There are many turtles that have a movable hinge on the plasteron, but the Hinge-Back Tortoise (genus - Kinixys) is the only living turtle where the hinge has developed across the back of the carapace. This broad band of flexible connective tissue is located between the 4th and 5th costals and the 7th and 8th peripherals in adults.
Hatchlings of this African tortoise are flattened with serrated marginals. The hinge begins to develop when they are one year old.
This movable hinge provides protection by closing off the tortoise's hind legs and tail and it may also assist in egg laying and respiration.
Hinge-Backs have legs that are not as club shaped as other Testudinidae. They are long and slender giving the tortoise an unusual gait when it walks. Hinge-Backs are all omniverous and their tails end in a claw like tubercle. Males have longer, thicker tails than the females and they have concave plasterons. Hinge-Back Tortoises have relatively long skulls, a hooked upper jaw and four or five claws on each forefoot.
Different species of Hinge-Back Tortoises are found in Africa.
Kinixys belliana (Bell's Hinge-Back Tortoise) is the most widely distributed and best known of the species of Hinge-Backs.
This Hinge-Back's carapace is domed with a flat dorsal surface and sloping sides. It's anterior and posterior marginals are not flared. The center of each carapacial scute is yellow to reddish brown, surrounded by dark brown or black. The plasteron is yellow with black radiation. Its head is brown, black, yellow or tan and the limbs and tail are grayish brown.
Four subspecies of Kinixys Belliana are recognized:
Kinixys belliana belliana is found in eastern Africa from Somalia to South Africa. Kinixys belliana spekii lives in southern and central Africa and Kinixys belliana mertensi lives in northern Zaire and Uganda. Kinixys belliana nogueyi is found in west Africa and unlike the other 3 sub-species who have 5 claws on each forefoot, it has only 4.
Prefers savannas, dry brush, and grasslands. Occurs from Somalia southward to Swaziland and Natal and westward into Zaire and across West Africa to Senegal.
It prefers the dry savannas and grasslands that skirt Africa's rainforests, where there are distinct wet and dry seasons. They become active with the onset of rains and probably lay eggs at this time.
During dry periods it estivates in the muddy bottoms of drying water holes.
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