- Tabanidae, family
- tabatai, Paleoparadoxia
- tabernaemontani, Schoenoplectus
- tabernaemontani, Scirpus
- Tabulata, order
- Tabulate coral
- Tachypleus, genus
- Taeniopteris lanceolata
- Taeniopteris latecostata
- Taeniopteris nystroemii
- Taeniopteris schenkii
- Taeniopteris setamaiensis
- Taeniopteris tingii
- Taipiridae, family
- Taisyakuphyllum, genus
- Taiwan beech
- Taiwan fir
- Taiwania, genus
- Taiwania japonica
- tajimae, Limopsis
- takeharai, Malletia
- takahashii, Fortipecten
- takahashii, Paracalamites
- takaianus, Equisetites
- takaii, Apolymetis
- takaii, Leporimetis
- takashimensis, Pitar
- takedai, Cyclocardia
- takeokensis, Clathrodrillia
- takeokensis, Crassispira
- takeyamai, Cycladicama
- takiensis, Grammatodon
- talonata, Talonostrea
- Talonostrea talonata
- Talpidae, family
- tamalis, Discoaster
- Tambatitanis amicitiae
- tamon, Hyperpuzosia
- tanabensis, Cyphastrea
- tanabensis, Cyphastrea chalcidicum
- tanaguraensis, Turritella
- tanaii, Buccella
- Tanakia lanceolata
- tanassevitschi, Chlamys
- tanassevitschi, Leochlamys
- tanegashimensis, Ocadia
- Tangshanella, genus
- Tangshanella nakakuboensis
- tani, Cyclammina
- Taniwhasaurus mikasaensis
- Tapes, genus
- Tapes japonica
- Tapes microsiratori
- Tapes nagahamaensis
- Tapes philippinarum
- Tapes platyptycha
- Tapes platyptychus
- Tapes sericeus
- Tapes (Siratoria) microsiratori
- Tapir
- Taras ferruginata
- Tateiwaia, genus
- Tateiwaia tateiwai
- Tateiwaia yamanarii
- tateiwai, Chione
- tateiwai, Leukoma
- tateiwai, Propeamussium
- tateiwai, Protothaca
- tateiwai, Tateiwaia
- tatewakii, Rhododendron
- tatunokutiensis, Anadara
- taukushi, Cimbex connatus
- taurus, Carcharias
- taurus, Odontaspis
- tauyensis, Pseudamiantis
- Taxaceoxylon, genus
- Taxodiaceae, subfamily
- Taxodioxylon, genus
- Taxodioxylon sequoianum
- Taxodium, genus
- Taxodium distichum
- Taxodium dubium
- Taxus, genus
- Taxus cuspidata
- Tectonatica, genus
- Tectonatica janthostomoides
- Tectonatica russa
- Tectus fenestratus
- Tectus japonicus
- Tectus (Rochia) japonicus
- Tectus yamadensis
- Tedorosaurus aswaensis
- Tegillarca, genus
- Tegillarca addita
- Tegillarca granosa
- Tegula (Chlorostoma) hiranitensis
- Tegula (Chlorostoma) microstriata
- Tegula hiranitensis
- Tegula microstriata
- Tegula pfeifferi
- Telescopium, genus
- Tellina, genus
- Tellina notoensis
- Tellina vancouverensis
- Tellinella crucigera
- Tellinides, genus
- Tellinimactra edentula
- Telmessus, genus
- Temnopleurus, genus
- Temnopleurus toreumaticus
- Temple juniper
- Tempskya, genus
- Tenagodus, genus
- tenebrica, Didimacar
- Tenebrionidae, family
- ten, Martes
- Tenthredinoidea, superfamily
- tenue, Archaeospongoprunum
- tenuifolium, Acer
- tenuifolium, Cinnamomum
- tenuiliratum, Gaudryceras
- tenuiliratum, Neogaudryceras
- tenuiliratus, Crassatella
- tenuiliratus, Crassatellites
- tenuis, Ennucula
- tenuis, Mitrella
- tenuis, Mohnia yanamii
- tenuis, Retifusus virens
- tenuis, Scaphechinus
- tenuis, Terebratalia
- Terebellidae, family
- Terebra, genus
- Terebra japonica
- Terebra osawanoensis
- Terebra quoygaimardi
- Terebra (Strioterebrum), genus
- Terebratalia coreanica
- Terebratalia gouldi
- Terebratalia radiata
- Terebratalia tenuis
- Terebratulina, genus
- Terebratulina chichibuensis
- Terebratulina crossei
- Terebratulina honsyuensis
- Terebratulina japonica
- Terebratulina kiiensis
- Terebratulina peculiaris
