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How turtle shells evolved... twice - Judy Cebra Thomas

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Modern turtle shells are almost as diverse as the turtles themselves. Sea turtles have flatter, lighter shells for gliding through the water. Land-dwelling tortoises have domed shells that can slip free of predators’ jaws. Leatherback turtles have shells without the ring of bone around the edge. So how did the shell evolve? Judy Cebra-Thomas explores the ancestry of the turtle.

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TED-Ed Animations feature the words and ideas of educators brought to life by professional animators. Are you an educator or animator interested in creating a TED-Ed Animation? Nominate yourself here »

Meet The Creators

  • Educator Judy Cebra Thomas
  • Director Cabong Studios, Daniel Finkel
  • Compositor Daniel Freire
  • Narrator Bethany Cutmore-Scott
  • Producer Felipe Grosso
  • Storyboard Artist Edgar Costa, Mateus Contini
  • Editor Daniel Freire
  • Art Director Daniel Freire
  • Senior Animator Daniel Freire
  • Character Designer Daniel Freire
  • Animator Fellipe Teixera, Jessé Alves, Daniel Mauad
  • Composer Matheus Wittmann
  • Sound Designer Matheus Wittmann
  • Illustrator Ricke Ito, Victor Goularte
  • Music Matheus Wittmann
  • Director of Production Gerta Xhelo
  • Editorial Producer Alex Rosenthal
  • Associate Producer Bethany Cutmore-Scott
  • Associate Editorial Producer Elizabeth Cox
  • Script Editor Emma Bryce
  • Fact-checker Laura Shriver
  • See more
Additional Resources for you to Explore
In order to understand the evolution of turtles, biologists are still investigating the carapacial ridge (CR) and its development in turtle embryos. What triggers the transition from pre-turtle to turtle morphology? Studies regarding the origin of turtle shells compare gene expression patterns in the CR to similar patterns in the limb buds of vertebrates with best studied developmental systems. Learn more about how biologists examine the evolution of turtles through studying the genetic and embryonic mechanisms of the CR.

Testudines have been found throughout various continents. Learn more about how the skeletal structure of testudines date back to the Eunotosaurus africanus, pappochelys and the Odontochely semitestacea. For more on the evolution of testudines, check out the Evolutionary origin of the turtle shell. Or for more detailed stages of the testudines’s evolution, click here!

After studying the Eunotosaurus africanus, scientists believe these shells aren't just to protect turtles against predators. Check out this article to learn what turtle shells were initially meant for! For more on the benefits of CR to turtles, check out Why Turtles Evolved Shells

The skeleton of turtles has been modified by an inward folding that brings the shoulders and hips under the ribs. Click here to learn more about the turtle shell’s development!

Can’t imagine how millerattas evolved into chelydra? Check out this illustrated evolution of turtle shells!

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About TED-Ed Animations

TED-Ed Animations feature the words and ideas of educators brought to life by professional animators. Are you an educator or animator interested in creating a TED-Ed Animation? Nominate yourself here »

Meet The Creators

  • Educator Judy Cebra Thomas
  • Director Cabong Studios, Daniel Finkel
  • Compositor Daniel Freire
  • Narrator Bethany Cutmore-Scott
  • Producer Felipe Grosso
  • Storyboard Artist Edgar Costa, Mateus Contini
  • Editor Daniel Freire
  • Art Director Daniel Freire
  • Senior Animator Daniel Freire
  • Character Designer Daniel Freire
  • Animator Fellipe Teixera, Jessé Alves, Daniel Mauad
  • Composer Matheus Wittmann
  • Sound Designer Matheus Wittmann
  • Illustrator Ricke Ito, Victor Goularte
  • Music Matheus Wittmann
  • Director of Production Gerta Xhelo
  • Editorial Producer Alex Rosenthal
  • Associate Producer Bethany Cutmore-Scott
  • Associate Editorial Producer Elizabeth Cox
  • Script Editor Emma Bryce
  • Fact-checker Laura Shriver
  • See more