Leatherback sea turtle and large size, leatherbacks are able to maintain high temperature differentials compared to the surrounding water. Adult leatherbacks have been found with core body temperatures that were above the water in which they were swimming. Leatherback turtles are one of the deepest-diving marine animals. Individuals have been recorded diving to depths as great as . Typical dive durations are between 3 and 8 minutes, with dives of 30–70 minutes occurring infrequently. They are also the fastest-moving reptiles. The 1992 edition of the "Guinness Book of World Records" lists the leatherback turtle moving at in the water. More typically, they swim
Varieties of Chinese their own standard languages. In China, however, Literary Chinese maintained its monopoly on formal writing until the start of the 20th century. The logographic writing, read with varying local pronunciations, continued to serve as a source of vocabulary and idioms for the local varieties. The new national standard, Vernacular Chinese, the written counterpart of spoken Standard Chinese, is also used as a literary form by speakers of all varieties. Dialectologist Jerry Norman estimated that there are hundreds of mutually unintelligible varieties of Chinese. These varieties form a dialect continuum, in which differences in speech generally become more pronounced as distances