chapter 29- vertebrates

super class tetrapoda

4 limbs, includes all further groups

tetrapoda classes

amphibia, reptilia, aves, mammalia

class amphibia

first land vertebrates, limbs support weight outside water, most have lungs, cutaneous respiration, metamorphosis, skin + eggs lack protection, ectotherms

advantages of being on land

new food sources, escape from predators

cutaneous respiration

got O2 from skin, supplements the lungs

metamorphosis

hatch in aquatic environment with gills, develop lungs and become terrestrial

class amphibia orders

urodela, anura, apoda

order urodela

salamanders, many lack lungs (cutaneous or gills)

order anura

frogs + toads

order apoda

caecilians, porrly understood, limbless, burrowing

amniota

embryo surrounded by amniotic fluid, encased in amniotic sac

amniotic sac

cushions and hydrates embryo, eggs no longer need to be laid in water/moist place, can be in shell or mothers body

amniota clades

(based on temporal fenestra) anapsids, synapsids, diapsids

anapsids

no temporal fenestra, all extinct

synapsids

one temporal fenestra, mammals + proto-mammals

diapsids

two temporal fenstrae, reptiles + birds

class reptilia

paraphyletic, scaly skin, ectotherms

scaly skin

prevents water loss, can live in drier climates, downside=no cutaneous respiration

ectotherms

use environment to heat body, reduced caloric needs, sluggish in cold temps

class reptilia clade

dinosauria

clade dinosauria

diverse group, dominant vertebrates until extinction (except birds)

clade dinosauria orders

pterosauria, crocodilia, rhynochocephalia, squamata, testudines

order pterosauria

pterosaurs, fly, all extinct, not related to birds, not dinosaurs

order crocodilia

crocodiles, alligators, primarily aquatic carnivores

order rhynchocephalia

all extinct except tuatara, double row of upper teeth (part of jaw bone), poorly understood third eye

order squamata

snakes + lizards, largest order of reptiles

snakes are

part of members of tetrapoda clade that have lost their limbs as part of evolution

order testudines

turtles + tortoises, protective shell made of bone, anapsid morphology

testudines are not

apart of anapsid clade, temporal fenestra lost

class aves

birds, monophyletic, evolved from non-avian dinosaurs (flight was key), over 30 orders

traits of birds related to flight

endothermy, feathers, air-filled bones + beak, airflow in lungs

endothermy

higher body temp, helps muscles (high caloric needs)

bird feathers

asymmetrical, reduces heat loss (down)

air-filled beak + bones

reduces body weight

class mammalia

monophyletic, endothermy, hair, specialized teeth, mammary glands, placenta

mammals endothermy

like birds → convergent evolution

mammals hair

insulation, reduce heat loss, camouflage, sensory

mammals teeth

for many functions, most herbivores, helps offset high energy needs of endothermy

mammary glands

secrete high energy milk for newborns

placenta

facilitates fetal development

clade monotremes

lay shelled eggs (primitive placenta inside), duckbilled platypus

clade marsupials

live birth to underdeveloped young, due to primitive placenta, born very small and crawl into pouch in mother (nurse grow and develop)

clade placental mammals

more developed placenta, live birth of developed young

placental mammals orders

rodentia, lagomorphia, primates, perissodactylo, cetartiodactyla, carnivora,

order rodentia

rodents (mice, rats, squirrels)

order lagomorphia

rabbits + hares

order primates

monkeys + humans

order perissodactylo

horses + rhinos (odd-toed ungulates)

order cetartiodactyla

cows, pigs, hippos (even-toes ungulates)

order carnivora

cats, dogs, bears

order chrioptera

bats

order primates traits

grapsing finger and/or thumbs (opposable), stereoscopic vision (eyes on front, better depth perception)

key points in evolution of humans

bipedalium (walk on two feet), enlarged brain (enable to construct and use complex tools)