Bridger Formation

The Bridger Formation is a geologic formation in southwestern Wyoming. It preserves fossils dating back to the Bridgerian and Uintan stages of the Paleogene Period.^[2] The formation was named by American geologist Ferdinand Vandeveer Hayden for Fort Bridger, which had itself been named for mountain man Jim Bridger.^[3] The Bridger Wilderness covers much of the Bridger Formation's area.

Bridger Formation
Stratigraphic range: Bridgerian - Uintan
Grizzly Buttes, a major feature of the Bridger Formation
Type	Formation
Underlies	Bishop Conglomerate
Overlies	Green River Formation
Thickness	215 feet (66 m) - 270 feet (82 m)[1]
Location
Region	Wyoming
Country	United States
Type section
Named for	Bridger Wilderness
Named by	F.V. Hayden

History

Jim Bridger

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. Fort Bridger – for which the formation would later be named – was established in 1843 by Jim Bridger and Louis Vasquez. In 1868, the remaining Indigenous communities in the area were displaced by the Treaty of Fort Bridger, removing them to the Fort Hall Indian Reservation and Wind River Indian Reservation.^[5][6]

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 Army Corps 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 was described and named in 1869 by H.V. Hayden while conducting a geological survey in the region on behalf of the United States Geological and Geographical Survey of the Territories. 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 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.

Eutherians

Artiodactyls

Achaenodontidae

Genus	Species	Location	Stratigraphic position	Material	Images
Achaenodon[14]	A. insolens	Wyoming		AMNH 5143, fragmentary mandible
	A. robustus	Wyoming		PU 10033, partial skull and mandible
Helohyus[15]	H. lentus	Sweetwater County, Wyoming
	H. milleri	Sweetwater County, Wyoming	Bridger B & C
	H. plicodon	southwestern Wyoming	Bridger B & C
Parahyus[14]	P. vagus	Wyoming		YPM 10972, partial mandible

Homacodontidae

Genus	Species	Location	Stratigraphic position	Material	Images
Antiacodon[16]	A. pygmaeus	southwestern Wyoming	Bridger C & D
	A. venustus	Sweetwater County, Wyoming	Bridger D	YPM 11765, a tooth
Homacodon[17]	H. vagans	southwestern Wyoming	Bridger C & D	YPM 13129, skull and jaws
Microsus[18]	M. cuspidatus	southwestern Wyoming	Bridger B - D

Carnivoramorphans

stem Carnivoramophans

Genus	Species	Location	Stratigraphic position	Material	Images
Oodectes[19]	O. herpestoides	Uinta County, Wyoming		AMNH 140008, nearly-complete skull[20]

Miacidae

Genus	Species	Location	Stratigraphic position	Material	Images
Harpalodon[21]	H. sylvestris	Washakie County, Wyoming
Miacis[22]	M. bathygnathus	Henry's Fork Hill, Sweetwater County, Wyoming	Bridger C
	M. edax	Wyoming
	M. parvivorus	Lincoln and Uinta Counties, Wyoming	Bridger B & C
	M. vorax	Wyoming
	M. vulpinus	Wyoming
Miocyon[19]	M. major	Blue Point Marker, Park County, Wyoming
Uintacyon[23]	U. jugulans	Henry's Fork Hill, Sweetwater County, Wyoming	Bridger C
Vulpavus[23]	V. ovatus	Little Dry Creek, Uinta County, Wyoming
	V. profectus	Uinta County, Wyoming

Viverravidae

Genus	Species	Location	Stratigraphic position	Material	Images
Viverravus[24]	V. nitidus	Wyoming

Carnivorans

Genus	Species	Location	Stratigraphic position	Material	Images
Palaearctonyx[19]	P. meadi	Twin Buttes, Sweetwater Counties, Wyoming

Cimolestans

Apatemyidae

Genus	Species	Location	Stratigraphic position	Material	Images
Apatemys[25]	A. bellus	central and southern Wyoming	Bridger C	YPM 13512, partial mandible
	A. bellulus	southwestern and central Wyoming	Bridger C	YPM 13513, partial mandible USNM 22386, mandible

Esthonychidae

Genus	Species	Location	Stratigraphic position	Material	Images
Megalesthonyx[26]	M. hopsoni	Wyoming
Tillodon[27]	T. fodiens	Millersville, Uinta County, Wyoming
Trogosus[28]	T. castoridens	southwestern Wyoming
	T. gazini	Uinta County, Wyoming		USNM 364762, partial skeleton
	T. hyracoides	Granger Station, Sweetwater County, Wyoming
	T. latidens	Lincoln and Sweetwater counties, Wyoming
	T. vetulus	Lincoln and Sweetwater counties, Wyoming

