Paired fins/webbed processes strengthened by internal fin rays.

Pterygiophores strengthen proximal fin (basal).

Basals articulate with the girdle.

fish=lepidotrichia=bone/cartilage.

2 Sets of paired fins: pectoral and pelvic for movement and stability.

1. Paired fins arose within paried continuous sets of ventrolateral folds in the body wall.
2. Folds specialize into pelvic and pectoral
3. Folds stiffened by pterygiophores.
4. Basals extend inward and fuse across the midline forming girdles for more stability.
5. Dermal bone added to pect girdle for strength.

Chiridium.

3 regions

1. Stylopodium: most proximal. Single skeletal element.
2. Zeugopodium: 2 internal elements
3. Autopodium: many bones

Hand

metacarpals(palm)->carpals(wrist)

Foot

metatarsals(above toes)->tarsals(toes)

Shoulder region derived from dermal bone and cartilage (endochondral)

U shaped in fish and attached to skull.

Loss of skull attachment in tetrapods.

No direct attachment to V.C. ->no transmission of sudden impacts to the skull.

"muscular sling"

Serves as a brace for endoskel component and area for muscle attach.

Protects heart.

Fussion/enlargement of basal pterygiophores.

Fin muscles attach here.

No dermal bone.

Exclusively endochondral.

Arose from pterygiophores in support of the fin.

Direct attachment to V.C. (vs. no attachment in Pectoral Girdle)

Fish: single element.

Tetrapods: 3 fused elements (ilium, ischium, pubis)

Lateral movement (fish, amphibians, reptiles)

->initial sprawling of limbs (early tetrapods)

->limbs drawn under the body (later tetra)