3Characteristics of Mammals Hair – composed of keratin for insulation, sensation, appearance, and protection. (other keratinized structures – horns, antlers, etc.)Mammary Glands – modified sweat gland that, in females, produce milk to nourish their offspring.3 Middle Ear Bones – malleus, incus, and stapes (hammer, anvil, and stirrup); the first two derived from the ancestral jaw.
4Other mammal structures QuestionHair is made out of a protein calledlactose.keratin.mammalin.hemoglobin.Other mammal structuresmade of keratin:
5Characteristics of Mammals Highly differentiated teeth2 sets of teethSingle lower jaw bone4 chambered heartSecondary palateMuscular diaphragmHighly developed brainEndothermy and homeothermySeparate sexes (XX or XY)Internal fertilization
6Question Which of the following is NOT a characteristic of mammals? 4-chambered heartInternal fertilizationMuscular diaphragmMultiple lower jaw bonesAlthough mammals have only one lower jaw bone, they have three inner ear bones. The three mammalian ear bones were originally jaw bones, but have changed in size and function. The reduction in number of lower jaw bones is easily traced through fish, amphibian and reptile.
7Mammalian Teeth Heterodont teeth – different types of teeth 2 sets of teeth - DiphyodontDental Formula – shorthand way of describing teethDiastema – toothless gapCarnassial apparatusIncisors chisel shaped for gnawing and nipping (1 root)Canines long conical for catching, killing, and tearing (1 root)Premolars and Molars broad for chewing (1-2 or 2-3 roots)
8Question Mammals have “diphyodont” teeth. What does this mean? They have two sets of teeth.They have different types of teeth.They have a toothless gap in their teeth.They have more than two sets of teeth.All mammals are born with a temporaryset of teeth that are lost and replaced by apermanent set as they mature into adults.
9Mammalian GlandsGlands are an epidermal tissue that secrete substances.Sudoriferous – sweat for evaporative cooling and elimination of waste.Sebaceous – secrete oil for waterproofing of hair.Scent – secrete pheromones for defense, sex recognition, and territorial behavior.
10Cold Weather Adaptations Endothermy – the generation of internal heatHomeothermy – the maintenance of constant temperatureWinter Sleep – the organism is less active, alert, and easily aroused (Bears and raccoons)Hibernation – the organism slows metabolism, and heart and respiratory rates (monotremes, and some insectivora, rodentia, and chiroptera)
11Bears hibernate in the winter. QuestionTrue or FalseBears hibernate in the winter.Hibernation involves a slowing of heartbeat and respiration and usually a significant drop in body temperature. In contrast, bears enter a state of sedation referred to as “torpor.” Their metabolism slows down during the long winter sleep so that they do not need to eat, drink, urinate, or defecate until they emerge from their dens.
12Mammalian Classification Prototheria (Monotremes): oviparous (egg-laying).Metatheria (Marsupials): viviparous with a short gestation, further development occurring in a pouch.Eutheria (Placentals): viviparous with a long gestation.
13Question Which group of mammals is oviparous? Monotremes Marsupials PlacentalsAll of the above“Monotreme” is from the Greek “monos” meaning “single” & “trema” meaning “hole.” This refers to the fact that they possess a cloaca, through which a single egg is laid.
15Order Artiodactyla (Even-Toed Ungulates) Specialized for distance running with long hoofed legsNumber of teeth is variable but they all have a diastemaChambered stomachs for microorganisms to decompose cellulose into digestible componentsMales often sport antlers or hornsInclude deer, sheep, antelope, cows, hippopotamuses, camels, & giraffes
16Order Perissodactyla (Odd-Toed Ungulates) Simple stomachsMiddle toe is larger than the othersHorses, Rhinos, Tapirs
17Order CarnivoraAlthough not all current carnivora are carnivorous, the ancestors were meat eatersRecognizable carnassial apparatus for shearing meat and tendonsKeen senses and large brains3 upper and 3 lower incisorsDogs, cats, bears, raccoons, mustelids
18Order InsectivoraThird largest order of mammals and possibly the most primitive group of placental mammalsInsectivorousTaxonomy is currently being revisedMoles, shrews, and hedgehogs
19Order Lagomorpha Resemble large rodents with short tails Flaps of skin can close behind the incisors so that chewing can happen with the mouth closedFlaps of skin can also close the nostrils2 upper incisors, one behind the otherProduce two types of fecal material, one that is wet and eaten again for further nutrient absorption, and one that is dry and discardedRabbits
20Order Rodentia Largest mammalian order (40% of species) Individual upper and lower incisors that are rootless and grow throughout life for a gnawing life styleSquirrels, chipmunks, rats, mice, beavers, and porcupines
21Order Chiroptera Second largest mammalian order (20% of species) Bat wings are modified forelimbs with the flight surface covered with skin and supported by four fingersThe flight membrane usually extends down the sides of the body and attaches to the hind legsBats
22Order Primates Originally adapted as tree-dwellers Shortened nose and forwardly directed eyes, associated with stereoscopic visionMost live in the tropics or subtropicsLemurs, Tarsiers, Monkeys, Gibbons, and Apes
24Order Xenarthra Incisors and canines absent Xenarthra means "strange joints", and was chosen because their vertebral joints are unlike those of any other mammalsPlaced in a separate group from all other eutheriansAnteaters, sloths, and armadillos
25Order ProboscideaHave a long, muscular trunk that functions almost as a fifth limbHave a pair of huge tusks derived from upper incisorsTheir cheek teeth are uniquely adapted to their highly abrasive dietElephants
27QuestionWhich group of placental mammals has a name that literally means “strange joints?”PrimatesXenarthraProboscideaArtiodactylaTheir vertebral joints have extra articulations and are unlike those of any other mammals.