Postcranial (Appendicular)

Question 1

Appendicular skeleton

Answer 1

fins or limbs and girdles

Question 2

Fin Girdles

Answer 2

Girdle –> Pterygiophores (Basals, Radials) —> Fin Rays

Question 3

Paired Fins: Ceratotrichia

Answer 3

Elasmobranchs: slender filaments of keratin-like protein

Question 4

Paired Fins: Lepidotrichia

Answer 4

Osteichthyans: tiny cartilagnious or bony elements

Question 5

Gill-Arch Hypothesis

Answer 5

Paired fins are modified gill arches
- girdle arose from gill arch
- pterygiophores arose from gill rays

Question 6

Fin Fold Hypothesis

Answer 6

Paired fins are derived from lateral folds in body wall
Girdles were formed by fusion of basals

Question 7

Archiptergyial Fin

Answer 7

Symmetric midline axis

Question 8

Metapterygial FIn

Answer 8

Asymmetric axis
- likely ancestral for limbs

Question 9

Limb part names

Answer 9

Girdle –> Stylopodium–> Zeugopodium–> Autopodium

Question 10

Pectoral Girdle Characteristics

Answer 10

• endochondral + intramembranous (dermal)
• positioned in muscular sling in tetrapods

Question 11

Pelvic Girdle Characteristics

Answer 11

• endochondral
• fused to vertebral column via sacrum in tetrapods

Question 12

Embryonic Development of Pectoral Girdle/Fin Rays/Pelvic Girdle

Answer 12

Pterygiophores + tetrapod limbs + pectoral girdle (endochondral part) + pelvic girdle: Somatic mesoderm
Fin Rays: Somites ( likely modified scales)
Pectoral girdle (intramembranous part): Somites (likely modified osteoderms)