Vertebrates

characteristics

• notochord → vertebral column

• cranium (protects brain)

• endoskeleton

• diverse internal organs

gnathostomes

cartilaginous gill arches → hinged jaws

chondrichthyes

• buoyancy: oil filled liver & fins

• lateral line: senses movement in surrounding water

• reproduction:

  • oviparity: lay eggs

  • ovoviparity: egg retained in female

  • viviparity: eggs develop in uterus

osteichthyes

• bony skeleton

• operculum - covers gills

• swim bladder - buoyancy

origin of tetrapods

lobe finned → tetrapods → amphibians

amniotic egg

shelled egg that prevented deiccation on land

• reptiles, birds, mammals

• amniotes

• shell is permeable to O2 & CO2 but not H2O

monotremes

mammal lay eggs

marsupials

pouch mammals

eutherians

placental mammals