The Radiation of Osteichthyes, the Bony Fish: ray-finned fish; lobe-finned fish; limbed vertebrates
- Created by: ValentineDevil
- Created on: 21-02-19 11:36
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- The Radiation of Osteichthyes, the Bony Fish: ray-finned fish; lobe-finned fish; limbed vertebrates
- Diagnostics
- Extensive exndoskeleton ossification
- Endo and exo skeleton have succedded in vertebrate evollution
- Perichondral ossification: bone arising from precursor cartilage develops on surface of cartilage
- Endochondral ossification: bone develops from within cartilage mass as the cartilage template becomes degraded
- Endo: Cartilage bones e.g. vertebrae, ribs, limb bones
- Exo: Dermal bone e.g. skull roof bones, dentary, clavicle, gastralia, scale of fishes, osteoderm
- Membrane bone e.g. centra of teleosts, sesamoid, orbitosphenoid of the Amphisbaenia
- In osteichthyansthe neurocranium is a solid structure due to extensive ossification
- Neurocranium is articulated with the palatoquadrate via an articulation (basipterygoid process)
- Endo and exo skeleton have succedded in vertebrate evollution
- Rooted teeth
- Develop in dermal bones lining the margins of the mouth (upper premaxilla and mailla; lower dentary) as well as dermal bones that surround the primordial and embryonic upper palatoquadrate cartilage and lower Meckel's cartilage
- Close integration of between dentine and enamel, built by specific sets of cells
- Primitively 4-plated sclerotic ring
- Medial adductor muscles in lower jaw (muscles of inside jaw attached to skull)
- Since ancestor of ray fish... few bones have shifted very little, as their spatial relationship stays relatively the same
- Conserved bone pattern in skull roof
- Large bones in skull and pectoral girdle
- Bony fin rays
- Bony, bilaterally paired, segmented
- Originate from modified scales?
- usually composed of bone, but in early osteichthyans dentina dn enamel were also present (segmented and appear as a series of stacked disks)
- Genes coded for production of certain proteins; it is suggested that the evolution of the tetrapod limb is related to the loss of these proteins
- Support medians fins
- Swim bladder (some fish; others it is now a lung)
- Lungs were added to pre-existing gills
- Swim bladders originated from modified lungs
- Operculum
- Protects gill chamber
- Various scale types
- Ganoid (gar; bowfins, bichirs, sturgeons)
- Heavy and inflexible; rhomboid; peg and socket articulations; little or no overlap
- Inner layer of scale is lamellar bone; a cosmine (dentine) layer is on top, then an enamel-like ganoine, which is then covered by ganoine
- Cycloid (salmon; and roaches)
- Leptoid
- Grow through peripheral addition of concentric layer
- Thin, flexible
- Ctenoid (bass; perches, gobies)
- Leptoid
- Ctenoid (bass; perches, gobies)
- Placoid (shark)
- Leptoid
- Grow through peripheral addition of concentric layer
- Thin, flexible
- Ganoid (gar; bowfins, bichirs, sturgeons)
- Haemal arches protect blood vessels ventral to notochord (which isn't ossified). Ribs protect notochord in trunk region. Neural arches protect nerve chord dorsal to notochord
- Extensive exndoskeleton ossification
- Supraneurals may extend from neural arches.
- Intercalary ossifications form between neural or haemal arches
- Diagnostics
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