1. Neil Shubin and his colleagues chose to focus on 375 million year old rocks in their search for fossils because at 365 million year old amphibians roamed the earth and whole fish are found to be 385 million years old. They also selected sedimentary rocks because these are most suited to preserve fossils. At 375 million year old, the Devonian age, there are three areas with fresh water stones, Greenland, which has already been excavated, eastern North America, where they Shubin already worked on, and the Arctic which was unexplored. This is how Neil Shubin’s research team settled on what type of rocks to investigate.
2. The Tiktaalik shows the connection between fish and land animals, which confirms the major paleontological…show more content… 3
1. One of the developmental manipulation experiments, performed by Mary Gasseling, found if you removed the developmental pinky and place it on the other side under the first finger the wing develops fully but with a full set of duplicated digits. When this experiment was formed on other animals, such as mice and sharks, they produced the same results as in the chickens. This is significant because it validates the “inner fish” theory by confirming the existence of a strong connection between various life forms.
2. First discovered in fruit flies, the hedgehog gene controls the differentiation bone structures. This draws comparison to ZPA in chickens, which might have been a contributing factor for scientists to look for the hedgehog gene in other animals. Scientists found this gene in the chicken’s ZPA which when activated the pinky and thumb develops. In human embryos if the sonic hedgehog gene is not activated in the eight week the thumb and pinky may be identical or the child may have extra fingers.
Ch. 4
1. Teeth are the hardest part of the human body because the enamel contains a high concentration of hydroxyapatite. The level of hydroxyapatite is higher in teeth than any other bones in the body. Due to the hardness of the teeth allow them to be the best preserved as
