Phylum Chordata - Chordates Internal skeleton with muscle ...

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Key Mammalian CharacteristicsHairHelps regulate body temperature, allows life in colder climatesNot derived from reptilian scales or feathersEach hair extends like stiff thread from bulb-like hair follicleComposed of dead cells filled with fibrous keratin proteinInsulates against heat lossProvides camouflageWhiskers function as sensory structuresServe as defensive weapons as in porcupines and hedgehogsMilk-producing glandsAll mammals have mammary glands that produce milkMammary glands are modified sweat glandsMilk is rich in fat, sugar, protein with 95% waterHigh calorie food needed to support rapid growth of newbornEvolution of MammalsArose from Therapsids in Triassic, 220 myaFirst mammals were small insectivoresHad large eyes - they may have been nocturnalMammal jaw reduced to massive bone with a single jointAllows strong biteTwo jaw bones moved to middle ear to make three bone chainthat improved hearing - malleus, incus, stapesWere a minor group until the Cretaceous (65 mya)Two groups - Prototheria and TheriaPrototheria - egg-laying mammalsclose relatives of therapsidsSmall, resembled modern shrewsTheria - live-bearing mammalsSubdivided into marsupials (pouched mammals) andplacental mammals
Characteristics of Modern MammalsEndothermyAllows activity in cooler weather and times of dayAllows colonization of harsh environments, deserts to arcticHair provides insulation to support endothermyHigher metabolic rate required as wellEfficient circulationprovided by four chambered heartImproved respirationDiaphragm breathing muscle allowsgreater volume of air to be inspiredPlacentaMost mammals are placental and viviparous (live bearing)Blood stream of mother and fetus in close contact at placentaFood, water, oxygen pass from mother to childWastes pass from child to mother, carried away
Page 4 and 5: The defining chordate characteristi
Page 6 and 7: The vertebrates are composed of eig
Page 9 and 10: Sharks became dominant predators ab
Page 11 and 12: Class Amphibia - Amphibiansincludes
Page 13 and 14: Modern AmphibiansOrder Anura - frog
Page 15 and 16: Dry skin with scales or armor reduc
Page 17 and 18: Dinosaurs - greater agilityLegs pos
Page 19 and 20: Other Important Characteristics of
Page 21 and 22: Class Aves - BirdsMost successful o
Page 23: Efficient circulationHas four-chamb
Page 27 and 28: Hooves, Horns, and Antlersclaws, fi
Page 29: Placental mammalsHave well-develope

Phylum Chordata - Chordates Internal skeleton with muscle ...

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