Pantolestidae

Genus	Species	Location	Stratigraphic position	Material	Images
Pantolestes[29][30]	P. elegans	Wyoming
	P. intermedius	Wyoming
	P. longieundus	Wyoming
	P. natans	Wyoming
	P. phocipes	Wyoming

Creodontans

Hyaenodontidae

Genus	Species	Location	Stratigraphic position	Material	Images
Didelphodus[31]	D. altidens	southwestern Wyoming
Entemodon[30]	E. comptus	Honeycomb Buttes, Fremont County, Wyoming
Iridodon[32]	I. datzae	Cathedral Bluffs, Sweetwater County, Wyoming		UMMP 103465, mandible
Limnocyon[33]	L. cuspidens	Ice Castle, Uinta County, Wyoming		UMMP 103465, mandible
	L. medius	Henry's Fork Hill, Uinta County, Wyoming	Bridger D
	L. velox	southwestern Wyoming
	L. verus	Uinta County, Wyoming	Bridger C
Prolimnocyon[34]	P. antiquus	Sweetwater County, Wyoming
Proviverra[35]	P. americana	Wyoming
Sinopa[36][37][16][38][39]	S. aculeatus	Wyoming
	S. agilis	Uinta County, Wyoming
	S. eximia	Wyoming
	S. grangeri	Cottonwood Creek, Sublette County, Wyoming
	S. insectivorus	Cottonwood Creek, Sublette County, Wyoming
	S. major	southwestern Wyoming
	S. minor	Church Buttes, Uinta County, Wyoming
	S. pungens	Cottonwood Creek, Sublette County, Wyoming
	S. rapax	southwestern Wyoming
Tritemnodon[19]	T. hians	Wyoming
	T. strenuus	Davis Ranch, Johnson County, Wyoming

Oxyaenidae

Genus	Species	Location	Stratigraphic position	Material	Images
Aelurotherium[40]	A. bicuspis	Henry's Fork, Uinta County, Wyoming
	A. latidens	Grizzly Butte, Uinta County, Wyoming
Machaeroides[19]	M. eothen	Twin Buttes, Sweetwater County, Wyoming
	M. simpsoni	Davis Ranch, Johnson County, Wyoming
Patriofelis[41]	P. ferox	central and southwestern Wyoming
	P. ulta	southwestern Wyoming

Dinoceratans

Genus	Species	Location	Stratigraphic position	Material	Images
Bathyopsis[42]	B. fissidens	southwestern Wyoming	Bridger B.
Eobasileus[43]	E. cornutus	southwestern Wyoming
Uintatherium[44]	U. anceps	southwestern Wyoming	Bridger C & D.

Eulipotyphlans

Erinaceomorpha

Genus	Species	Location	Stratigraphic position	Material	Images
Talpavus[45]	T. nitidus	southwestern Wyoming	Bridger C	YPM 13511, fragmentary jaw

Geolabididae

Genus	Species	Location	Stratigraphic position	Material	Images
Centetodon[30]	C. bacchanalis	Hyopsodus Hill, Sublette County, Wyoming
	C. bembicophagus	southwestern Wyoming
	C. pulcher	southwestern Wyoming	Bridger C & D
Marsholestes[19]	M. dasypelix	Uinta County, Wyoming

Nyctitheriidae

Genus	Species	Location	Stratigraphic position	Material	Images
Nyctilestes[46]	N. serotinus	Uinta County, Wyoming
Nyctitherium[46]	N. gunnelli	Uinta County, Wyoming		SDSNH 110393, partial mandible
	N. priscus	Wyoming
	N. serotinum	central and southwestern Wyoming
	N. velox	Hyopsodus Hill, Sublette County, Wyoming

Leptictidans

Genus	Species	Location	Stratigraphic position	Material	Images
Hypictops[47]	H. syntaphus	Uinta County, Wyoming	Bridger D
Palaeictops[41]	P. bridgeri	central Wyoming

Macroscelids

Genus	Species	Location	Stratigraphic position	Material	Images
Scenopagus[48]	S. curtidens	western Wyoming
	S. edenensis	southwestern Wyoming
	S. priscus	western Wyoming

