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Topic: Evolution of cetaceans

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	Evolution of cetaceans - Wikipedia, the free encyclopedia
		The traditional theory of cetacean evolution was that whales were related to the mesonychids, an extinct order of carnivorous ungulates (hoofed animals), which looked rather like wolves with hooves and were a sister group of artiodactyls.
		The strong evidence for a clade combining cetaceans and artiodactyls is further discussed under the entry Cetartiodactyla.
		Whereas early cetaceans such as the Pakicetus had the nasal openings at the end of the snout, in later species such as the Rodhocetus, the openings had begun to drift toward the top of the skull.
	en.wikipedia.org /wiki/Evolution_of_cetaceans (1252 words)

	Britain.tv Wikipedia - Whales
		However, because cetacean brains function quite differently from the human brain, even if whales had matching body/brain weight ration to humans, it is not a conclusive indication of high intelligence.
		It is generally agreed that the growth of the neocortex, both absolutely and relative to the rest of the brain, during human evolution, has been responsible for the evolution of intelligence, however defined.
		Cetaceans, particularly dolphins, are highly social, and in addition they are generally friendly to humans.
	www.britain.tv /wikipedia.php?title=Whales (3272 words)

	ENHS Nature Trails January 2000 Article 2
		Cetaceans (whales, dolphins, and porpoises) are, for good reason, classified as mammals: like all mammals, cetaceans are air breathing, possess mammary glands, sweat glands and hair, give birth to live young, possess a four chambered heart, and have eggs that are fertilized internally.
		However, unlike their mammalian brethren, cetaceans are so completely adapted for aquatic life that they are unable to survive on land, a characteristic that distinguishes them from other mammals, even pinnapeds (seals, sea lions, and walruses) which live a significant part of their lives on land.
		The evolution of cetaceans from their land dwelling ancestors is a fascinating tale, rich in intermediate fossil forms spanning the transition from land to water.
	biology.uoregon.edu /enhs/archive/may00/may002.html (789 words)

	[No title] (Site not responding. Last check: 2007-11-06)
		The distribution and diversity of cetaceans found today is likely to be a result of global climatic changes as well as geologic changes.
		For example, it is likely that the global climate cooled during the beginning of the Oligocene, and this cooling may have limited the ability of some forms of early cetaceans (which originated in the warm waters of the Tethys Sea) to further colonise the worlds oceans.
		For example, while the squalodont cetaceans appear to have disappeared late in the Miocone, the kentriodonts persisted and may have culminated in the emergence of the first "modern" small odontocetes, including the dolphin family (Delphinidae), the river dolphin family (Platanistidae) and the porpoises (Phocoenidae)
	phocoena.org /evolution.html (535 words)

	Evolution (Stanford Encyclopedia of Philosophy)
		This coupling of evolution and natural selection theory, and the claimed competence of natural selection theory to explain both micro and macro evolution has, however, formed one of the most commonly debated issues in the history of evolutionary biology since Darwin.
		The evolution of the elaborate instincts of animals and the puzzling problem of the evolution of social instincts that resulted in the development of sterile neuter castes in the social insects proved to be a particularly difficult issue for Darwin in the manuscript phase of his work and needed some account (chp.
		In the eyes of philosophical critics of Fisherian-inspired interpretations of evolution, the substitution of organisms by genes in populations implies a false reductionism that incorrectly abolishes conceptions of organization, form, and purposeful behavior from evolutionary biology (Grene 1958, Grene and Depew 2004, chps.
	plato.stanford.edu /entries/evolution (17105 words)

