Loggerhead sea turtle turtle is debated, but most authors consider it a single polymorphic species. Molecular genetics has confirmed hybridization of the loggerhead sea turtle with the Kemp's ridley sea turtle, hawksbill sea turtle, and green sea turtles. The extent of natural hybridization is not yet determined; however, second-generation hybrids have been reported, suggesting some hybrids are fertile. Although evidence is lacking, modern sea turtles probably descended from a single common ancestor during the Cretaceous period. Like all other sea turtles except the leatherback, loggerheads are members of the ancient family Cheloniidae, and appeared about 40 million years ago. Of the six species
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