Leatherback sea turtle million years ago during the Cretaceous period. The dermochelyids are relatives of the family Cheloniidae, which contains the other six extant sea turtle species. However, their sister taxon is the extinct family Protostegidae that included other species that did not have a hard carapace. Leatherback turtles have the most hydrodynamic body design of any sea turtle, with a large, teardrop-shaped body. A large pair of front flippers powers the turtles through the water. Like other sea turtles, the leatherback has flattened forelimbs adapted for swimming in the open ocean. Claws are absent from both pairs of flippers. The leatherback's flippers
Varieties of Arabic sedentary varieties and the rural varieties within the Arabian peninsula are even more conservative than those elsewhere. Within the sedentary varieties, the western varieties (particularly, Moroccan Arabic) are less conservative than the eastern varieties. A number of cities in the Arabic world speak a "Bedouin" variety, which acquires prestige in that context. When it comes to phonetics the Arabic dialects differ in the pronunciation of the short vowels (, and ) and a number of selected consonants, mainly , and the interdental consonants , and , in addition to the dental . Emphasis spreading is a phenomenon where is backed