Fossil as resourceType instead of material type

[smrgeoinfo]

I suggest that 'fossil' should be a resourceType. The sampledFeature for the fossil is a species. The fossil 'occurs in' a geologic formation at a site. A material fossil is 'composed of' some material, but fossil is not a material, and a fossil is not collected with the intention of sampling a material (except as it relates to the fossil). Fossil should not be a material type. Early versions of GeoSciML attempted to model material fossils as a material type, but this proved unworkable. The current version (OGC standard) 4.1 does not include a class specifically for fossil, but represents material fossils as a particle type, and trace fossils or molds as a kind of geologicStructure (analogous to sedimentary structures).