After doing some or most of the reading and work for the week, select one of the questions below as a starting point for your collaboration this week. Do some research if you need, add to what you may have learned from the book or lab, and share. Select a question to explore and write a paragraph or two: What are the characteristic features of the chordates? What is the structural advantage of the notochord in the human embryo? Be sure to compare the notochord with the corresponding structure in adults. What can be inferred about the evolution of the cranium and vertebral column from examining hagfishes and lampreys? Describe the functions of the three extra-embryonic membranes present in amniotic eggs. What characteristics differentiate lizards and snakes? Explain why birds are thought to have evolved from theropod dinosaurs. Describe three characteristics of the mammalian brain that differ from other vertebrates. Describe three unique features of the mammalian skeletal system. Why is it so difficult to determine the sequence of hominin ancestors that have led to modern Homo sapiens ?