Inner Fish Discussion Answers

Ella Aerts Period 5 Your Inner Fish Discussion Answers

Chapter 1 - Finding Your Inner Fish

Neil and his colleagues focused on rocks from 375 million years ago because fossils from 360 million years ago were amphibians with necks and four legs. However rocks that are 380 million years old looked more like fish we know today, with fins and scale. So, it made sense that they would find the transitioning fossils in rocks that was 375 million years old. Neil chose to look in sedimentary rocks, such as limestone, sandstones, siltstones and shales, because they form fossils gently since they generally are formed by rivers, lakes and seas. At first, they were looking for fossils in the Devonian rocks in Pennsylvania, but they did not have much luck since the rocks had too much exposure. So they found that the High Arctic of Canada was ideal because the rocks were 375 million years old, they were sedimentary and had little exposure.

Webbed fins, a flat head, a neck and scales on its

The hedgehog gene helps make a region of the body different from another region and is found in limbs. This gene is active in ZPA. Cliff Tabin, Andy Macmahon and Phil Ingham attached a molecule of the hedgehog gene to see where it was active in the chicken. They found that iw is active in the ZPA. If the gene didn’t turn on when it’s supposed to, then we’d have extra finger of our pinkie and thumb would look alike. Randy Dahn ran similar experiments on sharks and Skate He saw that the gene turns on at the same time as in chickens. Also it is turned on in the back of the fin aka the pinkey. When they treated it with a vitamin A, it turned the gene on in the opposite side of the fin as well. Later he took a hedgehog gene from a mouse and placed it between identical skeletal rods of a skate. The rods responded to the gene. Since the mouse is a mammal and its gene worked on the skate, it proves that all genes are build