1. Phylum: Chordata
Chapter 34

2. What you need to know! The 4 chordate characteristics.
Adaptations that allowed animals to move onto land.
Traits which distinguish each of the following groups: Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Birds, and Mammalia.
How the 3 classes of mammals differ in their reproduction.

3. Characteristics of all Chordates
Notochord: Longitudinal, flexible rod located between the digestive and the nerve cord
Nerve cord (dorsal, hollow): eventually develops into the brain and spinal cord (arthropods ventral)
Pharyngeal slits: become modified for gas exchange, jaw support, and/or hearing
Muscular, postanal tail

4. Neurulation (Vertebrates)
Neural Tube: dorsal folding of the ectoderm forming a hollow nerve tube
Neural Crest: embryonic cells (mesoderm) near the neural tube that migrate throughout the body to form special bones like the jaw and cranium
Animation:

5. Macroevolutionary Trends

6. Vertebrata
Pronounced Cephalization: concentration of sensory and neural equipment in the head
Cranium (skull): encloses brain
Endoskeleton: notochord becomes cartilage or bone (vertebral column) enclosing the hollow nerve chord
Bone is more advanced than cartilage
Hinged Jaw
Closed circulatory system with a ventral chambered heart

7. Land Adaptations Gills  lungs Paired lobed fins  legs (tetrapod)
Amniotic Egg (shelled egg): several extraembryonic membranes that are not part of the embryo, but produced by embryonic tissue:
Amnion: protects embryo, contains amniotic fluid for shock absorption
Allantois: forms extra sac for waste disposal and gas exchange
Yolk Sac: nutrient stockpile
Chorion: gas exchange

8. Amniotic Egg

9. Major Divisions
Fish
Class Chondrichthyes: flexible endoskeletons and jaws (i.e. shark and stingray)
Class Osteichthyes (bony fish): most numerous vertebrates, boney endoskeleton, scales (i.e. trout and salmon)
Class Amphibia: gas exchange across skin (most use lungs), soft water-based eggs, larvae have two-chambered hearts, adults have three chambers (i.e. frogs and salamanders)
Class Reptiles: gas exchange in lungs, intercourse, amniotic egg, scales (keratin), ectothermic, three chambered heart (i.e. turtles, lizards, and alligators)

10. Major Divisions
Birds (subdivision of reptiles): amniotic eggs, scales on legs, wings, feathers, endotherms, four chambered heart
Class Mammalia: milk from mammary glands, hair, endotherms, four chambered heart, large brains, teeth

11. Mammalian Subdivisions
Monotremes: egg laying mammals (i.e. platypuses and spiny anteaters)
Marsupials: born early, complete embryonic development in a pouch (i.e. kangaroos and opossums)
Placental mammals (eutherians): long pregnancy, fetus develops in the uterus (i.e. dogs and humans)