NSCI 2041 Study Guide - Midterm Guide: Branchial Arch, Haemal Arch, Shoulder Girdle
19 Dec 2016
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Document Summary
Axial skeleton - cranial bones, vertebral column and ribs. Appendicular skeleton - limbs and girdle (pectoral and pelvic) Cranial skeleton a composite of 3 different sources. Bones from the dermal bone, originating in body armor of early fishes" integument (dermatocranium) Evolution from bones of first branchial arch in sharks and bony fish (same with hyoid) New research suggesting this evolved from armored fish (zhu 2016) Branchial arch i much reduced in reptiles and birds giving rise to 2 middle ear bones (malleus and incus) Reduced branchial arch ii leading to 3rd middle ear bone, stapes. Came from andrewsarchus, became early marine predators when the niche was vacant. Right whales: skim water filtering as they travel (baleen) Fin whales: pleated throat to expand and take in massive gulps of water (elastic mandibular symphysis so they can open up) Frontal and parietal bones much reduced, as nostrils move back onto top of skull in modern whales.
