Welcome to the true story of the evolution of vertebrates. This book tells about the major adaptations that these animals evolved, in order. For each adaptation, the scientific name of the new group of animals is given, and you can see a cladogram showing the story of evolution.
The three coaches are also here to help you. Pedro will prompt you with questions to consider as you read. Hali will give hints to help you answer these questions. Monty will model sample responses to the questions. Please use the coaches to help you think deeply about the evolution of vertebrates.
The first vertebrates on Earth evolved around 500 million years ago. They were fish in the ocean. Being vertebrates, they had backbones that helped them move more quickly, which means that they could escape from predators more easily.
Ocean fish are reminders of the most primitive vertebrates, but all vertebrates alive today share these first ocean fish as a common ancestor.
Some vertebrates soon evolved four limbs, making them tetrapods. These animals could move more easily, and some could even leave the water for a short time to escape predators. However, the early tetrapods still needed to spend most of the time in the water to keep their skin moist.
Sauropsids could not run very fast, so some of them evolved a hole in their hip socket that helped them have legs that went straight down from their bodies instead of out to the side. These animals are dinosaurs.
Did you know that all birds are considered dinosaurs? Birds evolved from the common ancestor of all dinosaurs, just like humans evolved from the common ancestor of all mammals.
Using the final cladogram on the next page, you can trace back the natural history of each animal included in the cladogram, noticing major adaptations that each animal evolved, in order. Scientists study both fossils and living animals to help discover how animals are related in order to create cladograms like this one.
To learn more about cladograms, you can view a powerpoint presentation or learn about the cladogram my 7th grade students created.
