End of muscle block secretes calcium into space

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Unformatted text preview: egments). end of muscle block secretes calcium into space between blocks remnants of notochord persist as inter-vertebral discs cushion your bone two muscle blocks contribute to a single vertebra Ostracoderms: heavily armored, extinct jawless fish with bony plates in the skin, including around the gills •! probably filter feeders and scavengers •! radiated in Silurian and Devonian (~400 mya) JAWS EVOLVED from bony plates in the skin that held the gill slits open. Gill arches: cartilaginous gill supports Anterior gill arches became modified as bony jaws Additional gill arches added, and teeth acquired Placoderms: armor-plated predators with jaws and teeth-like structures •! first jawed vertebrates •! originated in Silurian, extinct by end of Devonian (360 mya) Some placoderms...
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