- Terebratulina simosensis
- Teredo, genus
- Teredolie
- Termitidae, family
- Ternstroemia maekawai
- Terpnosia nigricosta
- Terpnosia vacua
- Terpsinoë, genus
- tertioseptata, Yokoyamaella
- teshimaense, Vasticardium
- Testudines, order
- Testudinidae, family
- Tetoria endoi
- Tetoria sanchuensis
- Tetoria yokoyamai
- tetoriensis, Corbicula
- tetoriensis, Fukuisaurus
- tetoriensis, Myrene
- Tetorimya carinata
- Tetracorallia
- Tetracyclus emarginatus
- tetragona, Williriedellum
- Tetraodontidae, family
- tetrapera, Cyrtocapsella
- Texanites kawasakii
- Texanites (Plesiotexanites) kawasakii
- Textularia gramen
- Thais, genus
- Thais bronni
- Thais (Reishia) bronni
- Thalassinoides, ichnogenus
- Thalassionema, genus
- Thalassiosira, genus
- Thalassiosira antiqua
- Thalassiosira manifesta
- Thalassiosira oestrupii
- Thalassiosira yabei
- Thamnasteria, genus
- Thamnopora, genus
- Thaumatopteris, genus
- Thaumatopteris elongata
- Theora, genus
- Theora fragilis
- Theora lata
- Theora lubrica
- Theropod
- Theropoda, suborder
- Therizinosaurus, genus
- Thestyleda yokoyamai
- Thetis, genus
- thibetanus, Selenarctos
- thibetanus, Ursus
- Tholitoma nishimotoi
- Tholospyris, genus
- thomasiana, Rapana
- Thomisidae, family
- thonii var. minor, Parasphenophyllum
- Thorn coral
- Thracia, genus
- Thracia asahiensis
- Thracia chigayensis
- thraciaeformis, Megayoldia
- thraciaeformis, Portlandia
- thraciaeformis, Yoldia
- Thracia genbiana
- Thracia kakumana
- Threaded fig shell
- Thuja standishii
- Thujopsis dolabrata
- thumensis, Cocconeis
- thunbergii, Corylus heterophylla
- thunbergii, Persicaria
- thunbergii, Pinus
- thunbergii, Polygonum
- Thyasira, genus
- Thyasira bisecta
- Thyasira bisecta var. nipponica
- Thyasira (Conchocele) bisecta
- Thyasira tokunagai
- Thyasiridae, family
- Thylacodes, genus
- Thylacodes adamsii
- Tiborella florida
- Tick
- tiganouranus, Chicoreus
- tiganouranus, Rhizophorimurex
- Tiger
- tigris, Panthera
- Tilia, genus
- tiliaefolia, Ficus
- Tilia hommashinichii
- Tilia japonica
- Tilia kabutoiwaensis
- Tilia maximoviczianoides
- Tilia miqueliana
- Tilia protojaponica
- Tilia sekiensis
- Timoclea itoigawae
- Timoclea micra
- Timoclea minuta
- tinctoria var. microphylla, Alnus
- tingii, Taeniopteris
- tintinnabulum rosa, Balanus
- Tipheophyllum dilatoseptatum
- Tipula (Acutipula), subgenus
- titaensis, Callianassa
- titaensis, Callianopsis
- Titanosaurus, genus
- Toad
- tobijei, Myliobatis
- tochigiensis, Cyclopecten
- tochigiensis, Microstomus
- tochiyensis, Turbo
- Todites, genus
- togariensis, Ancistrolepis
- tokaiensis, Limopsis
- tokiensis, Proclava
- tokiensis, Rhinoclavis
- tokunagai, Acharax
- tokunagai, Acilana
- tokunagai, Cerithidea
- tokunagai, Conus
- tokunagai, Cyclocardia
- tokunagai, Dicrocerus
- tokunagai, Hataiyoldia
- tokunagai var. hayasakai, Acilana
- tokunagai var. hayasakai, Hataiyoldia
- tokunagai var. hayasakai, Megayoldia
- tokunagai var. hayasakai, Portlandia
- tokunagai, Linthia
- tokunagai, Megayoldia
- tokunagai, Patinopecten
- tokunagai, Portlandia
- tokunagai, Solemya
- tokunagai, Thyasira
- tokunagai, Turritella
- tokunagai, Venericardia
- tokunagai, Volvulella
- tokunagai, Yabepecten
- tokunagai, Yoldia
- tokyoensis hokurikuensis, Mizuhopecten
- tokyoensis hokurikuensis, Patinopecten
- tokyoensis, Macoma
- tokyoensis, Mizuhopecten
- tokyoensis, Patinopecten
- tokyoensis sematensis, Mizuhopecten
