This is a huge area of discussion, therefore, you must be very selective of your topic, and write succinctly and to the point. For example, you may want to choose the theme of "reproductive strategies" of fishes, amphibians, reptiles, birds, and mammals, or you may choose "locomotion", "environmental adaptations", etc etc etc - the list is endless. I am interested in reading your specific interest in evolutionary biology.
Throughout the millions of years of evolutionary progress, the human being, a mammal of great intellect came to be. But, it wasnt always that way, from the Cambrian times forward, we have been evolving, species by species, through the ability to physically, physiologically, and behaviorally change and adapt to the environment around us. As the environment changed from hot to cold, wet to dry, so did the species that lived in those areas. For those who could not adapt in their environment, they either moved on or died.
Through the ages, we went from jawless and cartilaginous fishes all the way to amphibians, reptiles, birds, mammals, and finally to human beings.
The earth experienced its first vertebrate in the Cambrian times. These vertebrate animals were of two different kinds of fishes, some with jaws and others without. Of the jawless fishes, we have ostracoderms, a small fish with a notochord and a cavity for the brain. Their bodies contained dentin, a material found in teeth today. Thus, we have a marker for the long evolutionary trip through history! The ostracoderms were simply bottom feeders, living in complete submersion of water, eating and nourishing themselves through filters. They attained food by attaching themselves to the food and eating from it in a filter-like method of sucking the food down and digesting it from there. The lamprey and the hagfish had a unique...