MammalsMammals

Bio II HonorsBio II Honors

RuppRupp

Origin and EvolutionOrigin and Evolution

4400 species4400 species More than 20 ordersMore than 20 orders Found on every continent and every Found on every continent and every

oceanocean

EndothermyEndothermy

Body heat Body heat produced through produced through metabolismmetabolism

Nearly constant Nearly constant temperaturetemperature

Regulated through Regulated through metabolism and metabolism and surface area surface area

HairHair

Main function is to Main function is to insulate against insulate against body heat lossbody heat loss

May also act as May also act as camouflagecamouflage

Completely divided heartCompletely divided heart

Four chambered Four chambered heart with two heart with two separate ventriclesseparate ventricles

Deoxygenated Deoxygenated blood does not mix blood does not mix with oxygenated with oxygenated bloodblood

MilkMilk

Females onlyFemales only Mammary glands Mammary glands

are modified sweat are modified sweat glands that glands that produce the milkproduce the milk

Single jawboneSingle jawbone

Unlike other Unlike other animals there is animals there is only one lower only one lower jawbonejawbone

Important in Important in identifying identifying mammal remains mammal remains due to decay of due to decay of other other characteristicscharacteristics

Specialized teethSpecialized teeth

Front teeth for Front teeth for biting and cuttingbiting and cutting

Side and back Side and back teeth for grindingteeth for grinding

Mammalian AncestorsMammalian Ancestors

300 million years ago 300 million years ago there were two major there were two major groups of animalsgroups of animals– One group gave rise to One group gave rise to

dinosaurs, birds, and all dinosaurs, birds, and all living reptilesliving reptiles

– The other group, the The other group, the synapsids, gave rise to synapsids, gave rise to mammals and their mammals and their relativesrelatives

Opening behind the Opening behind the eye in their skulleye in their skull

DimetrodonDimetrodon

TherapsidsTherapsids

The group that The group that rose from the rose from the synapsids and synapsids and gave rise to gave rise to mammals mammals

Many transitional Many transitional formsforms

Very complete Very complete fossil recordfossil record

Single jawbone Single jawbone witnessedwitnessed

Limbs moved Limbs moved under the bodyunder the body

Specialized teeth Specialized teeth evolvedevolved

Some may have Some may have been endothermic been endothermic and had hairand had hair

LycaenopsLycaenops

First MammalsFirst Mammals

Appeared the same Appeared the same time as the time as the dinosaurs—Triassic dinosaurs—Triassic periodperiod

Very small fossil Very small fossil remainsremains

Large eye sockets Large eye sockets suggests nocturnal suggests nocturnal existenceexistence

First MammalsFirst Mammals

By the end of the By the end of the Jurassic, 5 orders Jurassic, 5 orders of mammals had of mammals had evolvedevolved

Midway through Midway through the Cretaceous, 3 the Cretaceous, 3 main groups had main groups had evolvedevolved

Three Main Groups of MammalsThree Main Groups of Mammals

Monotremes—the egg layersMonotremes—the egg layers Marsupials—live birth, but short Marsupials—live birth, but short

internal development—pouched internal development—pouched animalsanimals

Placentals—live birth, long internal Placentals—live birth, long internal development, young nourished development, young nourished through a placentathrough a placenta

Diversification of MammalsDiversification of Mammals

Dinosaurs died out 65 myaDinosaurs died out 65 mya New habitats and niches opened up New habitats and niches opened up

and allowed evolutionary and allowed evolutionary diversificationdiversification

Benefits of EndothermyBenefits of Endothermy Able to live in cold Able to live in cold

climatesclimates Energy is available to Energy is available to

perform tasks for long perform tasks for long periods of timeperiods of time

Organ systems are Organ systems are arranged differentlyarranged differently

Food intake is Food intake is increasedincreased

Insulation to heat loss Insulation to heat loss through hair and fat through hair and fat layerslayers

Respiratory SystemRespiratory System

Very efficient Very efficient systemsystem

Large lungs and Large lungs and many alveoli for many alveoli for gas exchangegas exchange