	ADW: Cetacea: Information (via CobWeb/3.1 planetlab1.netlab.uky.edu) (Site not responding. Last check: 2007-11-06)
		Cetaceans are found in groups that range from single individuals (Inia geoffrensis), to small, unstable associations (many mysticetes) to herds of hundreds or even thousands of individuals (some odontocetes).
		Cetaceans are host to small parasites such as barnacles, which live on or in their skin, and copepods, such as Balaenophilus unisetus and Pennella, which live on their skin or in their blubber.
		Currently cetaceans are important for entertainment and tourist industries: captive odontocetes are trained to perform tricks for large crowds of spectators, and whale-watching boats are popular attractions for tourists wishing to catch a glimpse of cetaceans in the wild.
	animaldiversity.ummz.umich.edu.cob-web.org:8888 /chordata/mammalia/cetacea.html (3563 words)

	Cetacean Evolution (Site not responding. Last check: 2007-11-06)
		The common ancestor of cetaceans was actually a land animal that walked on four legs.
		Pakicetus is the earliest cetacean, and Ambulocetus arose shortly afterward.
		As a result of the adaptation to salt water, cetaceans were able to quickly disperse across the oceans and colonize the globe, which can be by modem day cetacean distribution.
	www1.pacific.edu /~e-buhals/cetacean.htm (2140 words)

	Cetaceans
		Some retained substantial hind limbs that would have been visible outside the animal's body; in the earliest archaeocetes, these limbs and the pelvis were attached to the vertebrae by a sacral joint, but in later ones the limbs and pelvis were not attached to the rest of the skeleton.
		By the late Oligocene, the two modern lineages of cetaceans had evolved from archaeocete ancestors.
		Shown at right is the partial skull of a porpoise from the Miocene-age Monterey Formation, exposed at Duxbury Reef in Marin County, northern California.
	www.ucmp.berkeley.edu /mammal/cetacea/cetacean.html (1271 words)

	Evolution -- Land-to-Sea Transitional Series
		Evolution works by modifying existing body plans to fit new conditions of life, and is often constrained by developmental pathways.
		Cetaceans have unique semicircular canals that allow them to be highly acrobatic swimmers without becoming dizzy.
		The research paper by Spoor F. et al., Vestibular Evidence for the Evolution of Aquatic Behaviour in early Cetaceans, Nature 417:163-166 (2002), is available here in.pdf format.
	members.aol.com /darwinpage/landtosea.htm (824 words)

	Evolution of Cetaceans Dolphins and Whales
		At first, the ancestors of cetaceans fed on molluscs and slow fish, but as the population grew and competition for resources increased, there was a need for the development of fast reflexes and teeth suitable for catching fast fish.
		Since evolution usually occurs in unfavorable conditions where the size of the popluation is reduced, it was particularly accelerated during this period.
		The evolution was very aggressive, with many adaptations for survival, including resistance to the accumulation of hemoglobin, tolerance of low levels of oxygen, a hypodermal blubber layer for the storage of nutrients, sophisticated control of the body temperature, and telescoping of the front of the skull.
	www.robins-island.org /dolphins_evolution.php (2234 words)

	Learn with Us >>> Dolphins & Whales
		But the more correct classification distinguishes between cetaceans with teeth -odontoceti- and without teeth-mysticeti-, as, although one tends to consider the sperm whale (cachalot) as a whale, for example, it is much more closely related to dolphins.
		It is possible that the two groups of cetaceans have different origins.
		In the next lesson we shall see in a graphic and very educational manner an evolutionary outline of cetaceans, differentiating their families and sub-families.
	www.mundomar.es /gbmundomar/spaprende005.asp (99 words)

	Biozone: Evolution
		A general site on evolution that covers: systematics, dinosaur discoveries, vertebrate flight, and a thorough coverage of important people whose ideas influenced the development of evolutionary theory.
		Examination of the evolution of Cetaceans from land mammal to marine.
		Cetaceans evolved rapidly, and the entire transition from land mammal to obligate marine whale took less than 8 million years.
	www.biozone.co.nz /EVOLUTION.html (969 words)

