Lecture 5+6

Question 1

What are key things to note about the lamprey skeleton?

Answer 1

1) The skeleton is situated mostly in the head and along the trunk region
2) There is a branchial basket
3) Skeleton consists of slender cartilaginous elements
4) There are slender rays in the caudal fin
5) Slightly elaborate braincase

Question 2

What are anaspids?

Answer 2

An early branch of the cyclostome stem

• no paired find
• single and anal fin
• hypocercal tail

Question 3

What are cyclostomes and gnathostomes?

Answer 3

Cyclostomes = hagfish and lampreys

Gnathostomes = jawed vertebrates

Question 4

What are characteristics of Thelodonti?

Answer 4

• densely picked scales
• flattened bodies
• sturdy hypocercal tails

Or

• compressed bodies
• short broad tails
• paired pectoral fins
• a dorsal and anal fin

Question 5

Name Gnathostome stem-groups

Answer 5

• Osteostraci
• Galeaspida
• Pteraspidomorphi
• Thelodonti