Chordates (Phylum Chordata) 1. Tunicates/Sea squirts 2. Lancelets II. Vertebrates Chordates (Phylum Chordata) 1. Tunicates/Sea squirts 2. Lancelets these 2 do not have vertebrae but have a type of nervous cord along back 3. Vertebrates (Subphylum Craniata)

Vertebrate Characteristics Bony vertebral column Nerve cord Cranium - surrounds anterior brain - bone or cartilage

1. Jawless Fishes (Superclass Agnatha) a. Hagfish b. Lampreys

2. Jawed Chordates (Superclass Gnathostoma) paired fins/lungs Jaws paired fins/lungs better fossil record (bones preserve better than soft tissue several classes Modern Fishes Jawless Ancestors

Classes of Gnathostoma Cartilaginous fishes (Class Chondrichtyes) Sharks and Rays

2. Bony Fishes (Class Osteichthyes)

Transition to Land

Tiktaalik roseae 375 mya fossil discovered in 2004 on Ellesmere Island in Cdn Arctic spent time on land and in water

3. Amphibians (Class Amphibia) - Salamanders, toads, frogs - Moist skin - Oviparous (lay eggs)

4. Reptiles (Class Reptilia) - Have amniotic egg - Can lay eggs in dry environments

5. Birds (Class Aves) beak feathers oviparous

6. Class Mammalia - Mammals

Mammal Characteristics 1. Skull

2. Hair - keratinized filaments

3. Mammary glands produce milk to nourish young derived from sweat glands

4. Teeth

5. Limb position ventral - positioned under body - differs from lateral position in ancestors

3 Groups of Mammals 1. Monotremes – oviparous (lay eggs)

2. Marsupials i. primitive placenta ii. altricial young (carried outside of body)

Placentals i. derived/advanced placenta ii. precocial young (carried inside) iii. most familiar mammals