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The adaptation of echolocation and enhanced fat synthesis in blubber occurred when toothed whales split apart from baleen whales, and distinguishes modern toothed whales from fully aquatic archaeocetes. This happened around 34 mya. [9] Unlike toothed whales, baleen whales do not have wax ester deposits nor branched fatty chain acids in their ...
Baleen whales split from toothed whales (Odontoceti) around 34 million years ago. Baleen whales range in size from the 6 m (20 ft) and 3,000 kg (6,600 lb) pygmy right whale to the 31 m (102 ft) and 190 t (210 short tons) blue whale, the largest known animal to have ever existed. [1] [2] They are sexually dimorphic.
The family Balaenidae, the right whales, contains two genera and four species. All right whales have no ventral grooves; a distinctive head shape with a strongly arched, narrow rostrum, bowed lower jaw; lower lips that enfold the sides and front of the rostrum; and long, narrow, elastic baleen plates (up to nine times longer than wide) with fine baleen fringes.
The adaptation of animal echolocation in toothed whales distinguishes them from fully aquatic archaeocetes and early baleen whales. The presence of baleen in baleen whales occurred gradually, with earlier varieties having very little baleen, and their size is linked to baleen dependence (and subsequent increase in filter feeding).
Bowhead whale plates can be 9 metres (30 ft) long. Their nostril(s) make up the blowhole, with one in toothed whales and two in baleen whales. [21] The nostrils are located on top of the head above the eyes so that the rest of the body can remain submerged while surfacing for air. The back of the skull is significantly shortened and deformed.
That means baleen whales make their sounds with their larynx, as do humans, while toothed whales - including dolphins, porpoises, killer whales and sperm whales - evolved a different mechanism ...
The larger parvorder, Mysticeti (baleen whales), is characterized by the presence of baleen, a sieve-like structure in the upper jaw made of keratin, which it uses to filter plankton, among others, from the water. Odontocetes (toothed whales) are characterized by bearing sharp teeth for hunting, as opposed to their counterparts' baleen. [10]
According to the DOC, the spade-toothed whale was first documented in 1874 from lower jaw and teeth samples collected on Pitt Island, around 500 miles off New Zealand’s west coast. Other ...