- tokyoensis sematensis, Patinopecten
- Tomistoma schlegelii
- tomitensis, Lucinoma
- toneana, Carditellopsis
- Tonna, genus
- Tonna luteostoma
- Toothed whale
- Top-snail
- torano, Picea
- Torch
- toreumaticus, Temnopleurus
- Toringo crabapple
- toringo, Malus
- torinosuensis, Opis
- toriyamai, Aokiichthys
- toriyamai, Cardinia
- toriyamai, Lonsdaleoides
- Torreya, genus
- Torreya yoshiokaensis
- Tortoise
- tosaensis, Placocoenia
- Tosapecten, genus
- Tosapecten nabaensis
- Tosapecten suzukii var. fujimotoi
- Tosapecten suzukii var. inflatus
- Tosapecten suzukii subsp. suzukii
- Tosastroma, genus
- toshioi, Batillaria
- totomiensis, Glycymeris
- totomiensis, Macoma
- tottoriense, Acer
- Toxicodendron orientale
- Toxicodendron trichocarpum
- toyamaensis, Cardilia
- toyamaensis, Megayoldia
- toyamaensis, Portlandia
- Toyamasauripus masuiae
- Toyotamaphimeia machikanensis
- Trachodon, genus
- Trachycarcinus huziokai
- Trachycardium angustum
- Trachycardium multispinosum
- Trachycarpus, genus
- Trachydomia conica
- Trachydomia magna
- Trachydomia nodosa
- Trachyspira conica
- Trachyspira magna
- Transennatia, genus
- transformis, Anisomyon
- transitoria, Praeorbulina
- transversale, Flabellum
- Trapa, genus
- Trapa bispinosa var. makinoi
- Trapa discoidpoda
- Trapa incisa
- Trapa japonica
- Trapa japonica var. tuberculifera
- Trapa macropoda
- Trapa mammillifera
- Trapa manshurica
- Trapa maximowiczii
- Trapa natans
- Trapa natans var. pumila
- Trapa octotuberculata
- Trapa platycerata
- Trapella sinensis
- trapelloides, Nymphaeites
- Trapezium, genus
- Trapezium horse conch
- Trapezium liratum
- Trapezium modiolaeforme
- trapezium, Pleuroploca
- trapezoidalis, Permoperna
- tremula var. sieboldii, Populus
- Tresus, genus
- Tresus keenae
- Triactoma, genus
- Triadica, genus
- Triadica sebifera
- Triadica sebifera var. pleistoceaca
- triadicus, Procyclolites
- Triadomegalodon, genus
- triandra, Salix
- triangularis, Cruciloculina
- triangulatus, Schoenoplectus
- triangulatus, Scirpus
- Triassoblatta okafujii
- Triassocampe, genus
- Triassocampe coronata
- Triassocampe deweveri
- Tribolodon, genus
- Tribolodon hakonensis
- tricarinata, Triloculina
- Triceratium, genus
- Triceratium annulatum
- Triceratium favus f. quadrata
- Triceratium favus var. quadrata
- trichocarpum, Toxicodendron
- Trichocera, genus
- Trichopeltarion huziokai
- Trichoptera, order
- Trichotropis bicarinata
- Trichotropis unicarinata
- Tricolocapsa, genus
- tricuspidata, Cudrania
- tricuspidata, Maclura
- tricuspidata, Parthenocissus
- tricuspis, Boehmeria
- Tridacophyllia lactuca japonica
- tridentata, Biddulphia tridentata
- tridentata, Biddulphia tuomeyi
- tridentata, Cavolinia
- tridentata f. tridentata, Biddulphia
- Tridonta, genus
- Tridonta alaskensis
- Tridonta borealis
- Tridonta filatovae
- Trifarina kokozuraensis
- trifolia, Pinus
- trifoliata, Menyanthes
- trigona, Bakevellia
- trigona, Chione
- trigona, Chione (Gnidiella)
- trigona, Chionopsis
- trigona, Neobakevellia
- Trigonarca, genus
- Trigonia, genus
- Trigonia hokkaidoana
- Trigonia senex
- Trigonia sumiyagura
- Trigonioides, genus
- Trigonioides (Kumamotoa) mifunensis
- Trigonioides mifunensis
- trigonula, Triloculina
- Trilobita, class
- Trilobite
- triloba, Globigerinoides
- Triloculina tricarinata
- Triloculina trigonula
- trinervis, Smilax
- Trionychidae, family
- Trionyx, genus
- Trionyx kazusensis
- Trionyx miensis
