35.1    The Natural History of Mammals

	Mammary glands secrete milk that nourishes mammalian young.
	Smallest mammal is shrew.
	Largest mammal is the blue whale.
	Mammals foraged for food at night to avoid predatory dinosaurs during the day.
	Enothermic mammals require 10 times more food than ectothermic reptiles of the same size in order to generate and maintain a warm body temperature.
	The decline of dinosaurs may have been due to them not being able to eat newly evolved plants, angiosperms.

35.2    Mammalian Diversity

	Monotremes are mammals that lay eggs and have a cloaca into which urinary, digestive and reproductive tracts open.
	There are 3 species of monotremes with the best known as the duck-billed platypus.
	The other is the echidna ( spiny anteaters ).
	Before placental mammals evolved, Australia broke away from other land masses.
	Almost 95% of all mammals are placentals.
	Elephants were on the brink of extinction because of the hunting practice for their ivory.

35.3    Structure and Function in Mammals

	Most mammals have various types of teeth and can eat a wider range of foods.
	Some artiodactyles have an extra chamber in their stomach called a rumen.
	When the diaphragm contracts, the chest cavity enlarges, causing air to rush into the lungs.
	Desert-dwelling mammals conserve water by forming small volumes of concentrated urine.
	Cerebellum coordinates movement and balance, which makes running, walking, swimming or flying possible.
	Mammalian brain evolved faster than the skull bones housing it.
	Dogs, bats and other mammals can detect higher frequency sound waves than humans.
	It is their practice of living in such dense populations that makes bats so vulnerable.

35.4    Mammalian Reproduction

	Monotremes lay eggs similar to reptilian eggs.
	Marsupial reproduction has advantages over monotreme reproduction.
	Marsupial can move around to look for food or escape from predators while their young is nursing.
	Gestation period increases size of adult and degree to which newborns are developed.
	Newborn marsupials mammals are more fully developed and independent than newborn marsupials.

Back to course outline