- gabbii, Penitella
- Gablonzeria major
- Gafrarium divaricatum
- Gaillonella sulcata
- Galeoastraea amabilis
- Galeocerdo, genus
- Galeocerdo aduncus
- Galeodea apta
- Galeodea trituberculoides
- Galium kinuta
- Gall midge
- galloprovincialis, Mytilus
- gamoensis, Biwamelania
- gamoensis, Semisulcospira
- Gampsocleis, genus
- garoensis, Abies
- Gastropod
- Gastropoda, class
- Gaudryceras, genus
- Gaudryceras denseplicatum
- Gaudryceras (Gaudryceras) denseplicatum
- Gaudryceras (Gaudryceras) hamanakense
- Gaudryceras hamanakense
- Gaudryceras (Neogaudryceras) tenuiliratum
- Gaudryceras striatum
- Gaudryceras tenuiliratum
- Gaudryina ishikiensis
- Gaurodytes, genus
- Gavia stellata
- Giant cleftclam
- Giant isopod
- Giant knotweed
- Giant salamander
- Giant slipper limpet
- Giant triton
- gibba var. linearis, Pinnularia
- gibberula, Rhopalodia
- gibbosulum, Romaleon
- Gifuella amicula
- Gifuelloides larga
- gigantea, Helcion
- gigantea, Leucotina
- gigantea, Meekella
- gigantea, Nipponoclava
- gigantea, Scacchinella
- giganteum, Coelogasteroceras
- giganteum, Umbonium
- giganteus, Gigantocapulus
- giganteus, Megaloceros
- giganteus, Mytilus
- Gigantocapulus giganteus
- Gigantoproductus, genus
- gigas, Crassostrea
- gigas, Magallana
- gigas, Ostrea
- gilgiana, Salix
- gilgiana, Salix miyabeana
- gilva, Quercus
- Ginebis, genus
- Ginebis argenteonitens
- Ginebis argenteonitens hirasei
- Ginebis convexiuscula
- Ginebis crumpii
- Ginebis japonica
- Ginkgoaceae, family
- Ginkgoidium nathorsti
- Ginkgoidium nathorstii
- Ginkgoites, genus
- Ginkgoites digitata
- Ginkgoites digitata var. huttoni
- Ginkgoites huttoni
- Ginkgoites huttonii
- Ginkgoites pseudoadiantoides
- Ginkgoites sibirica
- Ginkgophyta, phylum
- Girdled lizard
- Glabratella opercularis
- Glabropilumnus, genus
- glaciale, Buccinum
- Glauconia, genus
- glaucum, Acer mono
- glaucum, Acer pictum
- Gleditschia horrida
- Gleditsia, genus
- Gleditsia japonica
- Gleditsia miosinensis
- glehnii, Picea
- Glehn's spruce
- Gleichenia, genus
- Gleichenites hakusanensis
- Gleichenites yuasensis
- Glirulus, genus
- Globicephala, genus
- Globigerina, genus
- Globigerina borealis
- Globigerina bulloides
- Globigerina cyclostoma
- Globigerina diplostoma
- Globigerina eggeri
- Globigerina incompta
- Globigerina inflata
- Globigerina nepenthes
- Globigerina pachyderma
- Globigerina quinqueloba
- Globigerinatella insueta
- Globigerinoides cyclostoma
- Globigerinoides ruber
- Globigerinoides sicana
- Globigerinoides sicanus
- Globigerinoides triloba
- Globobulimina, genus
- Globocassidulina subglobosa
- Globoquadrina altispira subsp. globosa
- Globorotalia crassaformis
- Globorotalia ikebei
- Globorotalia inflata
- Globorotalia menardii
- Globorotalia peripheroacuta
- Globorotalia peripheroronda
- Globorotalia pseudopachyderma
- Globorotalia rikuchuensis
- Globorotalia truncatulinoides
- Globorotalia tumida
- globosa, Cassidulina
- globosa, Dentoglobigerina
- globosa, Globoquadrina altispira
- globosa, Yabeina
- Globoturborotalita nepenthes
- Globularia, genus
- globularis, Rosalina
- glomerosa subsp. circularis, Praeorbulina