Diaphragm to aid Diaphragm to aid inhalationinhalation

Tooth TypesTooth Types Incisors to cutIncisors to cut Canines to grip and punctureCanines to grip and puncture Premolars to shred and grindPremolars to shred and grind Molars to grind and crushMolars to grind and crush Baleen in whalesBaleen in whales

Plant DigestionPlant Digestion

CelluloseCellulose Multi-chambered Multi-chambered

stomachstomach Rumen—contains Rumen—contains

microorganismsmicroorganisms Regurgitate and chew Regurgitate and chew

the partially digested the partially digested cudcud

Cecum—fermentation Cecum—fermentation chamberchamber

Nervous Systems and Sense Nervous Systems and Sense OrgansOrgans

Enlargement of cerebrum accounts Enlargement of cerebrum accounts for the large brains of mammalsfor the large brains of mammals– Evaluates inputEvaluates input– Controls movementControls movement– Initiates and regulates behaviorInitiates and regulates behavior

Five sensesFive senses Various heightened senses depend Various heightened senses depend

on environment, Ex. Bats and on environment, Ex. Bats and echolocationecholocation

Monotreme ReproductionMonotreme Reproduction

Lays one to two Lays one to two leathery eggs and leathery eggs and incubates themincubates them

Developing embryo Developing embryo is nourished by the is nourished by the yolkyolk

Marsupial ReproductionMarsupial Reproduction

Very short internal Very short internal developmentdevelopment

At the point when At the point when they can survive they can survive outside the outside the mother’s body they mother’s body they emerge and move emerge and move into the pouchinto the pouch

Placental Mammal ReproductionPlacental Mammal Reproduction

Most familiar type Most familiar type of mammal of mammal reproductionreproduction

Long developmentLong development Nourished through Nourished through

a placenta a placenta containing blood containing blood vessels of mother vessels of mother and offspringand offspring

Order MonotremataOrder Monotremata Egg-layersEgg-layers Three speciesThree species

– PlatypusPlatypus– Two types of anteater or echidnaTwo types of anteater or echidna

PlatypusPlatypus– Aquatic adaptations—webbed feet, flattened tail, Aquatic adaptations—webbed feet, flattened tail,

duckbill muzzleduckbill muzzle– Nippleless mammary glandsNippleless mammary glands

EchidnaEchidna– TerrestrialTerrestrial– Coat of protective spinesCoat of protective spines– Probing noseProbing nose

Order MarsupialiaOrder Marsupialia

About 280 speciesAbout 280 species Only one U.S. species—OpossumOnly one U.S. species—Opossum Inhabit Australia, New Guinea, Inhabit Australia, New Guinea,

AmericasAmericas As Pangea drifted apart the isolation As Pangea drifted apart the isolation

allowed for diversification and allowed for diversification and domination in certain regions of domination in certain regions of these organisms—many were these organisms—many were replaced by placental mammalsreplaced by placental mammals

Placental MammalsPlacental Mammals Order Order RodentiaRodentia Order Order EdentataEdentata Order Order LagomorphaLagomorpha Order Order InsectivoraInsectivora Order Order PrimatesPrimates Order Order ChiropteraChiroptera

Order Order CarnivoraCarnivora Order Order ArtiodactylaArtiodactyla Order Order PerissodactylaPerissodactyla Order Order CetaceaCetacea Order Order SireniaSirenia Order Order ProboscideaProboscidea

Order Order RodentiaRodentia

Largest order with about 1800 species, about Largest order with about 1800 species, about 40% of all placental mammals40% of all placental mammals

Not found on AntarcticaNot found on Antarctica Two pairs of incisorsTwo pairs of incisors High reproductive capacityHigh reproductive capacity

Order Order EdentataEdentata

About 30 living About 30 living speciesspecies

Anteaters, sloths, Anteaters, sloths, armadillosarmadillos

EdentataEdentata means means “toothless”, “toothless”, anteaters have no anteaters have no teeth, armadillos teeth, armadillos and sloths have and sloths have peg-like teeth with peg-like teeth with no enamelno enamel

