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Species of the infraorder Cetacea A phylogenetic tree showing the relationships among cetacean families. [1]The evolution of cetaceans is thought to have begun in the Indian subcontinent from even-toed ungulates (Artiodactyla) 50 million years ago (mya) and to have proceeded over a period of at least 15 million years. [2]
The following is a list of currently existing (or, in the jargon of taxonomy) 'extant' species of the infraorder cetacea (for extinct cetacean species, see the list of extinct cetaceans). The list is organized taxonomically into parvorders, superfamilies when applicable, families, subfamilies when applicable, genus, and then species.
The fin whale (Balaenoptera physalus), also known as the finback whale or common rorqual, is a species of baleen whale and the second-longest cetacean after the blue whale. The biggest individual reportedly measured 26 m (85 ft) in length, with a maximum recorded weight of 77 to 81 tonnes (85 to 89 short tons; 76 to 80 long tons).
The general idea of reconciliation is that a phylogenetic tree representing the evolution of an entity (e.g. homologous genes or symbionts) can be drawn within another phylogenetic tree representing an encompassing entity (respectively, species, hosts) to reveal their interdependence and the evolutionary events that have marked their shared ...
The most widely used test for self-awareness in animals is the mirror test, in which a temporary dye is placed on an animal's body and the animal is then presented with a mirror. Researchers then explore whether the animal shows signs of self-recognition. [64] Critics claim that the results of these tests are susceptible to the Clever Hans effect.
This puts mesonychians as a distant relative of cetaceans rather than an ancestor, and their somewhat similar morphology was possibly a result of convergent evolution. The oldest known cetacean is the ambulocetid Himalayacetus identified in 1998 and dated to 52.5 million years ago (predating the terrestrial pakicetids), though the exact dating ...
The traditional theory of cetacean evolution was that cetaceans were related to the mesonychian. These animals had unusual triangular teeth very similar to those of primitive cetaceans. This is why scientists long believed that cetaceans evolved from a form of mesonychian.
In evolution, it can scramble the information needed to reconstruct the phylogeny of organisms, how they are related to one another. HGT can also help scientists to reconstruct and date the tree of life, as a gene transfer can be used as a phylogenetic marker, or as the proof of contemporaneity of the donor and recipient organisms, and as a ...