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 probably arose from therapsids (200mya) which are mammal-like reptiles

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

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)

2. Marsupials Subclass – Theria or Metatheria Supercohort-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....

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....

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

Human classification/taxa Kingdom:   Animalia      Phylum:   Chordata           Subphylum:   Vertebrata                Class:   Mammalia                     Subclass:   Theria                          Infraclass:   Eutheria                               Order:   Primates                                    Suborder:  Anthropoidea                                         Superfamily:   Hominoide                                             Family:   Hominidae                                                   Genus:   Homo                                                        Species:   sapien 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