Mammals

Key Features Hair – keratin Mammary glands Parental care of young

Mammalian Taxonomy

Monotremes Egg laying mammals –Leathery outer covering Found in Australia and New Zealand Produce milk

Duck-billed Platypus

Egg laying Feed young milk Platypus With Young

Echidna - Monotreme

Marsupial Live born young –Very immature –Develop in pouch Cretaceous Today

Continental Drift

Koala – Marsupial

Marsupial Young Short gestation Long lactation

Placental Mammals Eutherians Diverged from Marsupials ~90 mya

Placental Mammals 10 major orders –Artiodactyla – even toed hoofs, deer, cows –Carnivora – carnivores, cats, dogs –Cetacea – whales and dolphins –Chiroptera – bats –Insectivora - shrews –Lagomorpha – rabbits –Perissodactyla – odd toed hoofs, horses –Primates – humans, monkeys, apes –Rodentia – rats, squirrels –Pinnipedia – seals and sea lions

Fetus is nourished through placenta Long gestation period

Gestation vs. Lactation

Placenta formation –inner cell mass (embryo) –trophoblast (embryonic portion of placenta) Placental Mammals

Tooth Structure Side to side movement of jaw Grinding of plant material Up and down movement of jaw Scissor-like cutting of flesh

Tooth Function

Jaw Structure Deer Coyote

Jaw Structure Herbivore –Lack canines –Selenodont teeth –Side to side movement –Diastema Carnivore –Large canines –Secodont teeth –Wide gape –Teeth interlock –Carnasial teeth to cut flesh

Gastrointestinal Tracts

Stomach Comparison

Ruminant Stomach

Rumination Rumen –Microorganisms digest cellulose –Some nutrients absorbed through wall of rumen –Rumination (chewing cud) Reticulum and Omasum –Absorb water –Slowly pass material from rumen to abomasum Abomasum –True stomach –Digestion of microorganisms –Digestion of proteins

Hoofed Carnivores Pakicetus Whales With Legs Modern Whales Hoofed Herbivore Modern Hoofed Herbivore Gingerich’s 1984 Theory of Whale Evolution

Pakicetus Is Pakicetus an ancestor of the Whale?

Genetic Evidence Decode the DNA – DNA sequencing Compare with DNA code of other organisms Determine which organism have the best fit

Artiodactyls

Gingerich’s 2001 Discovery Whales with Artiodactyl-like ankle bones

Hoofed Mammals Single Pulley Hoofed Carnivores Pakicetus Single Pulley Deer, Antelope, Hippos etc. Double Pulley Whales With Legs Double Pulley Modern Whales No Legs 65 my 55 my 5 my Hoofed Mammal Double Pulley

Vertebrate Swimming Fish –Tail vertically compressed –Movement side-to-side Whale –Tail horizontally compressed –Movement up-and-down

Whale Spine Movement Movement of whale spine swimming similar to movement of land mammal running