The theory of evolution suggests a "principle of floral (plant) succession" to complement Smith's principle of faunal succession. Why do you think Smith relied primarily on faunal fossils rather than floral fossils in his stratigraphic mapping?

 

Why do you think Smith relied primarily on faunal fossils rather than floral fossils in his stratigraphic mapping?

There are conditions necessary to preserve fossils and these are rapid burial and possession of hard parts. Identification of plant fossils is hard in stratigraphic mapping because plants have only few hard parts thus they are not often preserved. Also, plants only evolved in the Ordovician so the Cambrian plant fossils are difficult to distinguish, unlike the animal fossils which have hard parts and proliferated in the Cambrian making them easier to preserve and distinguish from other animals. 

(I do not know if you already know the words Cambrian and Ordovician, but basically these are geologic periods in the Paleozoic era and Cambrian (542 million years ago) is older than Ordovician(486 million years ago))