Osteichthyans

Question 1

Actinopterygii

Answer 1

single dorsal fin, scales with complexly layered ganoine, everted cerebral hemispheres. Ray finned fishes. Basal elements of pectoral fin enlarged. Medial fin rays attached to skeletal elements that do not extend into fin, unique interlocking system

Question 2

Actinopteryi

Answer 2

basals in the paired fins reduced, lung has become single and dorsal, pulmonary circulation reduced or lost (circulation to lung) - essentially becomes a swim bladder

Question 3

Acipenseriformes

Answer 3

Chondrostei; sturgeons and paddlefishes. They revert, they lose their endochondral ossification (whole skeleton is cartilage) They turn their lung into a gas bladder. Presence of the five longtitudinal rows of bony scutes along the trunk. Presence of long, stout, fin spine along the leading edge of the pectoral fin. Caviar eggs

Question 4

Neopterygii

Answer 4

basals and radials in paired fins are reduced (even more), form a homocercal tail (caudal fin with nearly symmetrical lobes), mobile maxilla. Holostei and Teleostei. Upper lobe of caudal fin containing axial skeleton reduced in size to produce a nearly symmetrical fin. Upper pharyngeal teeth consolidated into tooth-bearing plates (plates stuck to the upper surface of pharynx –on to base of of gill bars

Question 5

Telostei

Answer 5

stiffened tail fin within the homocercal tail (uroneural bones) i.e. modified neural arches in tail to make superficially symmetrically stiff tail, mobile premaxilla, mobile pharyngeal jaws, lung turned into a gas bladder. Vomer is single and median (in the palate). Frontal bones in head are expanded posteriorly

Question 6

Osteichthyans

Answer 6

endochondral ossification, bony operculum, dermal marginal mouth bones with rooted teeth, unique pattern of ossification of dermal bones of pectoral girdle, lepidotrichia on their fins, presence of lung or swim bladder derived from gut, medial insertion or adductor mandibulae on lower jaw

Question 7

ganoine

Answer 7

layered enameloid

Question 8

What are the bones involved in forming a homocercal tail?

Answer 8

hypural bones, uroneural bones, and urostyle

Question 9

Polypteryiformes

Answer 9

birchirs - are all in Africa. Have paired lungs which attach to the esophagus with a glottus. Obligate air breathers. Lungs are very vascularized however they are smooth sacs, no alveolar tissue. Rhombic ganoid scales, unique dorsal fin spines, facial bone fusion, unique pectoral fin structure.

Question 10

Osteoglossomorpha

Answer 10

bony tongues and moon eyes. toothed or bony tongue. Primary bite between parasphenoid and tongue. Paired tendon bones on the second hypobranchial, or second hypobranchial and basibranchial. Teleost.