautiluses belong to) that evolved around 415 million years ago. They were highly successful and were the most abundant type of animal in the early Paleozoic seas, with over 10,000 different species, some surving all the way until the great dinosaur extinction at the end of the Mesozoic Era. They had a hard outer shell, with a soft body inside with protruding tentacles. Check out some of the different shapes and designs ammonites came in with this short video from The American Museum of Natural History: The Amazing Shapes of Ammonites.
Gastropods
Gastropods are the group commonly known as snails and slugs. They have been around for a very long time. The earliest known gastropods evolved near the beginning of the Paleozoic Era, around 500 million years ago, and scientists believe they were likely around even earlier than that. Ancient gastropods are remarkably similar to the snails and slugs we know today.
Meganeura
Meganeura was a genus of massive flying arthropods that closely resemble today's dragonflies. They lived during the Carboniferous Period and were the largest known insects to ever live. The largest species was probably Meganeuropsis permiana, it had a wingspan up to 28 inches, and a body length of about 17 inches! To learn more about these giant insects, check out this video: Meganeura- The Largest Insect That Ever Existed!
Ichthyostega
Ichthyostega was one of the earliest known amphibians. It evolved about 365 million years ago, during the late Devonian Period. While Ichthyostega probably spent the majority of it's time in shallow water and mud flats, it was one of the first true tetrapods (animals with four limbs) and had lungs so it could breathe outside of the water.
Here are a couple videos about Ichthyostega and the evolution of amphibians:
-When Fish First Breathed Air from PBS Eons
-Ancestral Evolution from Icthyostega to Varanops
Hylonomus
Hylonomus is considered the first known reptile. It lived around 312 million years ago, during the late Carboniferous Period. Hylonomus had scales which helped prevent it from drying out in the sun, this allowed it to stray further from the water than it's amphibian ancestors. Hylonomus laid shelled eggs which also played an important role in being able to survive farther from the water. Fish and amphibian eggs lack an outer shell and must be deposited in the water to prevent them from drying out. Early reptiles like Hylonomus were the first animals able to survive on land full time.
Here are a couple videos about Hylonomus and the evolution of eggs:
-How the Egg Came First from PBS Eons
Additional Resources For Learning About the Paleozoic Era
-During the Carboniferous Period in the later part of the Paleozoic Era, the Earth was covered in massive widespread forests. With so much photosynthesis going on, the oxygen levels were much higher than they are today. This allowed for insects and other arthropods to grow much larger than they do now. To hear more about this period of huge arthropods, check out this video about the Carboniferous period: The Age of Giant Insects from PBS Eons.
-The Earth's climate went through a lot of extreme changes throughout the Paleozoic Era due to shifting landmasses, tectonic activity, and the appearance of land dwelling plants. You can read all about it in this article from Sciencing: Climate of the Paleozoic Period.
Learning Activity Ideas:
Amphibian vs Reptile Skin Activity- This is a cool activity you can do to demonstrate the difference between amphibian skin and reptile skin and why the development of scales was an important evolutionary advancement.
For this activity you will need:
-Two hard boiled eggs
-2 cups
-Water
-Food dye
Start by peeling the shell off one of the eggs. The peeled egg will represent amphibian skin. The shelled egg will represent scaled reptile skin.
Fill each cup with an equal amount of water, enough to fill them about half way. Add 8 drops of food coloring to each cup.
Set each egg into a cup and let them sit over night.
The next day, take each egg out of the cup and compare how much dye each one absorbed. Peel the shelled egg and compare again. Then cut each egg in half and compare how deep the dye penetrates into each egg. Discuss how having scales helps protect an animal from environmental toxins and from physical dangers as it moves through it's environment. Also discuss how having scales would help prevent an animal from drying out in the sun.
Sketch Pictures- Look at pictures of what scientists think the amazing animals of the Paleozoic world looked like and try sketching some of your own.
Make a Timeline- Make a timeline with the different periods of the Paleozoic Era and mark when each type of animal evolved.
Make a Lapbook or Display Board- Display what you've learned about the Paleozoic Era on a display board or in a lapbook.
Paleozoic Vocabulary- Make a list of new vocabulary words and terms you came across while studying the Paleozoic Era. Some words you could include are:
-Cambrian explosion: the rapid evolution of species at the beginning of the Cambrian Period
-Permian extinction: the largest know mass die off of species, which occurred at the end of the Permian Period
-Marine: organisms that live in the ocean
-Terrestrial: organisms that live on land
-Tetrapod: animals with four legs
-Arthropod: the animal phylum that includes insects, crustaceans, and arachnids
-Cephalopod: the class of animals that includes squids, octopuses, and nautiluses
-Gastropod: the class of animals which includes snails and slugs
-Invertebrate: an animal lacking a backbone
-Vertebrate: an animal with a backbone
If you enjoyed this post, be sure to check:
Learning About Geologic History- Fossils
Learning About the Mesozoic Era- The Age of the Dinosaurs
Learning About Geologic History- The Cenozoic Era
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