	Cetacea (via CobWeb/3.1 planetlab1.netlab.uky.edu) (Site not responding. Last check: 2007-11-06)
		Cetology is the branch of marine science accociated with the study of cetaceans.
		Cetaceans are nearly hairless, and are insulated by a thick layer of blubber.
		Cetaceans are descendants of land-living mammals, most likely of the Artiodactyl order.
	cetacea.kiwiki.homeip.net.cob-web.org:8888 (456 words)

	The Evolution of Whales, Adapted from National Geographic, November 2001
		Cetaceans are divided into two groups, the Mysticetes (baleen whales) which use comblike plates on the roofs of their mouths to strain food from the water.
		Cetaceans (whales, dolphins and porpoises) have unique semicircular canals that allow them to be highly acrobatic swimmers without becoming dizzy.
		Barnes reminded the author, the evolution of cetaceans was not only about bigness, sharing a dolphin skull and pointing out how the bones of the snout extend over the brain case.
	www.edwardtbabinski.us /whales/evolution_of_whales (10783 words)

	ACS - American Cetacean Society
		Cetacean evolution is continually being examined and altered according to new findings.
		Basically, this means that the closest ancestor to the cetaceans is a predecessor of the modern hippo.
		However, Theweissen believes that cetaceans and artiodactyls are two branches of a larger group, or clade, called the cetariodactyls.
	www.acsonline.org /issues/researchRpts/Research0203.html (725 words)

	The Origin of Whales and the Power of Independent Evidence (via CobWeb/3.1 planetlab1.netlab.uky.edu) (Site not responding. Last check: 2007-11-06)
		Additionally, the joint between the malleus (hammer) and incus of most mammals is oriented at an angle between the middle and the front of the animal (rostromedially), while in modern whales and in ungulates, it is oriented at an angle between the side and the front (rostrolaterally).
		The biogeographic distribution of fossil whales matches the pattern predicted by evolution: whales are initially found in a rather small geographic area and did not become distributed throughout the world until after they evolved into fully aquatic animals that were no longer tied to the land.
		Evolution predicts that whales could not have successfully appeared and radiated before the Eocene, and that mammals should have radiated into marine environments as they did into a wide variety of other environments vacated by the reptiles at the end of the Cretaceous.
	www.talkorigins.org.cob-web.org:8888 /features/whales (6400 words)

	CETACEAN EVOLUTION - Dolphins and Whales Window
		Modern cetaceans are fully aquatic mammals that have no hind limbs, flippers for forelimbs, and fusiform bodies, among other traits.
		These cetaceans often have teeth that are simple pegs (or other forms that are nevertheless highly modified from early mammal teeth).
		This feature is only found in modern mammals that have a tail fluke (cetaceans and sirenians) and the pattern of shape change along the vertebral columns of dorudontines is very similar to the pattern seen in modern cetaceans.
	dolphins.jump-gate.com /start_page/cetacean_evolution.shtml (784 words)

	- Overselling of Whale Evolution -
		One committed to evolution would tend to be less critical of dates that placed these fossils in a morphological sequence and more critical of dates that disrupted that sequence.
		There are major differences between the archaeocetes and cetaceans (e.g., body shape, thoracic fin structure, and skull arrangement) which have led many experts to deny that archaeocetes gave rise to odontocetes or mysticetes.
		Banister and Campbell likewise remark, “The origins of present-day cetaceans are poorly known.” Banister and Campbell, 294.
	www.trueorigin.org /whales.asp (3394 words)

	Evolution, Science and Society: An Example of the Uses of Biodiversity Knowledge
		Whales and dolphins (cetaceans) are definitely mammals: they are warm-blooded, they suckle their young, they have three bones in the middle ear.
		Exactly how cetaceans are related to other mammals, however, has been elucidated out only since the 1960s, through a combination of good phylogenetic analysis and spectacular paleontological discoveries.
		In the later evolution of the cetaceans, these hindlimbs became further reduced, losing the toes and kneecap needed for terrestrial locomotion.
	evonet.sdsc.edu /evoscisociety/transitions_from_fossil_rcrd.htm (414 words)

