Upon closer inspection, you find fossil samples B and C in the same stratigraphic unit as sample A. Sample B Sample B Sample C Sample C Photo credit: Terry Swanson What invertebrate index fossil group does sample B belong to? Select] What invertebrate index fossil group does sample C belong to? Select] Before leaving you find even more fossils in the same layer, pictured below. Photo credit:focsicra.com) What is the name of this index fossil group? [ Select Use figure 7-4 to complete the following statement. This layer must be older than or from the Select V period and younger than or from the Select period (Hint: think about the presence of all of the fossil assemblages found in this rock layer).