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7. Class - Mammalia ~4500 species in 19 orders

7. Class - Mammalia ~4500 species in 19 orders. Characteristics hairy animals with glands that produce milk maintain constant body temp. most develop in the uterus where they are nourished by a placenta limbs are under the body, directed downwards fully mobile jaw and socket teeth. Origins.

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7. Class - Mammalia ~4500 species in 19 orders

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  1. 7. Class - Mammalia~4500 species in 19 orders Characteristics • hairy animals with glands that produce milk • maintain constant body temp. • most develop in the uterus where they are nourished by a placenta • limbs are under the body, directed downwards • fully mobile jaw and socket teeth

  2. Origins • probably arose from therapsids (200mya) which are mammal-like reptiles

  3. survival was probably enhanced by carrying embryos within the body, bearing live young, and the constant food supply (milk) • by the end of the Mesozoic era (65 mya) mammals diverged from the original line to three “groups” (probably sub-classes) -- Monotremes, Marsupials, and Placentals

  4. 1. Monotremes Subclass: Protothereia, Order: Monotremata • egg (leathery)-laying mammals • have a sense of electroreception to locate their prey • only five species exist, the duck-billed platypus and four sp. of spiny anteaters (Echidna) • single hole that serves the urinary tract, anus, and reproductive tract Ornithorhynchidae (Ornithorhynchus anatinus)

  5. 2. Marsupials Subclass – Theria or MetatheriaSupercohort-Marsupialia • the pouched animals- 272 species. • short gestation time is due to having a yolk-type placenta in the mother marsupial • young are typically born in a practically embryonic state (2cm). • Ex. Opossum, koala, wallaby, wombat, kangaroo, and Tasmanian Devil....

  6. 3. Placentals(subclass Eutheria) • nourished in the uterus through a specialized embryonic organ attached to the uterus wall called the placenta allowing longer gestation times. • 4000+ species. whales, bats, elephants, armadillos, dogs, sheep, cattle, and humans....

  7. Order – Primates Characteristics and origins • 233 living species placed in 13 families • most have long arms, prehensile (grasping) tail and hands with fingernails • stereoscopic vision with eyes in front of head • brain adapted for learning • probably arose about 65 mya • early primates were more like rodents that lived in trees

  8. Kingdom: Animalia Phylum:Chordata Subphylum:   Vertebrata Class:   Mammalia Subclass:   TheriaInfraclass:   EutheriaOrder:   Primates Suborder:  AnthropoideaSuperfamily:   Hominoide Family: HominidaeGenus:  HomoSpecies: sapien Human classification/taxa • Animalia • Chordata • Mammalia • Primate • Hominidae • Homo • sapiens sapiens Did Humans Evolve video clip http://www.pbs.org/wgbh/evolution/library/11/2/e_s_5.html

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