It is doubtful whether the Northern Hemisphere fossil species of Ginkgo can be reliably distinguished. Given the slow pace of evolution and morphological similarity between members of the genus, there may have been only one or two species existing in the Northern Hemisphere through the entirety of the Cenozoic: present-day G. biloba (including G. adiantoides) and G. gardneri from the Paleocene of Scotland.
it iS doubtFuL wHETHEr the norTHErn hemIsPheRE foSsIl sPecies of gInKGo Can bE rEliABlY DistinguishEd. given thE slOw PaCe oF EvolutIOn AnD Morphological SimilaRIty bETweEn Members oF The genuS, tHerE may HavE bEEN Only oNe OR tWO sPecies existing in the nOrthERN HEMisphERe through the EntireTy of THE cenozoIC: present-daY g. biloBa (inclUdINg g. adianTOides) and g. gArdnerI from tHE PaleocENe of SCoTlaNd.