What are Turtles? - How did turtles get their shells?
Welcome to Quatr.us Study Guides!

What are Turtles?

Seychelles tortoise (Jardin des Plantes, Paris)

The first turtles began to evolve from earlier reptiles about 225 million years ago, during the Triassic period. By about 210 million years ago, they looked pretty much like modern turtles. Turtles are one of the oldest kinds of reptiles that are still around today. Turtles evolved to survive in a very different way from lizards. While lizards evolved to move quickly and flexibly, turtles evolved to move very slowly but safely. Gradually their ribs got wider and wider and their vertebrae grew bigger until they had both top and bottom shells, covered with skin. Their heavy shells slowed them down, but also protected them from bigger animals that might have eaten them. The earliest turtles had teeth, but later turtles gradually evolved to have beaks instead.

Sea Turtle
A sea turtle in Malaysia

During the Triassic period, the climate was good for cold-blooded reptiles like turtles, so they did well and many different kinds of turtles evolved. Some turtles returned to the water like fish and let the water support their heavy shells while they swam about (but even sea turtles still need to breathe air; they don't have gills like fish). Sea turtles gradually evolved to have flippers instead of fingers and toes. But all turtles lay their eggs on land.

Turtles evolved when all of Earth's land was together in one big continent, Pangaea. When Pangaea broke into pieces which floated away from each other to become the modern continents, about 180 million years ago, there were some turtles on each piece, so there are turtles all over the world today. Most of the giant turtles, however, became extinct about 100 million years ago, about the same time as the dinosaurs and possibly for the same reasons.

Bibliography and further reading:

Quatr.us home

LIMITED TIME OFFER FOR TEACHERS: Using this article with your class? Show us your class page where you're using this article, and we'll send you a free subscription so all your students can use Quatr.us Study Guides with no distractions! (Not a teacher? Paid subscriptions are also available for just $16/year!)
Please help other teachers and students find us: link to this page from your class page.
Karen Carr is Associate Professor Emerita, Department of History, Portland State University. She holds a doctorate in Classical Art and Archaeology from the University of Michigan. Follow her on Instagram or Twitter, or buy her book, Vandals to Visigoths.
Cite this page
  • Author: K.E. Carr
  • Title:
  • Site Name: Quatr.us Study Guides
  • Publisher: Quatr.us
  • Date Published:
Did you find what you needed? Ask your teacher to link to this page so other people can use it too! Send it in and win a Quatr.us "Great Page!" award!
Sign up for more free articles and special offers in Quatr.us' weekly newsletter:
We will never share your e-mail address unless you allow us to do so. View our privacy policy. Easy unsubscribe links are provided in every email.
Comment on This Article

Does your class page honor diversity, celebrate feminism, and support people of color, LBGTQ people, and people with disabilities? Let us know, and we'll send you a Diversity Banner you can proudly display!
Looking for more?
Quatr.us is loading comments...
(Comments will appear after moderation, if they are kind and helpful. Feel free to ask questions, and we'll try to answer them.)
Cite this page
  • Carr, K.E. . Quatr.us Study Guides, . Web. 27 April, 2017