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Appendicular Skeleton

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Appendicular Skeleton

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    1. Appendicular Skeleton Appendages and supporting girdles

    3. Pectoral Girdle Function

    4. Pectoral Girdle – Replacement bones Coracoid (Epicoracoid) Scapula Suprascapula

    6. Pectoral Girdle – Membrane bones Clavicle Cleithrum Supracleithrum Postcleithrum Posttemporal Interclavicle (Episternum in tetrapods)

    8. Pectoral Girdle Glenoid fossa on scapula for limb attachment

    9. Key Point What trend do you see as you look at the overview of pectoral girdles?

    11. Pectoral Girdle - Placoderms First to have a pectoral girdle

    12. Pectoral Girdle - Chondrichthyes Cartilage No dermal elements Coracoid, scapula, suprascapula (scapulacoracoid) Not connect to axial skeleton, but fused at midline

    14. Pectoral Girdle – Bony fish Membrane bones Clavicle, some have interclavicle Cleithrum – largest Supracleithrum, postcleithrum Posttemporal – anchors to skull

    16. Pectoral girdle – bony fish Replacement bones Coracoid Scapula

    18. Pectoral Girdle - amphibians Membrane bones Reduced Lose posttemporal Early amphibians gained an interclavicle as a brace

    19. Pectoral Girdle - amphibians Replacement bones Coracoid Scapula and suprascapula

    21. Pectoral Girdle - amphibians Urodeles have no membrane bones, including clavicle Anurans have clavicle, no interclavicle and usually no cleithrum

    22. Pectoral girdle - Reptiles Stem reptiles & synapsids Many membrane bones present Most replacement bones present New posterior coracoid present

    24. Pectoral girdle - Reptiles Modern reptiles have scapula, coracoid, sometimes clavicle, sometimes interclavicle Crocodiles have reduced clavicle Turtles have interclavicle fused with shell Snakes have no girdle Lizards have a significant clavicle and interclavicle

    26. Pectoral Girdle - birds Furcula (2 clavicles plus interclavicle) Scapula – bladelike Coracoid (anterior or pro-) which articulates with sternum

    28. Pectoral Girdle - mammals Monotremes similar to stem reptiles Clavicle in most Scapula Coracoid process from posterior coracoid Spine is new Acromion process articulates with clavicle (not new)

    33. Pelvic Girdle Stability, encloses pelvic cavity organs In tetrapods, it has three parts called the ilium, pubis and ischium When these three bones fuse into one, the fused bone is the innominate or coxal bone Acetabulum is the socket for the thigh Symphysis in all but birds Replacement bone

    36. Pelvic Girdle - Fish Pelvic plate or symphysis

    38. Pelvic Girdle - amphibians Pubis Ilium (long & slanted in frog) Ischium

    40. Pelvic Girdle - Reptile Sacroiliac joint is stronger and broader for more muscle attachment and stability

    42. Pelvic Girdle - birds Synsacrum – Ilium is braced against fused vertebrae No symphysis WHY??

    44. Pelvic girdle - mammals Epipubic bone in marsupials is unique for pouch support

    46. FINS Steering, rolling, braking, stabilizers, forward & vertical movement

    47. Fin structure Skin epidermis covering Fin rays in dermis Lepidotrichia (scale-hair) bony dermal scales, segmented Ceratotrichia (horn-hair) cartilaginous unsegmented rays

    49. Fin Structure Skeletal base (cartilage or bone) for support Pterygiophores (bearing fin) Basals are proximal Radials are distal

    51. Paired Fins Absent in agnathans Some in placoderms & acanthodians Chondrichthyes Fin Fold Fins – very broad based

    53. Paired Fins Bony fish Actinopterygii has ray fins, very flexible with thin base Sacrcopterygii has fleshy muscular base Dipnoi has lobe fins Crossopterygii has lobe fins that are called fringe fins & have pterygiophores on one side of fin axis

    54. Osteichthyes skeleton

    58. Origins of fins From acanthodian spines? From fleshy folds? From gills?

    59. Median fins – Dorsal and Anal fins

    60. Dorsal and Anal Fins Function for rolling, defense, display Location – rests on vertebral column Variations among groups

    61. Caudal fins Heterocercal Hypocercal Diphycercal Homocercal Teleosts Neural and Hemal arch for support Bony sheath for notochord

    63. Fish tails

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