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Appendicular Skeleton

Appendicular Skeleton. Appendicular Skeleton. Girdles : Pectoral (anterior) Pelvic (posterior) Fins or limbs First appears in Gnathostomes with …. Ostracoderms ?. Fish Girdles. Pectoral girdle attached to skull Pelvic girdle in body musculature or attached to …. Tetrapod Girdles.

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Appendicular Skeleton

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  1. Appendicular Skeleton

  2. Appendicular Skeleton • Girdles: • Pectoral (anterior) • Pelvic (posterior) • Fins or limbs • First appears in Gnathostomes with … Ostracoderms?

  3. Fish Girdles • Pectoral girdle attached to skull • Pelvic girdle in body musculature or attached to …

  4. Tetrapod Girdles • Transfers weight of axial skeleton to … • Pectoral girdle: • Made up of dermal andendochondral bone • Provide attachment points for musculature that connects … • Pelvic girdle: • Made up of … • Attaches to …

  5. Fins • Pterygiophoresconnect to … • Fin rays extend from pterygiophores (radials) Fig. 9.2

  6. Limbs • Tetrapod limbs have same pattern of … Fig. 9.2

  7. Fins • Metapterygial axis defines … • Archiptergial – symmetrical central axis • Metapterygial – asymmetrical axis Fig. 9.3

  8. Why have paired fins?

  9. Why have paired fins? Fig. 9.3

  10. Origin of Paired Fins • Fin-fold theory – arose from within paired, but continuous … Fig. 9.6 Fig. 9.5

  11. Origin of Paired Fins • Fins stiffened by … • Additional stability from: • Inward extension of … • Fusion of basals at midline  Fig. 9.5

  12. Origin of Paired Fins • Support from Hoxgene research • Duplication of… “Rescued” knockout mice Minguillon et al. 2009. PNAS

  13. Origin of Paired Fins • One duplicate influenced … • One duplicate influenced … • Sonic hedgehog carried to early tetrapods and… Fig. 9.5

  14. Fins to Limbs Fig. 9.8

  15. Fins to Limbs • Major axis in tetrapods just bent … • Digits on … Fig. 9.8

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