Thanks to good fossil records, we know that turtles are some of the oldest vertebrates on Earth. They made their appearance during the late Triassic period, about 250 million years ago. They are part of the reptile family that includes crocodilians (alligators and crocodiles), who are their closest relatives, the dinosaurs, who they lived alongside, and birds.
You read that correctly. Current studies show that genetically, birds are most closely related to crocodiles, turtles, and dinosaurs. But you have always suspected your Mr. Tweetie was hiding something, haven’t you?
You might look at sea turtles and assume turtles have always been aquatic, but the earliest turtles lived on land. At first, they had expanded ribs, not the fully formed shell we associate with turtles today. The early turtles include:
- Eunotosaurus africanus, 260 million years ago. Eunotosaurus looked like a modern-day lizard but had wide, flat ribs that rounded the torso into the shape of a turtle shell. Eunotosaurus fossils were found in southern Africa.
- Pappochelys rosinae, 240 million years ago. Found in Germany, the fossils are like Eunotosaurus with wide, flat ribs.
- Odontochelys semitestacea, 220 million years ago. Until Eunotosaurus and Pappochelys were discovered, Odontochelys, whose fossil was found in China, was thought to be the original turtle. While still lacking the carapace (upper shell), Odontochelys had a fully formed plastron (lower shell) and are believed to have spent at least part of the time in shallow water, the earliest evidence of turtles becoming aquatic.
- Proganochelys quenstedti, 220 million years ago. Fossils indicate Proganochelys was the first “true turtle,” in that it had a fully formed carapace as well as a plastron. Proganochelys was believed to be only semi-aquatic and an herbivore, so more like a tortoise than today’s aquatic turtles. The shell of Proganochelys was about three feet long and it had a long tail, reminiscent of snapping turtles.
- Meiolania, 20 million years ago. There are three distinct species in the genus Meiolania, and these are almost present-day tortoises, except for their horns and clubbed tails. They are the largest tortoises that have ever existed, with a carapace length over six feet. Most Meiolania fossils have been found in Australia and nearby South Pacific islands. Unfortunately, there is evidence Meiolania disappeared shortly after the arrival of humans, which may make them one of the first instances of human-caused extinction.
- Stupendemys, 10 million years ago. Fossils found in South America tell us Stupendemys had a carapace exceeding six feet in length, and sometimes as long as ten feet, making it the largest freshwater turtle ever to have existed.
- Hesperotestudo, 2 million years ago. Fossils of these giant tortoises are found mainly in North America and are like present-day gopher tortoises. Hesperotestudo existed alongside humans who hunted them for food, which most likely led to their extinction.
In the 250 million years that turtles have been on Earth, they have never been in as much danger of extinction as they are today. We hope that as you learn more about ancient turtles, you will also learn how to help turtles today.
Dancing Turtle’s education programs include fascinating facts about the earliest turtles to inspire conservation.