10. What are the six criteria
used to build a complete
evolutionary branch of
vertebrates?

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
Dichotomy in each the six following
builds the vertebrate
branch: absence of
separates cyclostomes from
; absence of limbs
fishes from the ; absence of
osseous separates
chondrichthian (cartilaginous)
from osteichthyes; absence
impermeable skin separates
from the terrestrial ;
absence of warm (homeothermic
body) separates from birds and
; absence of mammary
and hair separates from
mammals.