The first documented fossils to be recovered from the Bridger Formation were discovered on 11 August 1849 by Captain Howard Stansbury, who documented the discovery of fossilized shells and wood in his expedition report while scouting out the region for the United States ArmyCorps of Topographical Engineers.[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. When these claims were called into question by judge William A. Carter, Robinson brought Carter a bag filled with the fossils. One of the specimens recovered by Robinson was a well-preserved skull which resembled that of a grizzly bear. Judger Carter invited Louis Agassiz to observe the local strata, but Agassiz declined as the journey would have involved riding horseback to the site, a mode of transportation Agassiz abhorred. Carter's son-in-law, Dr. J. Van A. Carter, would go on to send a number of fossils to palaeontologist Joseph Leidy at the University of Pennsylvania in 1869. These fossils included the first Bridgerian fossil taxa, Omomys carteri; and the skull discovered by Robinson, which was described as Palaeosyops paludosus.[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.[9]
The Bridger Formation did not see a proper scientific mission until 1903, when Walter W. Granger and William Diller Matthew initiated a three-year survey of the strata, during which time Matthew identified the Bridger Formation's distinct members by using local limestone layers as marker beds. Later expeditions brought other researchers to the region, including Charles Lewis Gazin.[2]
Geology
The Bridger Formation overlies the Green River Formation and underlies the Bishop Conglomerate. 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.[11] Limestone deposits like the Sage Creek Formation separate the three distinct members which make up the Bridger Formation: Blacks Fork (Bridger B), Twin Buttes (Bridger C & D), and Turtle Bluff (Bridger E). The limestone surrounding the Bridger Formation was deposited on the beds of lakes and ponds at the site during the Eocene. William Diller Matthew used this limestone as marker beds in his initial description of the Bridger Formation in 1909.
Portions formerly considered to be part of the Bridger Formation have since been reassigned to the nearby Uinta Formation.[12]
Palaeobiology
Dozens of Early Eocene (50.3 - 46.2 Ma)[13] mammalian and invertebrate genera are known from the Bridger Formation.
Amia includes the genus jr synonyms Hypamia, Protamia, and Pappichthys.[87] The amiids A. (Pr.) gracilis and A. (Pr.) media were first listed as Bridger Formation taxa, but were listed as from the Laney Member of the Green river Formation by Grande and Bemis (1998). The species A. (Pa.) cornsonii, A. depressus, A. (H.) elegans, and A. newberrianus are either Bridger formation or Green River Formation per Grande and Bemis.[87]
^Nace, R.L. (1939). "Geology of the northwest part of the Red Desert, Sweetwater and Fremont Counties, Wyoming". Wyoming Geological Survey Bulletin (27). Laramie, Wyoming: Wyoming Geological Survey: 51.
^Spamer, Earle E.; Daeschler, Edward; Vostreys-Shapiro, L. Gay (1995). "A Study of Fossil Vertebrate Types in The Academy of Natural Sciences of Philadelphia". Scientific Publications. 16. Academy of Natural Sciences of Philadelphia: 25.
^Osborn, H. F.; Scott, W.B.; Speir, Jr., F. (1878). "Paleontological Report of the Princeton Scientific Expedition of 1877". Contributions from the Museum of Geology and Archaeology, Princeton College. Princeton College.
^Smith, M. E., Singer, B., & Carroll, A. (2003). 40Ar/39Ar geochronology of the Eocene Green River Formation, Wyoming. Geological Society of America Bulletin, 115(5), 549-565.
^Cashion, W.B.; Donnell, J.R. (1974). "Revision of nomenclature of the upper part of the Green River Formation, Piceance Creek basin, Colorado, and eastern Uinta basin, Utah". Contributions to Stratigraphy: U.S. Geological Survey Bulletin (1394). U.S. Geological Survey Bulletin: G1 - G9.
^McGrew, P. O.; Berman, J. E.; Hummel, J. M.; Simpson, G. G.; Wood, A. E. (1959). "The geology and paleontology of the Elk Mountain and Tabernacle Butte area, Wyoming". Bulletin of the American Museum of Natural History. 3 (117). American Museum of Natural History: 117–176.
^ abHay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 654.
^Hay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 650–654.
^ abHay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 787.
