Presentation is loading. Please wait.

Presentation is loading. Please wait.

Skeleton, Skin and Scales. Skull Evolutionary tendency Fusion of skull bones evolutionary time High # bones Low # bones.

Similar presentations


Presentation on theme: "Skeleton, Skin and Scales. Skull Evolutionary tendency Fusion of skull bones evolutionary time High # bones Low # bones."— Presentation transcript:

1 Skeleton, Skin and Scales

2 Skull Evolutionary tendency Fusion of skull bones evolutionary time High # bones Low # bones

3 Skull Neurocranium (brain case) Branchiocranium (endoskeletal arches, original gill arch supports) –Chondrocranium (original cartilagenous braincase) –Dermatocranium (dermal bones attached to skull) -Arches: -Mandibular -Palatine -Hyoid -Opercular -Branchial

4 Neurocranium

5 Branchiocranium

6 Mandibular Arch (cartil. & dermal origin) –Sharks Palatoquadrate Cartilage (top jaw) Meckel´s Cartilage (bottom jaw) –Bony Fishes Premaxillae, Maxillae, Supramaxillae (top jaw) Dentary, Angular (bottom jaw) Palatine Arch (cartil. origin)

7 Branchiocranium Hyoid Arch or Supensorium (cartil. Orig.) –Provides support and attachment to skull. lower jaw (Quadrate) opercular apparatus Opercular Arch (dermal origin) –Protects gills (Opercule)

8 Branchiocranium Branchial Arches (cartil. origin) –Support gills (Ceratobranchial & Epibranchial) –Help chewing (Pharingeal bones)

9 Lampreys

10 Sharks

11 Bony Fishes

12 Jaw evolution hypothesis

13 Viperfish mandible

14 Protrusible mouth (ascending process on premaxilla that slides along front of skull). premaxilla maxilla mandible

15

16 Jaw Suspension Evolution AMPHISTYLIC HYOSTYLICAUTOSTYLIC

17 Vertebral Column PrecaudalCaudal

18 Fins Pectoral Girdle –Not attached to vertebral column –Attached to Skull Pelvic Girdle –Not attached to vertebral column Caudal Fin –Protocercal, heterocercal, homocercal

19 Fins Median Fins –Sharks Ceratotrichia (dermal) Radials (cartil.)

20 Fins Median Fins –Bony Fishes Ceratotrichia (in larval stages) Lepidotrichia (dermal) Pterygiophores (cartil.)

21 Soft raysTrue Spines soft segmented branched bilateral hard and pointed unsegmented unbranched solid

22 Skin

23 Scale Types Placoid –Sharks, rays and chimaeras –dermal and epidermal origin –Irrigated pulp cavity + dentine + vitrodentine –homologous to vertebrate teeth Cosmoid –Lungfishes –originated by fusion of placoid scales –Two bone layers + cosmine + vitrodentine

24 Scales Ganoid –Sturgeons, paddlefish and gars –modified cosmoid scale –Two bone layers + dentine + ganoine Cycloid and Ctenoid –Bony fishes –evolved from ganoid scale (loss of ganoine) –Almost all dermal –Overlapping (shingle-like)

25 Scales

26 PLACOIDGANOIDCOSMOID

27 CTENOID CYCLOID


Download ppt "Skeleton, Skin and Scales. Skull Evolutionary tendency Fusion of skull bones evolutionary time High # bones Low # bones."

Similar presentations


Ads by Google