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| arose in devonian, silurian fossils only scales, no teeth; paleozoic radiation, early sharks terminal mouoths, many w/ functionally symetrical tails, by carbonieferous 60% fish species sharks |
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| early sharks terminal mouoths, many w/ functionally symetrical tails, by carbonieferous 60% fish species sharks |
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| super order w/ modern sharks, ventral mouths (expanded muscle attachement b/w jaws and neurocranium), protrusible upper jaw: palatoquadrate separated from braincase,hymandibular connector:hylostylic suspension; jaws move ahead of snout, acceleration of bite, better bite angle; calcification of centra; ceratotrichia:horny fin ray elements composed of protein, more flexible for maeuverability |
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| multiple gill slits, usually 5 |
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| subterm or ventral, nasal openning |
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| 800 species, less than half "shark like", most carchariniformes, rest in rajiformes |
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| large, piscivorous predators |
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| most specialized as piscivorous predators, usually lower teeth spikey, upper teeth blade like; few filter feeders; hard shelled invert feeders: teeth from multiple rows form pavement |
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| relatively large brains; very good olfactory capabilities; good vision(particularly night vision), hearing; electroreception: location of prey in near range, orientation in migration |
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| relatively large brains; very good olfactory capabilities; good vision(particularly night vision), hearing; electroreception: location of prey in near range, orientation in migration |
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| resting rate 1/3-1/2 of bony;slow growth, late age at maturity, long lifespan |
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| low fecundity; direct development, slow; three repro modes:ancestrally, oviparity; young retained, nourished w/ yolk sac:ovoviviparity(in some oophagy or embryophagy); viviparity, w/ nourishment from mother via placenta or uterine milk |
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