Mesonychids

Genus	Species	Location	Stratigraphic position	Material	Images
Harpagolestes[49]	H. immanis	southern Wyoming		AMNH 13143, a partial skull and jaws
	H. macrocephalus	Lincoln and Uinta counties, Wyoming
Mesonyx[50]	M. lanius	Wyoming
	M. obtusidens	Uinta County, Wyoming
Synoplotherium[51]	S. canius	Bitter Creek, Sweetwater County, Wyoming

Perissodactyls

Amynodontidae

Genus	Species	Location	Stratigraphic position	Material	Images
Orthocynodon[52]	O. antiquus	Wyoming

Brontotheriidae

Genus	Species	Location	Stratigraphic position	Material	Images
Eotitanops[53]	E. borealis	central Wyoming
Palaeosyops[54][55][2][53]	P. fontinalis	western Wyoming
	P. paludosus	central & southwestern Wyoming
	P. robustus	southwestern Wyoming
	P. ultimus
Telmatherium[25][56]	T. validum	Duncan Ranch, Fremont County, Wyoming	Bridger D
	T. validus	Sweetwater County, Wyoming	Bridger D	YPM 11120, a partial skull
Mesatirhinus[42]	M. megarhinus	Duncan Ranch, Fremont County, Wyoming		PU 10008

Equidae

Genus	Species	Location	Stratigraphic position	Material	Images
Oligotomus[57]	O. cinctus	Wyoming
Orohippus[58]	O. agilis	Wyoming		YPM 1268, partial skeleton
	O. ballardi	Wyoming		YPM 1268, partial skeleton
	O. major	Millersville, Uinta County, Wyoming		YPM 11270, fragmentary maxilla
	O. osbornianus	Blacks Fork, Uinta County, Wyoming
	O. procyoninus	Wyoming
	O. progressus	Wyoming		AMNH 12120, partial skull
	O. pumilus	southwestern Wyoming
	O. sylvaticus	Uinta County, Wyoming
	O. uintanus	Wyoming

Hyopsodontidae

Genus	Species	Location	Stratigraphic position	Material	Images
Hyopsodus[59]	H. minusculus	southern and central Wyoming	Bridger B
	H. lepidus	southwestern Wyoming	Bridger C
	H. paulus	southwestern Wyoming	Bridger B - D
	H. pygmaeus	Wyoming
	H. tonski	north and central Wyoming

Hyrachyidae

Genus	Species	Location	Stratigraphic position	Material	Images
Hyrachyus[60]	H. eximius	southwestern Wyoming
	H. minor	southwestern Wyoming
	H. paradoxus	Wyoming

Hyracodontidae

Genus	Species	Location	Stratigraphic position	Material	Images
Triplopus[61]	T. cubitalis	Wyoming
	T. obliquidens	Wyoming

Isectolophidae

Genus	Species	Location	Stratigraphic position	Material	Images
Isectolophus[62][63]	I. latidens	Lone Tree, Uinta County, Wyoming	Bridger D	PU 10251, fragmentary skull YPM 12563, partial skull
	I. radinskyi	Lone Spring, Uinta County, Wyoming	Bridger D

Tapiroidea

Genus	Species	Location	Stratigraphic position	Material	Images
Helaletes[64]	H. nanus	central & southwestern Wyoming		YPM 11080, partial jaws and cheek teeth YPM 11807, partial skeleton

Palaeanodonta

Genus	Species	Location	Stratigraphic position	Material	Images
Brachianodon[65]	B. westorum	southwestern Wyoming
Metacheiromys[66]	M. marshi	southwestern Wyoming	Bridger C

Pholidotans

Genus	Species	Location	Stratigraphic position	Material	Images
Tetrapassalus[67]	T. proius	southwestern Wyoming

Plesiadapiformes

Genus	Species	Location	Stratigraphic position	Material	Images
Alveojunctus[68]	A. minutus	Vass Quarry, Hot Springs County, Wyoming

Primates

Microsyopidae

Genus	Species	Location	Stratigraphic position	Material	Images
Microsyops[34][37][69]	M. angustidens	Blackrock Meadows, Teton County, Wyoming
	M. annectens	Sublette County, Wyoming
	M. elegans	southwestern Wyoming		YPM 11794, fragmentary mandible
	M. knightensis	Honeycomb Buttes, Sweetwater County, Wyoming		YPM 11794, fragmentary mandible
	M. scottianus	southern Wyoming		YPM 11794, fragmentary mandible
Uintasorex[citation needed]	U. parvulus	southwestern Wyoming	Bridger D	AMNH 12052, partial mandible

