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
Spanish dialects and varieties which is the preferred form in formal settings, and is considered indispensable in academic and literary writing, the media, etc. This standard tends to disregard local grammatical, phonetic and lexical peculiarities, and draws certain extra features from the commonly acknowledged canon, preserving (for example) certain verb tenses considered "bookish" or archaic in most other dialects. Spanish dialects and varieties Some of the regional varieties of the Spanish language are quite divergent from one another, especially in pronunciation and vocabulary, and less so in grammar. While all Spanish dialects adhere to approximately the same written standard, all spoken varieties differ from