Order Order LagomorphaLagomorpha

Roughly 70 species Roughly 70 species including rabbits, including rabbits, hares, and pikashares, and pikas

Double row of Double row of upper incisorsupper incisors

Order Order InsectivoraInsectivora

About 390 speciesAbout 390 species Shrews, hedgehogs, Shrews, hedgehogs,

molesmoles High metabolic rateHigh metabolic rate Found in North Found in North

America, Europe, Asia, America, Europe, Asia, and Africaand Africa

Pointed, probing nosesPointed, probing noses Arboreal, Arboreal,

subterranean, or subterranean, or terrestrial adaptationsterrestrial adaptations

Order Order PrimatesPrimates

235 species235 species Prosimians—lemurs, tarsiers, lorisesProsimians—lemurs, tarsiers, lorises Anthropoids—monkeys, apes, humansAnthropoids—monkeys, apes, humans OmnivorousOmnivorous Large brainsLarge brains Variation in size-from 10 grams to 400 lbs.Variation in size-from 10 grams to 400 lbs. Forward facing eyes, and grasping handsForward facing eyes, and grasping hands

ProsimiansProsimians

AnthropoidsAnthropoids

Order Order ChiropteraChiroptera

More than 900 More than 900 speciesspecies

BatsBats Wing is a modified Wing is a modified

hand with a hand with a membrane membrane stretched over itstretched over it

Order Order CarnivoraCarnivora 274 species274 species Dogs, cats, bears, Dogs, cats, bears,

raccoons, seals, raccoons, seals, hyenas, etc.hyenas, etc.

Meat eaters that Meat eaters that typically have long typically have long canines, strong jaws, canines, strong jaws, and clawed toesand clawed toes

Long limbs to aid in Long limbs to aid in runningrunning

Pinnipeds—aquatic Pinnipeds—aquatic such as seals, such as seals, walruseswalruses

Order Order ArtiodactylaArtiodactyla About 210 speciesAbout 210 species Also known as the Also known as the

ungulates or hoofed ungulates or hoofed mammals—have even mammals—have even number of toesnumber of toes

Deer, elk, sheep, goats, Deer, elk, sheep, goats, pigs, camelspigs, camels

Native to every continent Native to every continent except Australia and except Australia and AntarcticaAntarctica

Use speed as defense Use speed as defense Typically herbivoresTypically herbivores RumenRumen

Order Order PerissodactylaPerissodactyla 17 living species17 living species Ungulates with odd Ungulates with odd

number of toesnumber of toes Horses, zebras, Horses, zebras,

rhinoceroses, tapirsrhinoceroses, tapirs Most are native to Most are native to

Africa and AsiaAfrica and Asia Tapirs can be found in Tapirs can be found in

Central and South Central and South AmericaAmerica

Cecum instead of Cecum instead of rumenrumen

Order Order CetaceaCetacea

90 species of whales, dolphins, and porpoises90 species of whales, dolphins, and porpoises Forelimbs are flippers, hind limbs modified to flippersForelimbs are flippers, hind limbs modified to flippers Blowholes and blubberBlowholes and blubber Echolocation for navigationEcholocation for navigation Entirely aquatic, but evolved from land mammalsEntirely aquatic, but evolved from land mammals Toothed whales and baleen whalesToothed whales and baleen whales

Toothed versus BaleenToothed versus Baleen

Order Order SireniaSirenia

4 species4 species Manatees and Manatees and

dugongsdugongs Inhabit rivers, Inhabit rivers,

estuaries, and tropical estuaries, and tropical waterswaters

Flippers and no hind Flippers and no hind limbs like cetaceanslimbs like cetaceans

Closely related to Closely related to elephantselephants

Order Order ProboscideaProboscidea

3 species3 species Boneless, trunked Boneless, trunked

nose, or proboscisnose, or proboscis ElephantsElephants Modified incisors Modified incisors

called tuskscalled tusks Long gestationLong gestation Live to about 80Live to about 80