^Hay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 649–650.
^Hay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 792.
^ abcdefgMatthew, W. D. (1909). "The Carnivora and Insectivora of the Bridger Basin, middle Eocene". Memoirs of the American Museum of Natural History. 9. American Museum of Natural History: 289–567.
^Hay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 761.
^Hay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 760–761.
^ abHay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 759–760.
^Hay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 755.
^ abcdeMarsh, O. C. (1872). "Preliminary description of new Tertiary mammals. Part I.". American Journal of Science. 4 (20): 122–128.
^Miyata, K. (2007). "New species of Trogosus (Tillodontia, Mammalia) from the Green River Basin, Wyoming". Journal of Vertebrate Paleontology. 27 (3). Taylor & Francis: 661–675. doi:10.1671/0272-4634(2007)27[661:nsottm]2.0.co;2.
^Marsh, O. C. (1875). "Notice of new Tertiary mammals, IV". American Journal of Science. 9 (51): 239–250.
^Spamer, Earle E.; Daeschler, Edward; Vostreys-Shapiro, L. Gay (1995). "A Study of Fossil Vertebrate Types in The Academy of Natural Sciences of Philadelphia". Scientific Publications. 16. Academy of Natural Sciences of Philadelphia: 259.
^Matthew, W. D. (1909). "The Carnivora and Insectivora of the Bridger Basin, middle Eocene". Memoirs of the American Museum of Natural History. 9. American Museum of Natural History: 523–534.
^ abcHay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 740.
^Marsh, O. C. (1882). "Preliminary description of new Tertiary mammals. Part II". American Journal of Science. 4 (21): 202–224.
^Morlo, M.; Gunnell, G. F. (2003). "Small Limnocyonines (Hyaenodontidae, Mammalia) from the Bridgerian Middle Eocene of Wyoming: Thinocyon, Prolimnocyon, and Iridodon, new genus". Contributions from the Museum of Paleontology, University of Michigan. 31 (2). University of Michigan: 43–78.
^Morlo, M.; Gunnell, G. F. (2005). "New species of Limnocyon (Mammalia, Creodonta) from the Bridgerian (middle Eocene)". Journal of Vertebrate Paleontology. 25 (1). Taylor & Francis: 251–255. doi:10.1671/0272-4634(2005)025[0251:nsolmc]2.0.co;2.
^ abMatthew, W. D.; Granger, W. (1915). "A revision of the Lower Eocene Wasatch and Wind River faunas". Bulletin of the American Museum of Natural History. 34 (1). American Museum of Natural History: 1–103.
^Hay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 758.
^ abCope, E. D. (1872). "Descriptions of some new Vertebrata from the Bridger Group of the Eocene". Proceedings of the American Philosophical Society. 12. American Philosophical Society: 460–465.
^ abMarsh, O. C. (1872). "Preliminary description of new Tertiary mammals. Part II". American Journal of Science. 4 (21): 202–224.
^Cope, E. D. (1872). "Third account of new Vertebrata from the Bridger Eocene of Wyoming Territory". Proceedings of the American Philosophical Society. 12. American Philosophical Society: 469–472.
^Wortman, J. L. (1902). "Studies of Eocene Mammalia in the Marsh Collection, Peabody Museum". The American Journal of Science. 14 (79). American Journal of Science: 17–23. doi:10.2475/ajs.s4-14.79.17. hdl:2027/uc1.c034644444.
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^ abSimpson, G. G. (1959). "Two new records from the Bridger Middle Eocene of Tabernacle Butte, Wyoming". American Museum Novitates. American Museum of Natural History: 1–5.
^ abWheeler, W. H. (1961). "Revision of the Uintatheres". Peabody Museum of Natural History Bulletin (14). Peabody Museum of Natural History: 1–93.
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^ abHay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 742.
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^Matthew, W. D. (1909). "The Carnivora and Insectivora of the Bridger Basin, middle Eocene". Memoirs of the American Museum of Natural History. 9 (6). American Museum of Natural History: 497–498.
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^ abCope, E. D. (1872). "Notices of New Vertebrata from the Upper Waters of Bitter Creek, Wyoming Territory". Proceedings of the American Philosophical Society. 12 (86). American Philosophical Society: ?.
