KINGDOM ANIMALIAPhylum Chordata

Subphylum VertebrataClass Mammalia

Vertebrate Classes

Characteristics of MammalsHair – 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.

Question

Hair is made out of a protein calledA. lactose.B. keratin.C. mammalin.D. hemoglobin.

Other mammal structures made of keratin:

Characteristics 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

QuestionWhich of the following is NOT a characteristic of mammals?

A. 4-chambered heartB. Internal fertilizationC. Muscular diaphragmD. Multiple lower jaw bones

Although 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. 

Mammalian TeethHeterodont teeth – different types of teeth2 sets of teeth - DiphyodontDental Formula – shorthand way of describing teethDiastema – toothless gapCarnassial apparatus1. Incisors chisel shaped for

gnawing and nipping (1 root)2. Canines long conical for

catching, killing, and tearing (1 root)

3. Premolars and Molars broad for chewing (1-2 or 2-3 roots)

QuestionMammals have “diphyodont” teeth. What does this mean?

A. They have two sets of teeth.B. They have different types of teeth.C. They have a toothless gap in their

teeth.D. They have more than two sets of

teeth.All mammals are born with a temporary

set of teeth that are lost and replaced by apermanent set as they mature into adults.

Mammalian GlandsGlands are an epidermal tissue that secrete substances.1. Sudoriferous – sweat for

evaporative cooling and elimination of waste.

2. Sebaceous – secrete oil for waterproofing of hair.

3. Scent – secrete pheromones for defense, sex recognition, and territorial behavior.

Cold Weather Adaptations

Endothermy – the generation of internal heat

Homeothermy – the maintenance of constant temperature

Winter 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)

Question

True or False

Bears 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.

Mammalian Classification

1. Prototheria (Monotremes): oviparous (egg-laying).

2. Metatheria (Marsupials): viviparous with a short gestation, further development occurring in a pouch.

3. Eutheria (Placentals): viviparous with a long gestation.

Question

Which group of mammals is oviparous?

A. MonotremesB. MarsupialsC. PlacentalsD. All 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.

Terrestrial Placental Orders

1. Order Artiodactyla2. Order Perissodactyla3. Order Carnivora4. Order Insectivora5. Order Lagomorpha6. Order Rodentia7. Order Chiroptera8. Order Primates9. Order Xenartha10.Order Proboscidea

Order Artiodactyla(Even-Toed Ungulates)

Specialized for distance running with long hoofed legs

Number of teeth is variable but they all have a diastema

Chambered stomachs for microorganisms to decompose cellulose into digestible components

Males often sport antlers or horns

Include deer, sheep, antelope, cows, hippopotamuses, camels, & giraffes

Order Perissodactyla(Odd-Toed Ungulates)

Simple stomachsMiddle toe is larger

than the othersHorses, Rhinos, Tapirs

Order Carnivora

Although not all current

carnivora are carnivorous, the ancestors were meat eaters

Recognizable carnassial apparatus for shearing meat and tendons

Keen senses and large brains

3 upper and 3 lower incisors

Dogs, cats, bears, raccoons, mustelids

Order Insectivora

Third largest order of mammals and possibly the most primitive group of placental mammals

InsectivorousTaxonomy is currently

being revisedMoles, shrews, and

hedgehogs

Order Lagomorpha

Resemble large rodents with short tailsFlaps of skin can close behind the

incisors so that chewing can happen with the mouth closed

Flaps 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 discarded

Rabbits

Order RodentiaLargest mammalian

order (40% of species)Individual upper and

lower incisors that are rootless and grow throughout life for a gnawing life style

Squirrels, chipmunks, rats, mice, beavers, and porcupines

Order Chiroptera

Second largest mammalian order (20% of species)

Bat wings are modified forelimbs with the flight surface covered with skin and supported by four fingers

The flight membrane usually extends down the sides of the body and attaches to the hind legs

Bats

Order PrimatesOriginally adapted as tree-

dwellersShortened nose and

forwardly directed eyes, associated with stereoscopic vision

Most live in the tropics or subtropics

Lemurs, Tarsiers, Monkeys, Gibbons, and Apes

Order Primates

Order Xenarthra

Incisors and canines absent

Xenarthra means "strange joints", and was chosen because their vertebral joints are unlike those of any other mammals

Placed in a separate group from all other eutherians

Anteaters, sloths, and armadillos

Order ProboscideaHave a long, muscular trunk that

functions almost as a fifth limbHave a pair of huge tusks derived from

upper incisors Their cheek teeth are uniquely adapted to

their highly abrasive dietElephants

Order Proboscidea

QuestionWhich group of placental mammals has a name that literally means “strange joints?”

A. PrimatesB. XenarthraC. ProboscideaD. Artiodactyla

Their vertebral joints have extra articulations and are unlike those of any

other mammals.

Aquatic Placental Orders

1. Order Carnivora – Otters, Weasels, Seals, Walruses, Sea Lions

2. Order Cetacea – Whales, Dolphins, Porpoises

3. Order Sirenia – Manatees, Sea Cows