EEB267H1 Study Guide - Final Guide: True Toad, Paleozoic, Ankle
9 Apr 2015
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Step #2: tiktaalik: articulation between upper and lower arm bones-elbow joint, articulations between lower arm bones and carpals-flexible wrist, able to do push ups. Shoulder, humerus, ulna and radius are very robust: nostrils moving upwards. Perhaps lived in shallow waters and lifted head to breath-mobile neck. Step #3: acanthostega: fins are gone and have real limbs-hands, feet, and eight fingers and toes, pelvis is fused with three bones-stable and strong to support development of legs, no more fins. Tail is still big caudal fin- acting like salamander in water: wrist and ankle are not complete-arms and legs are not too flexible. Too much salt is toxic as it infers with the transmission of nerve impulses and causes increased blood pressure, etc: osmosis: the flow of water from an area of low to high solute concentration. Marine problem: more salt in the sea than in the organism so the organism is the dilute solution.
