Summarize how scientists use evidence from rock strata to create a geologic time scale and organize Earth's 4.6 billion year history. In your response be sure to include the following: How do they divide the time periods/events of the 4.6 billion year history?
Explain how they interpret rock age using relative dating principles
What are some examples of evidence they use from the rock strata?

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands

answer >   yes we do, women; have three holes, urethral opening(pee hole, vagina, and the women pee/girls pee out of the urethra like the men do; only they have a single opening to pee/ejaculate.   (sorry if i'm too forward with this, but this is for a biology class, isn't it? )

hope that !         : )