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Cryptodires
The Cryptodira ('' el, hidden neck'') are a suborder of Testudines that includes most living tortoises and turtles. Cryptodira differ from Pleurodira (side-necked turtles) in that they lower their necks and pull the heads straight back into the shells, instead of folding their necks sideways along the body under the shells' marginals. They include among their species freshwater turtles, snapping turtles, tortoises, softshell turtles, and sea turtles. Neck retraction The Cryptodira are characterized by retraction of the head in the vertical plane, which permits for primarily vertical movements and restricted lateral movements outside of the shell. These motions are largely due to the morphology and arrangement of cervical vertebrae. In all recent turtles, the cervical column consists of nine joints and eight vertebrae. Compared to the narrow vertebrae and the closely positioned zygapophyses of the pleurodires, the cryptodires’ vertebrae take on the opposite shape. Their cervic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aldabra Giant Tortoise
The Aldabra giant tortoise (''Aldabrachelys gigantea'') is a species of tortoise in the family Testudinidae. The species is endemic to the islands of the Aldabra Atoll in the Seychelles. It is one of the largest tortoises in the world.Pritchard, Peter C.H. (1979) ''Encyclopedia of Turtles.'' Neptune, New Jersey: T.F.H. Publications, Inc. Ltd. Historically, giant tortoises were found on many of the western Indian Ocean islands, as well as Madagascar, and the fossil record indicates giant tortoises once occurred on every continent and many islands with the exception of Australia and Antarctica. Many of the Indian Ocean species were thought to be driven to extinction by over-exploitation by European sailors, and they were all seemingly extinct by 1840 with the exception of the Aldabran giant tortoise on the island atoll of Aldabra. Although some remnant individuals of ''A. g. hololissa'' and ''A. g. arnoldi'' may remain in captivity, in recent times, these have all been reduced a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
