What is the diffrence between first cousins and second cousin?

The deserts of the sahara and australia are associated with

Which of the following must be true for a fossil organism to be useful as an index fossil? a. the fossil organism must be widespread geographically. b. the fossil organism must be abundant. c. the fossil organism must be limited to a short span of geologic time. d. all of the above.

Name the tissue types that form the wall of each organ in questions 7-10