Name and briefly describe the three main models, or hypotheses, of primate origins?

Hello, I have an Anthropology class assignment needs help. You need to write at least one paragraph per one question. Darwin had very few fossils to support his theory of evolution by means of natural selection when he published . Why are fossils considered essential for the study of biological evolution? What can be learned by studying fossils? Name and briefly describe the three main models, or hypotheses, of primate origins? What critiques or criticisms do you have? Please follow the instructions carefully and finish the work before due. Thank you.