At the beginning of the Trichechus Manatus life the population was very small. The species then separated into Trichechus Deepusfatous and Trichechus Skinitious. The cause of the event was because the Manatee was not getting enough food so half of the population made their way to the deep parts of the sea, and began eating seaweed instead of their regular diet. They became fat because they needed the extra warmth and they were able to become fat because they had enough food. The other half of the population stayed near the coast and that population became very slim, they didn't have a lot of food because of the ice age and it was warmer.The fatter population became extinct because when they returned to the coastal waters, their offspring were thinner because they didn't need as much fat. The thinner population made it because the weather became warmer at the coast, and the plant life was flourishing.