Vertebrates

Jawless fishes to MammalsGills to LungsFish – one way circulationAmphibians – circulation loopReptiles – partial septum - little mixing of

bloodMammals and Birds – completely divided

Fish

Classes• Agnatha – Jawless fish, evolved about 540

MYA. Ex. Lamprey• Chondrichthyes – cartilaginous fishes. Ex.

Sharks and rays• Osteichthyes – bony fish• Gills for respiration

Agantha - Lamprey

Jaw evolution

Sharks

Fast, powerful predators, Lateral line system – sensory organs

running down the side of the body for detecting vibrations in the water

Chondricthyes

Bony Fish

Hard skeleton with scalesProtective operculum over the gillsSwim bladder for buoyancyRay finned fish – most bony fish like the

tuna, bass, perchLobed finned fish – ancestor to the

amphibians

Osteicthyes

Perch anatomy

Lobed finned fish

Fish circulation

Amphibians

Living a double life – part water/part landGas exchange through diffusionComplete metamorphosisPartially divided heartEx. Salamander, frogs

Amphibians

Amphibian circulation

Reptiles

Watertight skin and eggs Internal fertilization – no water needed Ectothermic Scales made of keratin Lungs Dinosaurs were numerous during the Mesozoic

era By about 65 MYA, the dinosaurs were gone,

with only the birds left. Turtles, crocodiles, lizards and snakes

Reptile Heart

Reptiles

Archaeopteryx

Birds

Class AvesEvolved during the mesozoic eraHoneycombed bones for lighter weightWings for flight, feathers made of keratinEndothermic – warmed by own

metabolismNo teeth, grind food with gizzard

Birds

Mammals

Became diverse after the downfall of the dinosaurs

Hair and mammary glandsEndotermicMonotremes – duck-billed platypus and

echidna, egg-laying mammalsMarsupials – pouched mammalsEutherians – placental mammals

Mammal Heart

Echidna

Marsupials and Eutherian

Evolution of Primates

Evolved in late Cretaceous periodArboreal – tree dwellingLimber shoulder joints allows to brachiate

– swing from limb to limbProsimians – lemurs, tarsiersAnthropoids – Monkeys, humans, apes