- glomerosa, Praeorbulina
- Glomospira pusilla
- Gloripallium crassivenium
- Gloripallium izurensis
- Glorybower
- Glossaulax, genus
- Glossaulax coticazae
- Glossaulax didyma
- Glossaulax didyma coticazae
- Glossaulax reiniana
- Glossaulax vesicalis
- glossoformis, Nilssonia
- Glycydonta itoigawae
- Glycymeris, genus
- Glycymeris albolineata
- Glycymeris altoumbonata
- Glycymeris aspersa
- Glycymeris cisshuensis
- Glycymeris convexa
- Glycymeris crassa
- Glycymeris idensis
- Glycymeris ikebei
- Glycymeris matsumoriensis
- Glycymeris matumoriensis
- Glycymeris miyagiensis
- Glycymeris munda
- Glycymeris nakamurai
- Glycymeris nakosoensis
- Glycymeris nipponica
- Glycymeirs osozawaensis
- Glycymeris pilsbryi
- Glycymeris rotunda
- Glycymeris totomiensis
- Glycymeris (Veletuceta) albolineata
- Glycymeris vestita
- Glycymeris vestitoides
- Glycymeris yamasakii
- Glycymeris yessoensis
- Glyptostrobus, genus
- Glyptostrobus europaeus
- Glyptostrobus pensilis
- Gobiidae, family
- Gobioidei, suborder
- Goby
- goisiensis, Trochus
- Gold-mouthed tun
- goliath, Acesta
- goliath, Lima
- golikovi, Macoma
- Gomphina, genus
- Gomphina neastartoides
- Gomphonema, genus
- Gomphonema acuminatum var. brebissonii
- Gomphonema intricatum
- Gomphonema olivaceum
- Gomphotherium, genus
- Gomphotherium annectens
- Gondolella, genus
- Gondolella idahoensis
- Gondolella polygnathiformis
- Goneplacidae, family
- Goniarina permiana
- Goniatid
- Goniatite
- Goniatitida, order
- Goniomya subarchiaci
- Gonostomatidae, family
- gordonis, Saccella
- Gorgansium, genus
- gotoana, Corylopsis
- gottschei, Acila
- gouldiana, Cardiomya
- gouldiana septentrionalis, Cuspidaria
- gouldi, Basterotia
- gouldi, Solen
- gouldi, Terebratalia
- gracilenta, Cuneopsis
- gracilenta, Paraclathurella
- gracilis, Epithemia sorex
- gracilis, Sorbus
- gramen, Textularia
- Gramineae, family
- gramineus subsp. heterophyllus, Ptamogeton
- gramineus, Ptamogeton
- Grammatodon, genus
- Grammatodon takiensis
- Grammoceras, genus
- Granata, genus
- Grandicrepidula grandis
- grandis, Grandicrepidula
- grandis, Solen
- granosa, Anadara
- granosa bisenensis, Anadara (Tegillarca)
- granosa, Tegillarca
- granulata, Aulacoseira
- granulata var. angustissima, Aulacoseira
- granulata var. angustissima, Melosira
- granulata, Lunella
- granulata, Melosira
- Granulated moon turban
- granuliferum, Homalopoma
- Granulifusus musasiensis
- Granuliterebra bathyrhaphe
- Grapevine
- Graptolite
- Graptolithina, subclass
- Graptopsaltria inaba
- gratiosa, Portlandia
- Gravicalymene yamakoshii
- gravitesta, Crassostrea
- gravitesta, Ostrea
- grayanus, Crenomytilus
- grayi, Coptothyris
- grayi subsp. katokiyomasai, Cervus
- Great northern tellin
- Great white shark
- Green falsejingle
- Greenland cockle
- grewingki, Arenomya
- grewingki var. elongata, Arenomya
- grewingki var. elongata, Mya
- grewingki, Mya
- Grey red-backed vole
- groenlandicus, Serripes
- Grooved crassatella
- grossa, Betula
- grosseserrata, Quercus mongolica
- Ground beetle
- Gruidae, genus
- Grus vipio
- Grylloidea, superfamily
- Gryphus insolitus