The first known turtles appeared on Earth in the late Triassic Period - this is
around 200 million years ago, so they are older than many of the well known great dinosaurs!
One of the oldest fossilized turtles is Proganochelys . It looked like a modern turtle, with a fully developed shell, but it had small teeth and ears.
In the middle Jurassic Period the primitive Triassic turtles evolved into two main groups:
side-necked turtles and arch-necked turtles . Unlike Proganochelys, they were able to withdraw their heads into their shells in two different ways.
The side-necked turtles retracted their heads sideways, while the arch-necked turtles
folded their necks in an S-like shape. Most of the modern turtles and tortoises belong
to the arch-necked group, but the largest known fresh-water turtle, Stupendemys geographicus ,
belonged to the side-necked family. This giant was 8 feet ( 2.4 meters ) and lived in the rivers of the South America until quite recently - about ten thousend years ago.
The first sea turtles appeared during the late Jurassic Era - about 65 million years ago, and during the following
Cretaceous Period. The largest ever to exist turtle on Earth, Archelon ischyros, had a body 9.5 to 13 feet long ( 3 -4 meters ).
All of our modern sea turtles swam along with this giant.
Photo: Archelon ischyros - reconstruction based on the casts of the bones found in South Dakota. It could have been 20 feet wide from one flipper tip to the other, and
lived about 70 million years ago. Image courtesy of the Euro Turtle
Since Jurassic times turtles have evolved into more than 250 species, including about 180 species of freshwater turtles, 60 species of tortoises, and 8 species of sea turtles, with new species still being discovered. Many species are plentiful thanks to the conservation efforts of various countries, however, some are on the verge of extinction due to human exploitation for a large variety of turtle products. Sadly, the number of turtle species might decrease for the first time since they lived with dinosaurs.
C.I.T.I.E.S. is an organization enforcing animal and plant protection laws. Protected turtles include all of the sea turtles, the Galapagos giant tortoises, the radiated tortoise ( Geochelone radiata ) and until recently one of the snapping turtle family members - the alligator snapping turtle Macroclemys Temmincki.