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flexible, sturdy rod along length of animal, between nerve cord and gut

Nerve cord

nervous tissue (a.k.a. spinal cord)

Pharyngeal slits

the pharynx portion of the gut opens to the outside

Muscular tail

the body extends beyond the anus


subphylum, do not have a true backbone, but they have the characteristics of other chordates (ex. tunicates, sea squirts)


do have a true backbone (vertebrae), spinal cord is enlarged at one end (brain)


oldest vertebrate fossils, lacked a jaw


jawless vertebrates, could not chew food, used pharyngeal slits, gills, 500 mil years ago (ex. lamprey)

fish jaw

major evolutionary step for fish, gills became hardened with cartilage, could eat big pieces of food

cartilaginous fish

fish that used cartilage as the hard substance for skeleton

fish bones

second big step for fish, cartilage became hardened due to presence of calcium salts (calcium phosphate)

vertebrae, jaws, lungs, limbs

what fish gave us


first vertebrates to move on land (evolved from lungfish), increased use of limbs, dependence on oxygen


first tetrapods, mostly carnivorous, cold-blooded (ectoderms), longer snout, mobile neck, highly flexible

buccal pumping

no operculum, large gular plates, breathes air (ex. frogs do this when their throats get big and small)

frog development

eggs laid in water, then tadpoles develop and breathe with gills, skin of adults must be moist at all times (limited habitats)


reptiles, birds, and mammals, amniotic sac allows them to be fully terrestrial


amnion membrane (protection), chorion membrane (gas exchange), allantois sac (waste disposal), yolk sac (nutrients)


evolved from amphibians, live in drier habitats, skin covered in keratin protein for protection, ectothermic but they regulate temp


large terrestrial reptiles from 300-65 mil years ago, diverse lifestyles, very agile/fast, mass extinction at end of cretaceous period


evolved from dinosaurs, scales on legs only, honeycomb bones, very good eyesight, endothermic

social characteristics of birds

controlled flight, complex courtship rituals, social bonding/ extended parenting, amazing navigation skills using sun/moon/stars


genus of extinct sarcopterygian (lobe-finned "fish")


exhibits transitional features between lobe-finned fishes and early tetrapods


jawed fish, paired fins (ex. sharks, sting rays)


subphylum of chordata, presence of a notochord (ex. lancelets)

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