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4 Cards in this Set
- Front
- Back
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Two competing hypothesis for the interrelationships of craniates |
Cyclostome hypothesis ( means round mouth ) / round mouth hypothesis - hagfish and lamphreys more closely related than vertebrates (supported by molecular data ) Vertebrate hypothesus- lamphreys more related to jawed vertebrates than to hagfish |
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Hagfish lampreys differences |
H=direct development L= larval stages , metamorphosis H= 1semicurcular canal L= 2 Not elaborate skulls, slightly elaborate Adult heart without nervous regulation , with No fully developed vertebrate, simple No neuromasts on central line, neuromasts Nasal duct opens into pharynx,blind punch 1,2 external gill pores, 7 slits |
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Diagnostic features of lamphreys and jawed vertebrates |
Elaborate skulls- dermatocranium ,neuro cranium splonchioceaniun
Vertebrate
Extrinsic eye muscles
Radial musculature in fins- fan-like arrangement Neuromasts- apart of the lateral line system , allows to detect movement and vibratii s in the water
Regulation of heat by nervous system
At least two semicircular cannals
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Development of hagfish vetebrate |
Early embryonic stages -Medial ventral somites -( embryonic segments) differentiate - mesenchymal cells -some migrate to ventral part of notochord- differciate into cartilagenius nodules- which would develop into vertebrae |
