Mammalia

Mammal Evolution Mammals are believed to have evolved from Reptiles during the late Jurassic period

Mammal Evolution The first true mammal was a small, shrew-like organism that coexisted with Dinosaurs Ex. Hadrocodium fossil found in Northern China in 2002

Mammal Evolution Mammal’s inner-ear bones probably evolved from modified ancestral reptile jaw bones

3 Major Reproductive Categories Monotremes Egg-laying mammals (Ex. Echidna + Platypus)

3 Major Reproductive Categories Marsupials Embryos born very early and nurse from inside mother’s pouch (Ex. Kangaroo, Koala)

3 Major Reproductive Categories Placentals Embryos develop inside the womb, receiving nutrients and O2 from the mother via the Placenta Newborns fed milk from mammary glands.

Mammal Characteristics Characterized by hair and mammary glands Whales have very little hair

Mammal Characteristics Mammalian brains are more developed and specialized (cephalized) than any other class of animals

Mammal Characteristics All mammals have special sweat glands that are modified for producing milk, called Mammary glands

Mammal Characteristics Mammals are Heterodontic Teeth are differentiated Used for biting, grinding, tearing and crushing Ex. Incisors, molars, canines, etc.

Mammal Orders There are 19 orders of mammals We will look at the characteristics of 14 of them Order: Monotremata Lay Eggs (Ex. Echidna, Platypus) Order: Marsupiala Young grow in pouch (Ex. Koala)

Order: Insectivora Small pointed teeth, adapted mainly for eating insects Ex. Moles, Shrews, Hedgehogs

Order: Rodentia Nearly 50% of mammals are rodents Have no canine teeth, but two very larger incisors Almost all are herbivores Ex. Mice, Squirrels, Beavers

Order: Edentata Have no teeth Ex. Armadillos, Sloths, Anteaters

Order: Carnivora Very diverse group, Meat eaters Canine teeth highly developed Ex. Wolves, Bears, Raccoons, Otters, Skunks, Mongoose, Cats

Order: Serenia Aquatic mammals that breathe through their mouth and nose Herbivores Ex. Manatees and Dugongs

Order: Chiroptera Forelimbs adapted for flight May find prey by echolocation Ex. Insectivorous Bats, Old World Fruit Bats

Order: Lagomorpha Large incisor teeth Hindlimbs larger than forelimbs Ex. Rabbits and Pikas

Order: Cetacea Fully aquatic mammals Vestigial pelvic bones Evolved from a wolf/bear-like land mammal

Order: Cetacea Highly developed brain Have a dorsal blow-hole Ex. Toothed Whales, Baleen Whales

Order: Proboscidea Nose and top lip are highly enlarged into a muscular trunk for grasping items Ex. Elephants

Order: Primata Highly developed brains Often bipedal Ex. Lemurs, Monkeys, Apes, Humans

Order: Primata Humans are relatively new primates We appear to share a recent common ancestor with chimpanzees

Order: Artiodactyla Hooves with even-numbered toes Many of them are ruminants with a 4-chambered stomach Ex. Deer, Giraffe, Cattle, Pig, Camel, Hippo

Order: Perissodactyla Have odd-numbered toes Ex. Horses, Tapirs, Rhinoceroses