1 - Lecture 33 Notes

Gill arches added and teeth acquired chordate

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Unformatted text preview: lter feeders Vertebrates have colonized a wide variety of environments †† † = two groups of extinct fish Vertebrates have colonized a wide variety of environments †† † = two groups of extinct fish Chordate phylogeny including two extinct groups of fish † † 1: Cranium 2: Vertebrae 1 2 Ostracoderms: heavily armored (bony), extinct jawless fish •  probably filter feeders and scavengers •  radiated in Silurian and Devonian (~400 mya) Chordate phylogeny including two extinct groups of fish † 1 2 3 † 1: Cranium 2: Vertebrae 3: Bone And then, a remarkable thing happened: JAWS EVOLVED Gill arches: cartilaginous gill supports Anterior gill arches became modified as bony jaws Additional gill arches added, and teeth acquired Chordate phylogeny including two extinct groups of fish † 1 2 3 † 4 1: Cranium 2: Vertebrae 3: Bone 4: Jaws And then, a remarkable thing happened: JAWS EVOLVED And then, a remarkable thing happened: JAWS EVOLVED hSp://www.tumblr.com/tagged/baby%20teeth Placoderms: armor-plated predators with jaws and teeth-like structures •  first jawed vertebrates •  originated in Silurian, extinct by end of Devonian (360 mya) Some...
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