Evol. The isolation mechanism is less complete in mysticetes, but the large distance between the two ears (simply because of the size of these animals) probably helps directional detection. ), The Emergence of Whales: Evolutionary Patterns in the Origin of Cetacea , Plenum, New York.Gatesy, J. , C. Hayashi , M. Cronin, and P. Arctander. The phylogeny of the unglates. 1996. 1999. Sci. The cetacean evolution of both suborders are incredibly similar, as they are all a result of evolutionary convergence. Mammalian Phylogeny: Comparison of Morphological and Molecular Results.
Evol. 201-234. Tracing characteristics of living cetaceans back through geological time enables us to identify traits that are primitive in Cetacea and, hence, to recognize the origin of the order and its broader phylo-genetic relationships. Phylogenetic Relationships of Artiodactyls and Cetaceans as Deduced from the Comparison of Cytochrome b and 12s rRNA Mitochondrial Sequences. Evolution of the cytochrome b gene of mammals. Phylogeny of all major groups of cetaceans based on DNA sequences from three mitochondrial genes.
American Museum Novitates 677: 1-18.Rice, D. W. 1998.
Gregory.
Relative likelihoods of various hy- Evol. Marine mammals of the world. 2003. J. Mammal. Hind limbs of Eocene Basilosaurus: evidence of feet in whales. Mol. J Evol Biol, 5:149-160.Milinkovitch, M. C. 1995. However, based on the comparison between the facial anatomy of dwarf and pygmy sperm whales, Heyning (1989) suggested the junk (a segmented tissue located below the spermaceti case and so-called because it is less rich in oil than the spermaceti itself) rather than the spermaceti organ as the most likely candidate.
Comparative facial anatomy of beaked whales (Ziphidae) and a systematic revision among the families of extant Odontoceti. They can also tell the direction of sound underwater.Whales have collapsible rib cages and flexible skeletons, which allows them to compensate for high water pressure when they dive. Higgins. Evol.
This ancestor diversified over time into several descendent subgroups, which are represented as internal nodes and terminal taxa to the right.You can click on the root to travel down the Tree of Life all the way to the root of all Life, and you can click on the names of descendent subgroups to travel up the Tree of Life all the way to individual species.For more information on ToL tree formatting, please see,Cetaceans (whales, dolphins and porpoises) form one of the most dramatically-derived group of mammals.
Bulletin du Muséum National d'Histoire Naturelle, Paris 4 C, (3-4): 279-326.Nikaido M., A.P. Mol. Evol.
It is unclear whether mysticetes are able to rely on the echoes of their low-frequency sounds.Dorsal and anterior to the skull, sperm whales also have a large oily organ (called the “spermaceti organ” because early whalers thought the whitish oily substance was the whale semen) that possibly works as a biological ballast (Raven & Gregory 1933; Clarke 1970) or constitutes a secondary sexual character involved in acoustic display (Cranford 1999). Analyses of neontological data have long suggested that cetaceans are closely related to ungulates (,The two main alternative hypotheses regarding the exact phylogenetic position of cetaceans within mammals are suggested respectively by morphological and molecular data. Nat. 1999. and J.H. General Characteristics. Function of the spermaceti organ of the sperm whale. Phylogenetic aspects of cetacean origins: a morphological perspective. Morphological evidence for the phylogeny of Cetacea. Some cetaceans, such as the Dall's porpoise and the orca (killer whale) can swim faster than 30 miles per hour.When a cetacean wants to breathe, it has to rise to the water surface and exhale and inhale out of the blowholes located on top of its head.
This blubber layer can be as much as 24 inches thick in some whales.Whales have a poor sense of smell, and depending on where they are, they may not be able to see well underwater. 2005. Eventoed Fingerprints on Whale Ancestry. The telescoping of the skull mostly involves the posterior extension of the bones of the elongated rostrum: maxillae, premaxillae, vomer and mesethmoid;Isolation of the earbones related to the development of underwater hearing and echolocation abilities.
Journal of Mammalian Evolution 10(1-2):23-129.Gingerich, P. D., B. H. Smith, and E. L. Simons.
Rooney,and N. Okada. They even have hair.