Tonian microfossils from subsurface shales in Botswana Knoll, Andrew H. ; Germs, Gerard J. B. ; Tankard, Anthony ; Welsink, Herman Abstract Publication: Precambrian Research Pub Date: August 2020 DOI: 10.1016/j.precamres.2020.105779 Bibcode: 2020PreR..34505779K