1. The student is expected to: 7A analyze and evaluate how evidence of common ancestry among groups is provided by the fossil record, biogeography, and homologies, including anatomical, molecular, and developmental; 8B categorize organisms using a hierarchical classification system based on similarities and differences shared among groups; 8C compare characteristics of taxonomic groups, including archaea, bacteria, protists, fungi, plants, and animals

2. KEY CONCEPT All vertebrates share common characteristics.

3. The phylum Chordata contains all vertebrates and some invertebrates.
Chordates share four features at some stage of development.
notochord
hollow nerve cord
pharyngeal slits
tail
hollow nerve cord
tail
notochord
pharyngeal slits

4. Most chordates lose some or all of these characteristics in adulthood.
hollow nerve cord
tail
notochord
pharyngeal slits

5. All vertebrates share common features.
An endoskeleton allows vertebrates to grow to large sizes.
internal
made of bone or cartilage

6. An endoskeleton can be divided into four parts.
braincase (cranium)
braincase
vertebrae
bones
gill arches (in fish and some amphibians)
vertebrae
bones

7. There are seven classes of vertebrates.
Agnatha are jawless fish.
Cartilaginous and bony fish are characterized by the presence of jaws.
Amphibians are characterized by the presence of four limbs.
Reptiles, birds, and mammals are characterized by the presence of an amnion.
Birds are characterized by the presence of feathers.
Mammals are characterized by the presence of hair.

8. Agnatha
Chondrichthyes
Osteichthyes
Amphibia
Aves
Mammalia
JAWS
Jaws helped vertebrates to become successful predators.
VERTEBRAE
Vertebrates have a segmented backbone.
FOUR LIMBS
Four limbs let animals move from the water to life on land.
FEATHERS
Feathers insulate birds from the cold and allow for flight.
HAIR
Hair helps mammals to maintain constant body temperatures by roviding insulation from the cold.
lamprey
cartilaginous fish
bony fish
amphibians
birds
mammals

9. Fossil evidence sheds light on the origins of vertebrates.
Tunicates may be the closest relatives to vertebrates.
The first recognizable vertebrates were jawless fish.
Two groups of jawless fish still exist today.
lampreys
hagfish