Before colonization, the lands making up the Bridger Formation had been inhabited by the Apsáalooke, Bannock, Eastern Shoshone, Hinono'eino, Očhéthi Šakówiŋ, Só'taeo'o, Tsétsêhéstâhese, and Ute nations.

[4] European settlers began to settle the area around the Bridger Formation in the 19th century, beginning with the establishment of the Oregon Trail in 1830.

[7] In the early-1860s, trapper Jack Robinson claimed to have discovered a number of sites along the base of the Uinta Mountains where grizzly bears had been turned to stone.

[8] Another researcher responsible for sending off specimens was Dr. Joseph K. Corson, a close friend of Leidy's who hosted him and his family on two three to Fort Bridger in 1872, 1873, and 1879.

The famously fossiliferous Bridger Formation attracted a number of famed palaeontologists including Henry Fairfield Osborn, William Berryman Scott, and F. Speir, Jr.[10] The Bridger Formation also became a battleground in the Bone Wars between Edward Drinker Cope and Othniel Charles Marsh.

The boundary with the former occurs in the mid-Eocene after the region completed a transition to a drier environment from a moist climate in the early Eocene.

Achaenodon[14] A. insolens A. robustus Helohyus[15] H. lentus H. milleri H. plicodon Parahyus[14] P. vagus Antiacodon[16] A. pygmaeus A. venustus Homacodon[17] H. vagans Microsus[18] M. cuspidatus Oodectes[19] O. herpestoides Harpalodon[21] H. sylvestris Miacis[22] M. bathygnathus M. edax M. parvivorus M. vorax M. vulpinus Miocyon[19] M. major Uintacyon[23] U. jugulans Vulpavus[23] V. ovatus V. profectus Viverravus[24] V. nitidus Palaearctonyx[19] P. meadi Apatemys[25] A. bellus A. bellulus Megalesthonyx[26] M. hopsoni Tillodon[27] T. fodiens Trogosus[28] T. castoridens T. gazini T. hyracoides T. latidens T. vetulus Pantolestes[29][30] P. elegans P. intermedius P. longieundus P. natans P. phocipes Didelphodus[31] D. altidens Entemodon[30] E. comptus Iridodon[32] I. datzae Limnocyon[33] L. cuspidens L. medius L. velox L. verus Prolimnocyon[34] P. antiquus Proviverra[35] P. americana Sinopa[36][37][16][38][39] S. aculeatus S. agilis S. eximia S. grangeri S. insectivorus S. major S. minor S. pungens S. rapax Tritemnodon[19] T. hians T. strenuus Aelurotherium[40] A. bicuspis A. latidens Machaeroides[19] M. eothen M. simpsoni Patriofelis[41] P. ferox P. ulta Bathyopsis[42] B. fissidens Eobasileus[43] E. cornutus Uintatherium[44] U. anceps Talpavus[45] T. nitidus Centetodon[30] C. bacchanalis C. bembicophagus C. pulcher Marsholestes[19] M. dasypelix Nyctilestes[46] N. serotinus Nyctitherium[46] N. gunnelli N. priscus N. serotinum N. velox Hypictops[47] H. syntaphus Palaeictops[41] P. bridgeri Scenopagus[48] S. curtidens S. edenensis S. priscus Harpagolestes[49] H. immanis H. macrocephalus Mesonyx[50] M. lanius M. obtusidens Synoplotherium[51] S. canius Orthocynodon[52] O. antiquus Eotitanops[53] E. borealis Palaeosyops[54][55][2][53] P. fontinalis P. paludosus P. robustus P. ultimus Telmatherium[25][56] T. validum T. validus Mesatirhinus[42] M. megarhinus Oligotomus[57] O. cinctus Orohippus[58] O. agilis O. ballardi O. major O. osbornianus O. procyoninus O. progressus O. pumilus O. sylvaticus O. uintanus Hyopsodus[59] H. minusculus H. lepidus H. paulus H. pygmaeus H. tonski Hyrachyus[60] H. eximius H. minor H. paradoxus Triplopus[61] T. cubitalis T. obliquidens Isectolophus[62][63] I. latidens I. radinskyi Helaletes[64] H. nanus Brachianodon[65] B. westorum Metacheiromys[66] M. marshi Tetrapassalus[67] T. proius Alveojunctus[68] A. minutus Microsyops[34][37][69] M. angustidens M. annectens M. elegans M. knightensis M. scottianus Uintasorex[citation needed] U. parvulus Notharctus[70][71] N. robinsoni N. robustior N. tenebrosus N. venticolus Smilodectes[70] S. gracilis Anaptomorphus[72][73] A. aemulus A. westi Gazinius[74] G. amplus G. bowni Hemiacodon[75][76] H. engardae H. gracilis Omomys[71] O. carteri Trogolemur[19] T. myodes Washakius[73] W. insignis Mysops[77] M. fraternus M. minimus M. parvus Acritoparamys[78] A. wyomingensis Leptotomus[78] L. parvus Mytonomys[79] M. coloradensis Paramys[80] P. delicatior P. delicatus Pseudotomus[81][82] P. hians P. horribilis P. robustus Quadratomus[79] Q. grandis Thisbemys[78][79] T. corrugatus T. perditus Franimys[80] F. buccatus Reithroparamys[80][79] R. delicatissimus R. huerfanensis Knightomys[79] K. cuspidatus K. depressus K. huerfanensis K. senior Taxymys[25] T. lucaris Tillomys[25] T. parvidens T. senex Herpetotherium[83] H. innominatum H. knighti Peratherium[83] P. comstocki P. marsupium Armintodelphys[83] A. blacki Peradectes[83] P. chesteri Aletornis[84] A. bellus A. gracilis A. nobilis A. pernix A. venustus Minerva[85][86] M. leptosteus M. saurodosis Amia includes the genus jr synonyms Hypamia, Protamia, and Pappichthys.

