superclass gnathostomata

Question 1

what characteristics does this superclass contain?

Answer 1

jawed mouth and enlarged forebrain

Question 2

how does an enlarged forebrain help these organisms?

Answer 2

enhances smell/vision, better predatory behavior, helps detect changes in current vibrations, and low freq sounds

Question 3

how did jaws most likely evolve?

Answer 3

through modification of the anterior most pair of pharyngeal slits

Question 4

when did the first gnathostome fossils appear?

Answer 4

440 mya

Question 5

what are some reasons for success of gnathostomes?

Answer 5

paired fins, jaws, and tails

Question 6

what are placoderms?

Answer 6

an extinct lineage of armored vertebrates

Question 7

what class is included in this superclass and what organisms does it contain?

Answer 7

class chondrichthyes: sharks, rays, skates, ratfishes

Question 8

what are these animals composed of?

Answer 8

cartilaginous skeletons

Question 9

describe the swimming characteristics of these organisms? (3)

Answer 9

1) swift swimmers due to streamlined body
2) gain buoyancy by storing oil in the liver
3) continual swimming ensures water flow for respiration