Is a Turtle Shell Really Modified Ribs?

It’s thought that the evolution of turtles
A turtle shell is not a shell at all but is made up of specially evolved ribs.

The turtle shell, which is made up of about 50 different bones, actually is an evolutionary modification of the rib cage and part of the vertebral column : r/Awwducational

Solving the riddle of the turtle shell

Turtle Fun Facts

How The Turtle Got Its Shell

Fact Checks Archive, Page 240

Evolution of the carapace by modification of the rib.(a) Basal

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