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 Chinese dialect of northern Fujian is a minimal example. With the exception of , which is often merged with the zero initial, the initials of this dialect are present in all Chinese varieties, although several varieties do not distinguish from . However, most varieties have additional initials, due to a combination of innovations and retention of distinctions from Middle Chinese: Chinese finals may be analysed as an optional medial glide, a main vowel and an optional coda. Conservative vowel systems, such as those of Gan dialects, have high vowels , and , which also function as medials, mid vowels and ,