Evolution of Tetrapods The move onto land 365 mya

Lobe-fin Fishes Ancestor Lead to 3 groups of lobe-finned fish 1) Lungfish 2) Latimeria ( a deep ocean fish once thought extinct) 3) tetrapod ancestor

Icthyostega : Tetrapod common ancestor 2 Extant Branches Amphibians Amniotes

Class Amphibia Reproduce in water Eggs with no shell Larvae fish-like gills 2 chamber heart Adults tetrapod-like lungs 3 chamber heart

3 Orders of Amphibians 1) Salamanders & newts 2) Frogs & Toads 3) Cecilians

Amniotes Embryos protected by membrane called amnion. The amnion holds liquid around the embryo Amnionic fluid Reptiles were the first Amniotes. Amniote eggs let reptiles move farther from water.

Evolutionary Advantage of the Move to land Few predators lots of food and space

Adaptations needed for land: 1) Lungs a) amphibians also get O2 through skin b) had to lose scales c) only damp skin can take up O2

2) Legs A) bonds connect to spine B) lift body C) same bones In all vertebrates

3) Improved circulatory system Larval amphibians & fish (1 loop) Adult amphibians & tetrapods. (2 loops)

Adaptations to move to inland (far from water) Amnion to keep embryo from drying out Waterproof skin to keep YOU from drying out Reptiles developed scales for waterproofing Waterproof is air proof too so needed better lungs (more folding = more surface area)

Class Reptilia 1) scales 2) improved lung 3) 3 chambered heart (some 4) 4) amniote eggs

Orders of Extant Reptile 1) turtles & tortoises 2) snakes and lizards 3) tuatara 4) crocodilians

Some reptiles became dionsaurs then Some dinosaurs became birds

Class Aves (birds) Amniote egg Feathers (modified scales) Wings & flight Warm blooded 4 chamber heart Most advanced lung

Class Mammalia Hair Mammary glands (milk) Amnion Warm blooded 4 chamber heart 2nd best lung w/ alveoli Came from a primitive reptile ancestor