Cetacea

Cetacea: An Order of marine mammals. The suborder Odontocetti includes dolphins, killer whales and toothed whales. Many of the great whales (such as the blue whale) belong to a different suborder (baleen whales or Mysticetti).

Cetaceans include toothed whales (Suborder Odontoceti), such as the Sperm Whale, dolphins, and porpoises. Cetaceans also include baleen whales (Suborder Mysticeti), such as Gray Whales, Humpback Whales, and Blue Whales.

cetaceans (order Cetacea)Marine mammals with anterior flippers, no posterior limbs, and a dorsal fin: whales, dolphins, and porpoises.
chaetognaths See arrow worms.

Cetacea
whales, dolphins, porpoises
Afrotheria
The 5 orders shown in yellow are found in Africa. They appear to be the most primitive of the placental mammals.
Xenarthra ...

Current cetacea (whales), as you are no doubt aware, do not have external hind limbs. But whales, which are mammals, evolved from terrestrial mammals. This fossil, therefore, is a link between the two.

The sense of smell is less-developed in the catarrhine primates (Catarrhini), and nonexistent in cetaceans, which compensate with a well-developed sense of taste. In some prosimians, such as the Red-bellied Lemur, scent glands occur atop the head.

A group called cetaceans includes dolphins and whales. They are mammals that evolved and returned to the ocean. They still breathe air and even have tiny hairs like other mammals, but they live their whole lives in the water.

Cladogram
An example of a cladogram, which depicts the relatedness of taxonomic groups; uses the order Cetacea, whales, as an example.
View Animation Still ...

Classification is based on the mode of locomotion and methods of obtaining food. Prominent orders include the bats (order Chiroptera), horses (order Perissodactyla), whales (order Cetacea), mice (order Rodentia), dogs (order Carnivora), ...

or wanting, and the front ones are changed to paddles. They have horny plates on the front part of the jaws, and usually flat-crowned molar teeth. The stomach is complex and the intestine long, as in other herbivorous mammals. See cetacea .

See also: Animal, Species, Animals, Trans, Mammals