Turtle fossil discovery

Researchers recently uncovered a transitional turtle fossil in China.

From the three Odontochely fossils discovered in China, [Li Chun at the Chinese Academy of Sciences] said it was clear the turtle first developed the plastron, or the lower shell that encases the belly, before getting its upper shell, or the carapace.

“The plastron developed first and after it was fully formed, then the carapace developed,” he said.

The reason this is an excellent example of a transitional form is that what we see is basically a turtle without a back shell. It is still clearly a turtle, just not one that is much like what we see today. It seems appropriate that we’re finally discovering these turtle fossils as we close in on the 150th anniversary of On the Origin of Species.

So what we have is a turtle which has body armor on its lower body with the neural plates that were likely predecessors to the fuller body armor found in its modern day descendents. In addition, we see that the order of turtle armor evolution – plastron followed by carapace (its back, essentially) fits perfectly with their embryology: during development, the plastron precedes the carapace.

Turtles, wee!

Do you feel the invigoration?

5 Responses

  1. Wait, wait, I thought the ancestor of turtles was a land dwelling armadillo like fellow?

    Oh, wait, that was last
    month’s
    evolutionary story
    …my bad.

  2. National Geographic briefly discusses alternate theories.

  3. Emphasis on the briefly. So turtles originate in seas near China, utilizing there plastrons to defend them from benthic predators.

    Then they make their way in a few million years to the area around what is now New Mexico, and become land dwellers with carapaces.

    Then they make their way to what is now Scotland, jump back into the water (this time a pond) and begin their journey back to the oceans which they left to develop a carapace.

    Then they remain relatively the same for the next 150 million years or so.

    Sounds as reasonable as any other evolutionary story.

  4. Oh, and a Happy Thanksgiving Michael to you and yours!

  5. That story is unrelated, in essence, to the blog post article. The turtles found in Scotland looked much like the ones studied by Darwin just 175 or so years ago. They help to explain the timeline of turtle evolution in regards to their aquatic adaptation. These recently discovered turtles offer compelling evidence to the evolution of the turtle shell while also showing a wonderful example of a transitional fossil.

    Happy bird day.

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