Vertebrates Jawless fishes to Mammals Gills to Lungs Fish – one way circulation Amphibians – circulation loop Reptiles – partial septum - little mixing of blood Mammals 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 scales Protective operculum over the gills Swim bladder for buoyancy Ray finned fish – most bony fish like the tuna, bass, perch Lobed finned fish – ancestor to the amphibians

Osteicthyes

Perch anatomy

Lobed finned fish

Fish circulation

Amphibians Living a double life – part water/part land Gas exchange through diffusion Complete metamorphosis Partially divided heart Ex. 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 Aves Evolved during the mesozoic era Honeycombed bones for lighter weight Wings for flight, feathers made of keratin Endothermic – warmed by own metabolism No teeth, grind food with gizzard

Birds

Mammals Became diverse after the downfall of the dinosaurs Hair and mammary glands Endotermic Monotremes – duck-billed platypus and echidna, egg-laying mammals Marsupials – pouched mammals Eutherians – placental mammals

Mammal Heart

Echidna

Marsupials and Eutherian

Evolution of Primates Evolved in late Cretaceous period Arboreal – tree dwelling Limber shoulder joints allows to brachiate – swing from limb to limb Prosimians – lemurs, tarsiers Anthropoids – Monkeys, humans, apes