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monotremes. marsupials. egg layers. viviparous with pouch. 6 species. 250 species. Class Mammalia. placentals. placental viviparity. 3,800 species (17 orders). “ Age of mammals”- beginning of Tertiary period- 70 mya
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monotremes marsupials egg layers viviparous with pouch 6 species 250 species Class Mammalia placentals placental viviparity 3,800 species (17 orders)
“Age of mammals”- beginning of Tertiary period- 70 mya • First mammals small with delicate skeletons, acute senses and possibly nocturnal
Characteristics • Hair or fur called pelage • Keratinized derivative of epidermis • Periodically molted • Insulating layer • Important to sense of touch • Most have claws, nails or hooves
Glands • Sebaceous- oil • Sudoriferous- sweat • Scent or musk- pheromones • Mammary (functional in females)- milk • Monotremes- no nipples sebaceous sudoriferous mammary musk
Skull and teeth • Single articulation of jaw bone • 3 middle ear ossicles • More extensive secondary palate- can chew and breathe • Specialized teeth set into sockets of jaw • Most two sets- deciduous and permanent • Dental formula to identify • Types of teeth based on diet
Skeleton and muscles • Most have 7 cervical vertebrae • Trunk divided into thoracic and abdominal cavities by diaphragm • Skeleton bears body weight- muscles concentrated in upper appendages
Nutrition and digestion • Specialized to diet • Some have cecum- fermentation pouch (rodents) • Some ruminants- 4 stomach chambers (cows)
Circulation and gas exchange • 4 chambered heart • Placental mammals exchange nutrients from maternal to fetal blood • High metabolic rate • Efficient lungs
Warm blooded -heat production by shivering and brown fat -heat reduction through ears, tails, panting, burrowing or finding shade
Nervous system • Complex- enlarged cerebral cortex • Acute senses- touch, smell, auditory, vision (most not color)
Excretion • Metanephric kidneys excrete urea (more water loss)
Reproduction • Most have cycles (ova mature)- hormone regulated • Estrus (“heat”) • Some induced cycles (menstrual)
Behavior • Complex- often visual • Pheromones and marking • Grooming • Territoriality
hedgehogs moles Order Insectivora (third largest) shrews tenrecs
Order Chiroptera bats (second largest)
Order Rodentia (largest)
largest colonies largest rodent capybara prairie dogs can kill snakes can roll in ball mongoose pangolin
highest altitude "man of the forest" yak orangutan largest monkey largest herds mandrill springbok