graptolite zone笔石带
Graptolite colony笔石群
graptolite zonation笔石分带
Graptolite Reflectance笔石反射率
graptolite reflectivity笔石反射率
graptolite bed笔石层
black graptolite黑色笔石
graptolite grap笔石
N（名词） any extinct Palaeozoic colonial animal of the class Graptolithina, usually regarded as related to either the hemichordates or the coelenterates: a common fossil, used to determine the age of sedimentary rocks 笔石