The Evolution of the Turtle Shell Ted Talk

 

The turtle shell has evolved many times throughout the million years. This ted talk shows a great simplification of the evolution of the turtle shell. You can watch the video here. The turtle shell has its advantages and disadvantages. Advantages being a guard against predators but disadvantages include "as the turtle grows, the sutures between the bones of the carapace and plastron spread. Most mammals and reptiles rely on a flexible rib cage that expands to allow them to breathe" (TedTalk). But they had to adapt to the rigid and tight space by having separate abdominal muscles attached to the shell to breathe in and out. 

There are many different turtle shells as they have evolved for different environments. Tortoises have a large domed shell that provides protection and can help them turn right side up if fallen. Sea turtles have lightweight and flat shells making it easier for them to glide through the water with litter energy and the softshell turtle has a soft shell which allows it to go into tight spaces other animals cannot. 

It is theorized that shells first evolved by the ribs thickening and then the creation of a belly plate then into the full shell. 

Ted Talk: https://www.ted.com/talks/judy_cebra_thomas_how_turtle_shells_evolved_twice#t-272952