	Whales Resource Page - map of wales
		The baleen whales are characterized by the baleen, a sieve-like structure in the upper jaw made of keratin, which they use to filter plankton from the water.
		Many people believe that cetaceans in general, and whales in particular, are highly intelligent animals.
		It new south wales is generally agreed that the growth of the neocortex, both absolutely and relative to the rest of the brain, during human evolution, has been responsible for the evolution of intelligence, however defined.
	www.governpub.com /gt/Whales.html (2598 words)

	SPACE.com -- The Evolution of Intelligence: An Integral Part of SETI and Astrobiology
		Our understanding of the evolution of intelligence has been based on the common presumption that increased intelligence has been actively selected for over evolutionary time.
		Cetaceans are highly encephalized, possessing EQs that range very close to that of humans and higher than that of other mammals.
		Therefore, cetaceans afford us the opportunity to examine a highly elaborated brain that has taken a very different evolutionary trajectory from our own.
	www.space.com /searchforlife/seti_intelligence_030821.html (1027 words)

	American Cetacean Society
		We contend that we will not be able to fully understand the past and ongoing evolution of cetaceans without considering the cultural aspects of their lives, and that such consideration also has implications for management and conservation.
		With respect to evolution: cultural differences may have been the starting point for the on-going speciation of 'resident' and 'transident' killer whales, gene-culture co-evolution may be behind low levels of genetic diversity in some species, and extended post-menopausal life spans in killer and pilot whales may be explained by the information value of grandmothers.
		With respect to management, understanding how cetacean populations adapt, culturally or otherwise, to changing environments is of critical importance and will inform attempts to rehabilitate captive animals, respond to mass strandings, and manage human interactions with cetaceans through fishing and tourism.
	www.acsonline.org /conference/culture2002/speakers/rendell.html (345 words)

	Creationist Mindblocks to Whale Evolution: Part 2
		As you may have guessed, not only does this paper have nothing to do with cetacean evolution, but the problems addressed in ascertaining molecular phylogenies are, as stated, different than those of determining relationships of more recently diverged taxa.
		Clearly, there are several aspects of the origin and evolution of cetaceans that are in need of more evidence and clarification, from the fossil record, and physiological and molecular research.
		Thewissen, J.G.M. (1998) Cetacean Origins: Evolutionary Turmoil During the Invasion of the Oceans: in The Emergence of Whales, edited by Thewissen.
	www.angelfire.com /fl/direpuppy/mindblock2.html (1556 words)

	Natural History Museum: Research & Collections: History
		The Natural History Museum has been actively studying stranded cetaceans since 1960 and has assembled a research collection of marine mammals that is second in size only to that of the Smithsonian Institution.
		Since it is difficult to fully observe cetaceans at sea, photographs and measurements of stranded animals provide us with details of the size, shape, and true color pattern of particular species.
		Anyone who finds a dead cetacean on the beach in Los Angeles and Orange Counties should contact the Natural History Museum's Stranding Hotline at (323) 585-5105, or the curator of marine mammals, Dr. John Heyning at (323) 763-3367.
	www.nhm.org /research/mammals/stranding/index.html (519 words)

	studyguide
		Starting at the K-T Boundary, construct a timeline listing the major events in the evolution of marine mammals, including times and locations for the evolution of cetaceans, sirenians, pinnipeds, sea otters, polar bears, and the only extinct order of marine mammals (don’t forget to give me the name of that order).
		Without having to memorize all the opposing scenarios, you should understand cladograms enough that if I ask you to draw a cladogram depicting a specific relationship (for example, demonstrating that of the 3 pinniped families, odobenids are monophyletic with phocids only), you are able to do it.
		List and describe the important "players" discussed in class that fall along the evolutionary line of cetaceans, from the early terrestrial ancestors (broad group and potential specific group) to the rise of the 2 extant sub-orders, to modern cetaceans.
	kingfish.coastal.edu /marine/375/studyguide.htm (2239 words)

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