Scientists have debated the evolution of three life forms: reptiles, birds and dinosaurs. after many years of reviewing fossil records scientists proposed the evolutionary relationship seen above in the cladogram. using radiometric dating scientists added a time frame for the evolution of the animals within the model. based on this new information, what prediction can we make about the animals represented here? mya refers to millions of years ago. a) dinosaurs were the last to evolve among these groups of animals. b) crocodiles are the most highly evolved of the animals represented here. c) dinosaurs lived and became extinct before the arrival of lizards and snakes. d) turtles were the first group of animals to branch off in this tree of animals.

D) Turtles were the first group of animals to branch off in this tree of animals.

Turtles were the first group of animals to branch off in this tree of animals. According to the tree, the animals share a common ancestor. The first branch shows that what we call a speciation event occurred, resulting in two lineages. The first group of animals to result were the turtles. All the other animals are on the other branch. This does not indicate that any group is more highly evolved than the other.

americans began to notice growing differences between the northern and southern sections of the country. there were more people living in cities in the north, which made it more urban. more people lived on farms in the south, which made it more rural. while many people were farmers in the northern states, there were now other ways to make a living, such as working in mechanical cotton gins factories manufacturing cloth, tools and other goods. people in the north supported high tariffs on goods imported from europe because the extra cost encouraged people to “buy american” instead. in the southern states, planters did not like tariffs because they sold most of their production to europe and bought their tools from there as well. southerners believed the protective tariff was something that only northern factory owners keep their profits high. so the southern politicians came up with an idea. they would opt out. they would simply ignore the protective tariff. it was ‘null and void’ in south carolina. the state would not collect the taxes on goods imported into south carolina, no matter what the president said they had to do. this decision led to the nullification crisis.