My Inner Fish

For the past week, we have been watching a video series named "My Inner Fish" based on a book with the same title by Neil Shubin. We first watched part 1, which talks about the transition from water to land. We learned about Tiktaalik, a transitional organism. It also showed how our hand evolved and its relation to structures in other tetrapods. This links back to what we learned about homologous structures because our palms & fingers are descended from Tiktaalik's flipper-hands.

The second video was called "Your Inner Reptile", which was about the transition from ancient reptiles to mammals. We learned about the ancestors of mammals and how their lifestyle involved living underground, hunting, hiding from dinosaurs, and using whiskers. It also explained the gene "EDA" which controls organs including hair, nails, and glands. This relates to Unit 5 because the gene EDA causes proteins to be produced and determines the location of growth for many organs.

7. What was the "needle in the haystack" that they were looking for in the Canadian fossils? Why was it important?

They were looking for a transitional tetrapod fossil. The organism would have to fill the gap between lobe-finned fish and the early amphibian. It should have an about equal amount of fish and tetrapod characteristics to be the "needle" they are looking for. The reason it is so hard to find is because the chance of an organism from almost 400 million years ago fossilizing is very low and it probably won't be well preserved. Another challenge was the weather down there.

Source

24. How and why did hair first evolve?

We think hair first evolved as a sensory organ in early mammals. They would have been similar to modern whiskers, except the rest of the body was just covered in bare skin or scales.However, on the other parts of their body, did they just have bare skin, or did they have just scales? I wonder if they had any of these, than how did the hair spread down to the rest of the body? I'm guessing EDA, but we may never know until farther is known about this topic.