Question:
How long have turtles been on earth? How did they look like in prehistoric time?
- Asked by Vallerie Ng and Nickee Chung
Answer:

Odontochelys semistestacea, sourced from the internet
According to the latest available information, turtles been on earth for between 200-300 million years. That makes them very very ancient animals. In comparison, the evolution of humankind can be traced back to only 2.5 million years.
The oldest turtle fossil discovered to date was unearthed only as recently as 2007 in China’s Guizhou province. It was estimated to be 220 million years old, was an aquatic turtle and given the name Odontochelys semistestacea. The previous record-holder was a terrestrial turtle named Proganochelys, at least 10 million years more recent than Odontochelys semistestacea.
The latest find therefore suggests that the evolution of turtles occurred in water.
Odontochelys is very different from the modern turtle because it had a long, pointed snout lined with teeth. All modern-day turtles have sharp beaks and no teeth. Further, in Odontochelys only the plastron (lower shell) was fully formed while the carapace (top shell) was not.
A picture of Odontochelysis given on the left to let you have an idea of how prehistoric turtles look like.
This post is part of Turtle Blogathon 2009, where we stayed up for 24-straight-hours to blog about turtles. To make a donation, please visit the Donations page. Posts written during the Turtle Blogathon are filed in the Turtle Blogathon 2009 category.
Similar Posts:

So the Archelon is not exactly the oldest turtles around???
Yeap, but for a long time, it was thought to be so
hehe…can’t imagine turtles having teeth now:)
Their beaks have been evolved into very effective cutting edges. Those of the leatherback are cusped and serve in holding its prey of jellyfish. I once had a pet softshell turtle (saved from being eaten by its captor) and it bit the frozen ikan kembung I gave it into 2! After that, i just threw the fish into the water :)
Thanks for answering. They look like baby lizards without the carapace!