Evolution of Whales
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Transcript of Evolution of Whales
Evolution Of Whales
Sanjana SureshFSLE-3
Kingdom :Animalia ; Phylum : Chordata ; Subphylum: Vertebrata ; Class : Mammalia ; Order: Cetacea
Cetaceans include whales, dolphins, tortoises and porpoises There are over 80 Species in two Suborders :Mysticeti and
Odontoceti
Modern Whales
Mysticeti Odontoceti
Blue Whale Bowhead Whale (Arctic Region) Gray Whale Humpback Whale North Atlantic Right Whale Sperm Whale Beluga Orca (Killer Whale)
Whale Species
1693- John Ray, whales are mammals
1859- Darwin, in Origin of Species, whales arose from bears
1883- Sir William Henry Flower, solidifies theory of descendants were from terrestrial mammals based on vestigial organs
Early History of Whale Evolution
Thewissen discovers fossil dated to 60 million years ago in Kashmir region of India
Even toed ungulate, a form of the mammalian order Artiodactyla
Marine lifestyle
Indohyus
First Archaeocete
Evolved 52 million years ago Found in Pakistan by Gingerich,
1983
Sharper teeth-more carnivorous
Deficient in hearing underwater, more terrestrial hearer-not yet evolved
Narrow brain case
Pakicetus
Ambulocetus Natans
Found in sediments about 120 meters higher than Pakicetus by Thewissen in 1992
49 million years ago “the walking whale that
swims”- made possible by stout femur
More aquatic, similar to a sea lion
Anatomy of spinal column-swam with tail going up and down
Skull characteristics
Rodhocetus
49-43 million years ago in Pakistan by Stromer 1908
More developed tail for swimming
Sacral vertebrae not fused- more flexibility, first devotee to swimming
Femur was a third shorter than that of the Ambulocetus’
Skull elongated Ears pushed further back Smaller eyes First sea water living ancestors
Basilosaurus 35-41 million years ago by Cope in
1868 in Egypt and Eastern U.S. First completely aquatic form “king lizard”- 15 meters long Complete set of hind limb bones
and a pelvis, but very small First to have tail fluke- due to
structure of vertebral proportions Formation of blow hole-single large
nostril to the top of the head
Dorudon Found by Gingerich
1994, about 40 million years ago
Very similar to Basilosaurus, however smaller in size (4-5 meters long) and forelimbs and hind limbs smaller
Ability to walk on land completely diminished, move from land to sea is complete
Geographic Origins Use of the geographic
distribution of related species
Sea of Tethys Distribution of
Basilosaurus and Dorudon widely spread vs. Ambulocetus and Rodhocetus constrained to one area in India, Pakistan region
Genetic Changes Over Generations
Formation of the ear
Formation and movement of blow hole at top of the head
Vestigial Organs Pelvis, tibia, other
leg bone structures
Works Cited 1) Gingerich, Phillip. "The whales of Tethys." Apr. 1994. Aug 2013 < http://web.ebscohost.com/ehost/detail?vid=1&hid=3&sid=72aafebc-31f7-40ce-b541-44f44dbb72cb%40sessionmgr2&bdata=jmxvz2lucgfnzt1mb2dpbi5hc3amc2l0zt1lag9zdc1saxzl#db=aph&an=9404017813>. 2) Gingerich, Philip D., and D.E. Russel. "Pakicetus inachus, A New Archaeocete (Mammalia, Cetacea) from the Early-Middle Eocene Kuldana Formation of Kohat (Pakistan)." Paleontology, Museum of - Publications 25 (1981): 236-45. Aug 2013 3) Gingerich, Philip D. "Research on the Origin and Early Evolution of Whales (Cetacea)." Personal Pages. 5 Nov. 08. University of Michigan Aug 2013 <http://www-personal.umich.edu/~gingeric/pdgwhales/whales.htm>. 4) Myers, P. Z. "Evolution of Whale Ear." Pharyngula. 12 Aug. 2004. University of Minnesota, Morris. Aug 2013<http://pharyngula.org/index/weblog/comments/evolution_of_the_whale_ear/>. 5) "Researchers Discover Clues to Whale Evolution." Science Daily. 10 May 2002. Aug 2013<http://www.sciencedaily.com/releases/2002/05/020509073449.htm>. 6) Sutera, Raymond. "The Origin of Whales and the Power of Independent Evidence." Talk Origins. 10 Aug. 2001. Aug 2013 <http://www.talkorigins.org/features/whales/>. 7) Thewissen, J.G.M. "Whale Origins!" Northeastern Ohio Universities Colleges of Medicine and Pharmacy. Aug 2013<http://darla.neoucom.edu/depts/anat/whaleorigins.htm>. 8) "Whales Descended From Tiny Deer-like Ancestors." Science Daily. 21 Dec. 2007. Aug 2013<http://www.sciencedaily.com/releases/2007/12/071220220241.htm>.