Orgin Of Paired Fins

Question 1

Archipterygial fin

Answer 1

In which the metapterygial stem runs down the middle of the fin and Endoskeletal radials project outward to support the PREAXIAL (anterior) and POSTAXIAL (posterior) sides of the fin evenly

Question 2

Metapterygial fin

Answer 2

Metaptyergial stem of basal is located posteriorly

Radials project into preaxial part derrma fin rays extend from the ends of the radius to the edges of fin

Question 3

What are the two fundamental types of fins that developed in gnathomstomes from 2 different arrangements of the metapterygial stem (chain of endoskeleton basals)

Answer 3

Archipterygial fin

Metapterygial fin

Question 4

Evolution and significance of appendages of gill arch theory

Found in somepresent day lungfish

Answer 4

(1) the appearance of a posterior pelvic girdle distantly placed from all the gill arches (2) presence of dermal bone and pectoral girdle (3) different embryologies of pectoral girdle and gill arches

Question 5

Fin-fold theory 329

Answer 5

Paired fins arose within a paired but continuous set of ventrolateral folds in body wall that were siffened by a transverse series of endoskeletal pterygiophores, proximally the basals and distally the radials
Additional stability came from the inward extension of basals and their there fusion across midline to produce supportive girdles
Dermal bone later added to pectoral girdle to strengthen paired fina further

Question 6

Supporting evidence

Answer 6

Pg 331