Mar Mam notes test 1 - Marine Mammal Taxonomy Phylum...

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Marine Mammal Taxonomy Phylum Chordata Class Mammalia Order Cetacea o Suborder Odontoceti Family Physeteridae Family Kogiidae Family Ziphiidae Family Monodontidae Family Delphinidae Family Phocoenidae River dolphin families Toothed whales o Suborder Mysticeti Family Balaenidae Family Neobalaenidae Family Eschrichtiidae Family Balaenopteridae Baleen whales Order Sirenia o Family Trichechidae Manatees o Family Dugongidae Dugongs Order Carnivora
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o Family Phocidae "True seals" No external ear Rear flippers can't be used for walking o Family Otariidae Sea lions External ears Rear flippers can be used for walking o Family Odobenidae Walrus o Family Mustellidae Otters o Family Ursidae Polar bears   Marine Mammals Marine Mammal Evolution 65 Mya. End of Cretaceous (K-T Boundary) o Loss of most terrestrial and marine reptiles o Resulted in vacant niches= more food resources and fewer predators Someone must fill the gaps 54 Mya. Earliest  Cetacean  fossils o Didn't look like modern forms o Found first in Pakistan and Turkey, later in N. Africa and S.C. o Found along remnants of Tethys Sea Shallow, semi-circumglobal current 50 Mya.
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Earliest  Sirenians o Found in Egypt, Italy, and Jamaica o Also could be related to Tethys Sea and prevailing current 35-25 Mya. More  Orders / Families  of marine mammals o Driven by increase in coastal food resources o Antarctic circum-polar current sets up Dramatically changed climate and distribution of heat Ice caps form; Antarctica is isolated Resulted in more cold, sinking water= deep water circulation Upwelling in other areas caused an increase in production North Pacific rim and W. American coast became very productive More groups show up here first 33-10 Mya. Order Desmostylians o Found around N. Pacific rim o Only extinct order of marine mammals o 6 genera and 10 species 30-27 Mya. Pinnipeds o Found around N. Pacific rim 15 Mya. Bear-like carnivore o Found in Washington State 5 Mya. Aquatic sloth o Found in Peru
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1-3 Mya. Sea otters < 1Mya. Polar Bears Marine mammals evolved on land first and then moved into the water. o Why? New or increased food resources Fewer predators, avoid predation o Older group:  cetaceans  and  sirenians Have completely lost hind legs Cladistics An attempt to group animals into  clades Can also show evolutionary history and how closely related individuals are Methods for construction: o Physical characteristics (traditional) Go with the most  parsimonious  (simplest) arrangement Synapomorphies - shared characteristics o Genetics and molecular studies See how much of the genetic code is shared
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This note was uploaded on 04/13/2008 for the course MSCI 489 taught by Professor Young during the Spring '08 term at Coastal Carolina University.

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Mar Mam notes test 1 - Marine Mammal Taxonomy Phylum...

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