Class MammaliaMammals

CharacteristicsFur or hairSweat glandsMammary glands (females)

Most important mammalian characteristic

Diaphragm for breathingUse various combinations of fur, hair and

subcutaneous fat to conserve body heat

Three main categories1: Placentals

The young develop inside female uterus attached to a placenta = largest group

Three main categories2: Marsupials

Young are tiny an underdeveloped; they crawl to the female pouch, attach to a nipple an finish development there

Three main categories3: Monotremes

The young develop inside of eggs (similar to reptile eggs)

Most primitive group, 3 species left

Adaptations for movementLand

Well developed muscles and boneSkeleton is also highly flexibleLimb structure permits ease of motion

and speedCat family: has grasping claws for

climbing and holding preySnowshoe hair: elongated hind limbs for

hopping in the snowGrazing animals have modified toes to

help with speed

FlightOnly batsHave membrane between bones of

wings

WaterWhales, dolphins and porpoisesFront limbs have become flippersTail propels through waterStreamlined body allows for speed Blowhole instead of mouthOtters and seals have similar

adaptations but no blowhole

TeethIncisors: biting and tearingCanines: holding and piercingPremolars: chopping and grindingMolars: chopping and grindingHuman dental formula: 2123 (this means for every half of a jaw there are 2

incisors, 1 canine, 2 premolars and 3 molars)Dental plan varies depending on the feeding

habits

Digestive system:ruminants (cow, moose, deer,

camels)4 chambered stomachFirst two chambers for bacterial fermentationFood regurgitated for more mechanical

breakdown before entering last two chambersLast two chambers for chemical digestionThis is necessary because they live off of grass

which is hard to fully digest