The Chelydridae are a family of turtles that has seven extinct and two extant genera. The extant genera are the snapping turtles Chelydra and Macrochelys. Both are endemic to the Western Hemisphere. The extinct genera are Acherontemys, Chelydrops, Chelydropsis, Emarginachelys, Macrocephalochelys, Planiplastron, and Protochelydra.
- Kingdom: Animalia
- Phylum: Chordata
- Class: Reptilia
- Order: Testudines
- Suborder: Cryptodira
- Clade: Americhelydia
- Family: Chelydridae
The Chelydridae have a long fossil history, with extinct species reported from North America as well as all over Asia and Europe, far outside their present range. The earliest described chelydrid is Emarginachelys cretacea, known from well-preserved fossils from the Maastrichtian stage of the Late Cretaceous of Montana. Another well-preserved fossil chelydrid is the Late Paleocene Protochelydra zangerli from North Dakota.
The carapace of P. zangerli is higher domed than that of the recent Chelydra, a trait conjectured to be associated with the coexistence of large, chelonivorous crocodilians. Another genus, Chelydropsis, contains several well-known Eurasian chelydrid species that existed from the Oligocene to the Pliocene. In South America, chelydrids only occupy the northwestern corner of the continent, reflecting their recent arrival from Central America as part of the Great American Interchange.
These turtles are found in almost any kind of freshwater habitat within their range, but also occasionally enter brackish waters.
Snapping turtles enjoy a wide variety of food and are often considered the top predator in their environment. The alligator snapping turtle’s diet consists mainly of fish, which they lure using a pink worm-like appendage on the end of their tongue. Common snapping turtles are more active hunters and will eat just about anything.
They possess a vicious temperament and direct their powerful snapping jaws at both their food and their predators. Snapping turtles are highly aquatic, but do leave the water to nest, and one species migrates between bodies of water. They may be active at any time of day or night, but nocturnal activity is rare in northern populations. These turtles hibernate at temperate latitudes, but presumably are active year-round at more tropical sites.