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Appendicular Skeleton Appendages and supporting girdles.

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Presentation on theme: "Appendicular Skeleton Appendages and supporting girdles."— Presentation transcript:

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 Pelvic fin Pectoral fin Caudal fin Dorsal fins Anal fin




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

62 Pelvic fin Pectoral fin Caudal fin Dorsal fins Anal fin

63 Fish tails Heterocercal Homocercal Diphycercal

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