LIFE 103 1st Edition Lecture 27 Outline of Last Lecture I. Size of insectsII. VertebratesIII. Deuterostomia IV. EchinodermsV. Chordata VI. GnathostomesVII. OsteichthyesVIII. Lobe-fins IX. TetrapodsX. AmphibiansXI. AmniotesOutline of Current Lecture II. Mammalia III. Characteristicsa. Hair b. Milk c. Sound II. Mammal evolution III. Trends Current Lecture: Animal taxa: vertebrates (mammals and metabolic trade-offs) Mammalia I. Last group of amniotesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.II. Mammals evolved from reptiles III. 3 main groups of mammals: I. MonotremesAustralia/Asian (platypus)II. Marsupialskoalas! , mostly AustraliaIII. PlacentalsIV. Most diverse group are rodents, then batsI. Most mammals are brown and are nocturnal CharacteristicsI. Hair II. Young fed with milk produced by modified sweat glands (mammary glands)III. Sound conducted through middle ear by 3 bones (malleus, incus, stapes)IV. Each side of lower jaw made up of a single bone, the dentary HairI. No other animal group has itII. Found on all mammals at some point in developmentIII. KeratinIV. Molt patternsV. Complex patternsI. Arrector musclesII. Sebaceous glandsIII. Color variationVI. Viversee are earliest hair (whiskers are an example) MilkI. Young fed with milk produced by modified sweat glands (mammary glands)I. Also not found in any other group (pigeons, caecilians)II. Intense parental investment in offspringIII. Obligates female parent to invest heavily (lactation is often more expensive than gestation) Sound I. Sound conducted through middle ear by 3 bones (malleus, incus, stapes) (old bones are re-purposed…)II. Each side of lower jaw made up of a single bone, the dentary (feel it!)III. Remember: our perceptions about perception are influenced by our evolutionary history. Primates are very visual IV. Most mammals use olfaction and hearing more Mammal evolutionI. How did we get here? II. Pelycosaurs- evolution of homoiothermy (or homeothermy) I. Have sails that is a bony support that is highly vascularized III. Homeothermy- stable internal body temperature despite external influence, can be regulated behaviorally or metabolically IV. Poikilothermy- a body temperature that fluctuates with environmental conditions I. Switch between strategies TrendsI. Larger brainsII. Larger and more musclesIII. Upright limb postureIV. Nocturnal habitsI. These are all metabolically expensive V. How to address this problem? I. Heterodonty (specialized teeth): efficiency in processing food II. Secondary palate: i. Breathe while eatingii. Uninterrupted oxygen supply III. Endothermy! i. Blood vessels in fossilized bonesii. Evidence of whiskers (maybe fur) VI. Endothermy-generation and regulation of body temperature metabolically VII. Ectothermy- generation and regulation of body temperature from environmental sources Clicker question: which combination is most correct? All mammals are endothermic most are homeothermic, some are
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