Carnegie Institution of Washington, 1938, Rarity of pre-Cambric fossils: Pan-American Geologist, v. 70, p. 228-229. Authors Carnegie Institution of Washington Publication Date 1938 Citation Pan-American Geologist, v. 70, p. 228-229. State AZ Province CP County CN MO Keywords Paleontology Proterozoic More Keywords Paleontology, Proterozoic, AzGeoBib RefNum 1655