The first turtles evolved about 200 million years ago, long before the dinosaurs.
All turtles lay eggs. When egg-laying time comes, the mother typically digs a hole, lays her hard-shelled eggs in it, then fills the hole with earth, and leaves. After an incubation period, which may be as short as 6 weeks or more than 7 months, the hatchlings must dig their way to the surface.
If you go turtle watching at a park or reserve, be sure to take along binoculars or, even better, a telescope, so you can identify what you see. Turtle identification at a distance can be hard, especially since the field marks separating many species are details of color and design of the shell, which may be covered with moss or mud. The National Audubon Society Field Guide to North American Reptile and Amphibians reports that worldwide there are 12 families of turtles, of which 7 are represented in North America. North of Mexico, we have 48 species to look for.
Several of these 48 species are found only in the Deep South or in the western deserts. If you live elsewhere the number of turtles possibly seen in your region should be low enough for you to quickly learn to recognize each species.
In most of the eastern and central U.S., if a high-backed turtle from a nearby natural or semi-natural area wanders into your dry backyard, it'll probably be a box turtle of the genus Terrapene, one of which is shown in the next section, under the heading "Tortoise.". It'll be the Eastern Box Turtle, Terrapene carolina carolina. You'll see in your field guide that there is also a Western species of box turtle, and that both the Eastern and the Western species are separated into different-looking subspecies.
Let's clarify these three terms:
So, what's the "turtle" at the top of this page? Most books call it a slider but most average people call it a Red-eared Turtle. It looks a little like a terrapin and it also slides from logs into the water when you get near, plus it's hard-shelled, edible and aquatic. However it's not Malaclemys terrapin and, since Red-eared Turtles were originally mostly a Southeastern species and the Algonquian Indians who provided the name terrapin are northeastern and probably didn't know about this species, you might not want to call it a terrapin. Really, "slider" is just as important as a name as "terrapin," but for some reason most people in most places gravitate toward "terrapin," not "slider."
Whatever the situation, it should be clear by now that these terms are a little vague and flexible, as well as confused and confusing. At least in a general way, they're all turtles...
NORTH AMERICAN FAMILIES
OF INLAND TURTLES
To see a much more complete, and
confusing, breakdown, visit the
NCBI taxonomy database page for turtles
It's always a temptation to capture turtles for pets. If you spot one, it's best to leave it alone or, if it appears to be headed for disaster as by crossing a busy highway, it should be carried back to its park or reserve. Box turtles usually withdraw into their box if approached, so picking them up is easy. However, they do have long necks so they can quickly twist around their heads and bite very hard. If a child absolutely must watch a turtle in captivity for a day or two, box turtles eat slugs, earthworms, strawberries, mushrooms and, in a pinch, white bread mashed into lumps. White bread is so low in nutrition, however, that it shouldn't be fed for long.
The next time you see a turtle, take the time to admire its beautiful adaptations. Naturally their most interesting adaptation is its shell. The turtle's top shell is known as the carapace, while the bottom shell is the plastron. That's a plasteron at the right. If you ever find a carapace lying on the ground, where the rest of the turtle has rotted away, you'll see how the turtle's backbone runs down the middle of the carapace's inner face. This shows that the shell is basically the turtle's enlarged and fused-together ribs. One curious thing about turtles is that they don't have teeth, which other reptiles do. Instead, they possess an almost bird-like horny beak. (Birds evolved from reptiles so this isn't surprising!)
Turtle design, compared to that of other reptiles, is so bizarre that paleontologists have a hard time figuring out how they evolved and where they came from. It's easier to explain how birds arose from reptiles than how turtles appeared among their fellow reptiles!
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