Rise of the fishes

Question 1

conodonts

Answer 1

• found as isolated mineralized toothlike ‘conodont elements’
• most abundant fossisls in palaezoic rocks
• elements form a complex three dimensional structure towards the head of the animal interpreted as a feeding apparatus

Question 2

What features did chordates have?

Answer 2

• A notochord
• Paired sensory organs
• Fins with fin rays
• V-shaped muscle blocks
  (chordate features)

Question 3

cyclostomes (hagfishes and lampreys)

Answer 3

• eel-like vertebrates with no jaws
• have keratinous teeth within the mouth that can be protruded out
• do not have a vertebral column around the notochord, but have cartilaginous skulls

Question 4

lampreys

Answer 4

• jawless fishes with a circular array of rasping teeth
• A notochord
• Vertebra-like structures
• An attached cartilaginous skull and gill arches
• Fin rays