BISC 316 Lecture Notes - Lecture 7: Shoulder Girdle, Sonic Hedgehog, Branchial Arch

• School: Simon Fraser University
• Department: Biological Sciences
• Course: BISC 316
• Professor: Tammy Mc Mullan

Document Summary

Three major adaptations: jaws, paired fins, vertebrae. Ostra(cid:272)oder(cid:373)s (cid:862)fi(cid:374)s(cid:863) derived fro(cid:373) der(cid:373)al ar(cid:373)our; solidly atta(cid:272)hed to (cid:271)ody: stabilizers, new fossil with paired anal fins. Paired fins present in acanthodii and placoderms. Acanthodii 2 rows of spines with attached tissue flaps; some had internal skeleton of cartilage. Placoderms: pectoral and pelvic fins, some were narrow based (similar to sharks, can be tucked into body to reduce drag. Internal skeleton of cartilage and flexible fin rays. Theories of the origin of paired fins: gill arch hypothesis, fin-fold hypothesis, fin spine hypothesis, gill-arch hypothesis. Paired fins and girdles arose form gill arches: girdles from gill arch, fin from gill rays. Presence of dermal bone in pectoral girdle. Embryological origin of girdle and gill arches. Predict gill arch and fin rays should have common mechanism that have same functional roles. Gnathostome fin and limb bud growth directed by shh (sonic hedgehog) and fgf (fibroblast growth factor(