(Pa.) sclerops "bluffs of Cottonwood Creek", Wyoming Nomen dubium per Grande & Bemis (1998) as Amiinae indeterminate[87] A.

uintaensis Nomen dubium per Grande & Bemis (1998) as Amiinae indeterminate[87] Rhineastes[51] R. peltatus R. smithii Lepisosteus[93][94] L. atrox L. simplex Phareodus[95] P. encaustus P. testis Crocodilus[96] C. elliottii C. grypus C. parvus C. sulciferus Glyptosaurus[99] G. sphenodon G. sylvestris Paraglyptosaurus[100] P. princeps Xestops[101] X. vagans Boavus B. brevis B. occidentalis Lithophis L. sargenti Protagras P. lacustris Tinosaurus[103] T. pristinus T. stenodon Lestophis[104] L. anceps L. crassus Spathorhynchus[105] S. fossorium Iguanavus[106] I. exilis Saniwa[107] S. ensidens S. major Baena[108] B. arenosa Chisternon[109] C. hebraicum C. undatum Anosteira[110] A. ornata A. radulina Baptemys[111] B. wyomingensis Emys[107][25][112][113] E. jaensi E. latilabiatus E. stevensonianus E. wyomingensis Hybemys[114] H. arenarius Echmatemys[115] E. haydeni E. septaria E. wyomingensis Hadrianus[72][116] H. allabiatus H. corsoni H. octonaria H. quadratus Apalone[117] A. extensa A. heteroglypta A. postera A. trionychoides Axestemys[118] A. byssina A. cerevisia A. salebrosa A. uintaensis Hummelichelys[119] H. annae H. ellipticus H. grangeri H. guttatus Plastomenus[36] P. molopinus P. oedemius P. tantillus P. thomasi P. visendus Platypeltis[120][121] P. serialis P. trepida Trionyx[122] T. concentricus Naocephalus[123] N. porrectus