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^ abOsborn, H. F. (1908). "New or little known titanotheres from the Eocene and Oligocene". Bulletin of the American Museum of Natural History. 24 (32). American Museum of Natural History: 599–617.
^Gunnel, G. F.; Yarborough, V. L. (2000). "Brontotheriidae (Perissodactyla) from the late early and middle Eocene (Brigerian), Wasatch and Bridger formations, southern Green River Basin, southwestern Wyoming". Journal of Vertebrate Paleontology. 20 (2). Taylor & Francis: 349–368. doi:10.1671/0272-4634(2000)020[0349:bpftle]2.0.co;2.
^Stucky, R. K. (1984). "The Wasatchian-Bridgerian land Mammal Age boundary (early to middle Eocene) in western North America". Annals of Carnegie Museum. 52 (12). Carnegie Museum: 347–382.
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^ abGingerich, P. D. (1979). "Phylogeny of middle Eocene Adapidae (Mammalia, Primates) in North America: Smilodectes and Notharctus". Journal of Paleontology. 53 (1). Paleontological Society: 153–163.
^ abHay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 787–788.
^ abHay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 450.
^ abMuldoon, K. M.; Gunnell, G. F. (2002). "Omomyid primates (Tarsiiformes) from the Early Middle Eocene at South Pass, Greater Green River Basin, Wyoming". Journal of Human Evolution. 43 (4). Elsevier: 479–511. doi:10.1006/jhev.2002.0591. PMID12393005.
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^Murphey, P. C.; Dunn, R. H. (2009). "Hemiacodon engardae, a new species of omomyid primate from the earliest Uintan Turtle Bluff member of the Bridger Formation, southwestern Wyoming, USA". Journal of Human Evolution. 57 (2). Elsevier: 123–130. doi:10.1016/j.jhevol.2009.05.006. PMID19625072.
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^ abcdKrishtalka, L.; Stucky, R. K. (1983). "Revision of the Wind River faunas, early Eocene of central Wyoming. Part 3. Marsupialia". Annals of Carnegie Museum. 52 (9). Carnegie Museum: 205–227.
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^Woodward, Arthur Smith (1895). "Catalogue of the Fossil Fishes in the British Museum (Natural History)". Catalogue of the Fossil Fishes. 3. Taylor and Francis: 373.
^Spamer, Earle E.; Daeschler, Edward; Vostreys-Shapiro, L. Gay (1995). "A Study of Fossil Vertebrate Types in The Academy of Natural Sciences of Philadelphia". Scientific Publications. 16. Academy of Natural Sciences of Philadelphia: 103, 105, 386–387.
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^ abLeidy, J. (1870). "Descriptions of Emys jaenesi, E. haydeni, Baena arenosa, and Saniwa ensidens". Proceedings of the American Philosophical Society. American Philosophical Society: 123–124.
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^Leidy, J. (1870). "Remarks on Poikilopleuron valens, Clidastes intermedius, Macrosaurus proriger, Baptemus wyomingensis, and Emys stevensonianus". Proceedings of the Academy of Natural Sciences of Philadelphia. 22 (1). Academy of Natural Sciences of Philadelphia: 3–5.
^Spamer, Earle E.; Daeschler, Edward; Vostreys-Shapiro, L. Gay (1995). "A Study of Fossil Vertebrate Types in The Academy of Natural Sciences of Philadelphia". Proceedings of the American Philosophical Society. 16. The Academy of Natural Sciences of Philadelphia: 158.
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^Hay, Oliver Perry (1902). "Bibliography and Catalogue of the Fossil Vertebrata of North America". Bulletin of the United States Geological Survey. 179. U.S. Government Printing Office: 454.
^Hay, O. P. (1907). "Descriptions of seven new species of turtles from the Tertiary of the United States". Bulletin of the American Museum of Natural History. 23 (34). American Museum of Natural History: 847–863.
^Lucas, Spencer G.; Zidek, Jiri (1993). "Vertebrate Paleontology in New Mexico". Vertebrate Paleontology in New Mexico. 2. New Mexico Museum of Natural History and Science: 260.
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^Gilmore, C. W. (1928). "Fossil Lizards of North America". Memoirs of the National Academy of Sciences. 22 (3). National Academy of Sciences: 34.