- Trionyx ubeensis
- Triplostephanus fenestratus
- tripteron, Polystichum
- Tripterygium, genus
- triqueter, Schoenoplectus
- Trisidos, genus
- Trisidos kiyonoi
- trispinosa, Diacria
- Tristichotrochus consors
- Tristichotrochus haliarchus
- Tritia japonica
- Triticites, genus
- Triticites katoi
- Triticites simplex
- Tritonalia adunca
- Triton oregonensis
- Triton (Priene) oregonensis
- Triton's trumpet
- trituberculoides, Galeodea
- Tritylodontid
- Tritylodontidae‰È
- Trizygia oblongifolia
- Trochidae, family
- Trochocerithium shikoensis
- Trochocerithium shikokuensis
- Trochodendron aralioides
- Trochodendron aralioides var. longifolium
- trochulus, Siphonalia
- Trochus goisiensis
- Trochus (Infundibulum) goisiensis
- Trophon (Boreotrophon) candelabrum
- Trophon candelabrum
- Trophon kagaensis
- Trophonopsis candelabrum
- Trophonopsis kagaensis
- Tropidelasma yamasugensis
- troscheli, Dosinia
- troscheli, Dosinorbis
- troscheli, Phacosoma
- True conch
- True limpet
- truncata, Dumasia
- truncata, Parafusulina
- truncatulinoides, Globorotalia
- Tryblionella punctata
- tryblium, Mizuhopecten
- tryblium, Patinopecten
- Tryplasma, genus
- tschonoskii, Carpinus
- tschonoskii, Ligustrum
- tsuboiana, Noditerebra
- tsuboiana, Pristiterebra
- tsudae, Alnus
- tsudai, Eostegodon
- tsudai, Stegolophodon
- Tsuga, genus
- Tsuga aburaensis
- Tsuga diversifolia
- Tsuga miocenica
- Tsuga sieboldii
- tsukiyoshiensis, Minolia
- tsurumaru, Borniopsis
- tuberculata, Haliotis tuberculata
- tuberculata subsp. tuberculata, Haliotis
- tuberculatus, Conus
- tuberculifera, Trapa japonica
- tuberculosus, Parviconus
- tuberculosus, Profundiconus
- tuberosus, Fusinus
- tubura, Calyptraea
- Tucetonella munda
- Tugali decussatoides
- tugaruana, Cryptonatica
- tugaruana, Natica clausa
- Tugurium, genus
- Tugurium makiyamai
- Tuliptree
- Tulotomoides, genus
- Tulotomoides japonicus
- Tulotomoides sanaguensis
- tumida, Caulastraea
- tumida, Globorotalia
- Tumidimytilus tichanovitchi
- tuomeyi var. tridentata, Biddulphia
- Tupelo
- Turbinaria brueggemanni
- turbinata, Aesculus
- Turbo, genus
- Turbo correensis
- Turbo guttata
- Turbo (Marmorostoma) tochiyensis
- Turbo megamiensis
- Turbo minoensis
- Turbonilla, genus
- Turbonilla candida
- Turbonilla paucicostulata
- Turbo ozawai
- Turborotalita quinqueloba
- Turbo tochiyensis
- Turcica, genus
- turgida, Epithemia
- turgida, Navicula
- Turnip-shaped rapana
- Turridae, family
- Turrilites costatus
- Turris, genus
- Turritella, genus
- Turritella andenensis
- Turritella chichibuensis
- Turritella chichibuensis elegantula
- Turritella cingulifera
- Turritella fortilirata
- Turritella (Hataiella) elegantula
- Turritella (Haustator) andenensis
- Turritella (Haustator) nipponica
- Turritella ikebei
- Turritella infralirata
- Turritella kadonosawaensis
- Turritella karatsuensis
- Turritella kurosio
- Turritella (Neohaustator) nipponica
- Turritella (Neohaustator) saishuensis
- Turritella nipponica
- Turritella nipponica nojimaensis
- Turritella nipponica nomurai
- Turritella nomurai
- Turritella oyasio
- Turritella perterebra
- Turritella poronaica
- Turritella sagai
- Turritella saishuensis
- Turritella saishuensis etigoensis
- Turritella saishuensis motidukii
- Turritella shataii
- Turritella s-hataii
- Turritella tanaguraensis
- Turritella tokunagai
- Turritella yoshidai
- Turtle
- turunagai, Pholadomya
- tuscula, Navicula