Articles
Evolution
Facts
Nesting
Sea Turtle Evolution
Turtles as a group are believed to have first appeared on earth about 200 million years ago. They were quite common 130 million years ago and lived at the same time as the dinosaurs. All turtles are believed to have evolved from the cotylosaurs, a group of early reptiles from which not only all living reptiles, but even mammals and birds, evolved. Turtles have not changed much in a long, long, time. For instance, the turtle of the Triassic period (175,000,000 years ago) already had the same fundamental characteristics as the turtles we see today. The earliest sea turtle fossils date back about 150, 000, 000 years, to a time when vast and shallow seas covered the earth.
One of the sea turtles, the Archelon, had a 12 foot (3.7 m shell), and lived 70 million years ago. It was the size of a small car! The Archelon had a leathery shell, much like the leatherback of today (the largest sea turtle). Of course, the archelon is no more, but his ancestors are roaming the seas now. There are more than 250 different turtle species living today. All of them enjoy the benefit of a bony shell that encloses their vital organs. The shells of some turtles are so strong that they can endure the weight of a 200 pound man without damage.
Now, sea turtles differ from other turtle species in many ways. Firstly, they are not able to withdraw into their shells. Their shells are also more streamlined and less box like. Unlike tortoises, Sea turtles are able to move with extreme quickness in water. In their environment, they are capable of tremendous burst of speeds that human swimmers envy. Green Sea Turtles are said to swim at a rate of 30 feet a second!Sea turtles have lived for a remarkably long time! Compare their period on earth (150 million years) with that of humankind ( 5 million years)! Sea turtles have also survived tough odds. They managed to survive the event that caused the dinosaurs to become extinct 65 million years ago. They even survived the intense cold of the ice ages that gripped the planet for much of the past 3 million years.
