Question

1. Illustrate and discuss the concept of intermediate, or transitional, fossils, using Tiktaalik as an example. Finally, explain why transitional or intermediate fossils like that of Tiktaalik are so important for the study of evolution.

2. Define and illustrate the concept of homology using the vertebrate forelimb as an example. Next, explain why vertebrate forelimbs are so different in spite of their underlying structural similarity. Explain the significance of developmental homologies to our understanding of descent with modification. Now, illustrate and explain how DNA sequences are examples of homology between organisms. Finally, illustrate and explain how the level of DNA sequence similarity between organisms reveals their relationship through evolution.

Answer 1

Transition fossil: Fossils of an organism that shows an intermediate state between the ancestral form And that old the descendant form of a species is referred as the transitional special.

In easy words:

The middle form or the fossil has both the features of the ancestor and the descendant.

One example of such case is the Tiktaalik which is first discovered in Canada in 2004. This 'fish' was the first to explore the terrestrial living. They were an intermediate of a fish and an amphibians.

It has features like that of the fish- gills and fins which is the characteristics of a fish. But it also had a flat head Like that of a crocodile and they also had ribs. What made it more different from the fish is how it's neck was placed. Fishes don't have a functional neck but a Tiktaalik head was not connected to a shoulder which made the neck functional which is not the same for the fish. Fishes do not have a functional neck.

They lived in the water, they could have pribapro survived in the shoreline as it's frint fins made it difficult for Tiktaalik to walk in the land. So they lived mostly in the shallows.

These help in understanding the divergence in the evolution. Also, this Fossils shows the evolutionary relationship between organisms. And it helps in a way to prove that Darwinian theory is right.