Notharctidae

Genus	Species	Location	Stratigraphic position	Material	Images
Notharctus[70][71]	N. robinsoni	southwestern Wyoming		UW 3007, fragmentary mandibles
	N. robustior	southwestern Wyoming	Bridger C & D	USNM 3750, fragmentary mandibles
	N. tenebrosus	southwestern Wyoming
	N. venticolus	Sweetwater County, Wyoming		AMNH 4715b, partial upper and lower jaws
Smilodectes[70]	S. gracilis	southwestern Wyoming		YPM 11800, partial mandible

Omomyidae

Genus	Species	Location	Stratigraphic position	Material	Images
Anaptomorphus[72][73]	A. aemulus	southwestern Wyoming		AMNH 5010, partial mandible
	A. westi	southwestern Wyoming
Gazinius[74]	G. amplus	central and southern Wyoming
	G. bowni	Uinta County, Wyoming
Hemiacodon[75][76]	H. engardae	Donna's Locality, Uinta County, Wyoming		UCM 67874, fragmentary mandible
	H. gracilis	Uinta County, Wyoming		YPM 11806, fragmentary mandible
Omomys[71]	O. carteri	southwestern Wyoming
Trogolemur[19]	T. myodes	Sweetwater County, Wyoming		AMNH 12399, partial mandible
Washakius[73]	W. insignis	southwestern Wyoming		ANSP 10332, partial mandible AMNH 55672

Rodentia

Cylindrodontidae

Genus	Species	Location	Stratigraphic position	Material	Images
Mysops[77]	M. fraternus	Green Locality, Sweetwater County, Wyoming
	M. minimus	Grizzly Buttes, Uinta County, Wyoming
	M. parvus	Grizzly Buttes, Uinta County, Wyoming

Ischyromyidae

Genus	Species	Location	Stratigraphic position	Material	Images
Acritoparamys[78]	A. wyomingensis	southern Wyoming
Leptotomus[78]	L. parvus	southwestern Wyoming
Mytonomys[79]	M. coloradensis	Van Houten's Locality, Park County, Wyoming
Paramys[80]	P. delicatior	southwestern Wyoming
	P. delicatus	southwestern Wyoming
Pseudotomus[81][82]	P. hians	Cottonwood Creek, Sublette County, Wyoming
	P. horribilis	Grizzly Buttes, Uinta County, Wyoming		AMNH 5025, skull
	P. robustus	southwestern Wyoming
Quadratomus[79]	Q. grandis	southwestern Wyoming
Thisbemys[78][79]	T. corrugatus	southern and central Wyoming
	T. perditus	Sweetwater County, Wyoming

Paramyidae

Genus	Species	Location	Stratigraphic position	Material	Images
Franimys[80]	F. buccatus	Wyoming

Reithroparamyidae

Genus	Species	Location	Stratigraphic position	Material	Images
Reithroparamys[80][79]	R. delicatissimus	western Wyoming
	R. huerfanensis	southern Wyoming

Sciuravidae

Genus	Species	Location	Stratigraphic position	Material	Images
Knightomys[79]	K. cuspidatus	Vass Quarry, Hot Springs County, Wyoming
	K. depressus	central and southern Wyoming
	K. huerfanensis	central and southern Wyoming
	K. senior	central and southern Wyoming
Taxymys[25]	T. lucaris	Sublette County, Wyoming
Tillomys[25]	T. parvidens	Grizzly Buttes, Uinta County, Wyoming
	T. senex	Sublette County, Wyoming

Metatherians

Herpetotheriidae

Herpetotheriids reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Herpetotherium[83]	H. innominatum	western Wyoming
	H. knighti	western Wyoming
Peratherium[83]	P. comstocki	central Wyoming
	P. marsupium	southwestern Wyoming

Peradectidae

Peradectids reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Armintodelphys[83]	A. blacki	Lightning Butte, Sweetwater County, Wyoming
Peradectes[83]	P. chesteri	southwestern Wyoming

Birds

Gruiformes

Gruiformes reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Aletornis[84]	A. bellus	Grizzly Buttes, Uinta County, Wyoming
	A. gracilis	Henry's Fork, Sweetwater County, Wyoming
	A. nobilis	Grizzly Buttes, Uinta County, Wyoming
	A. pernix	Henry's Fork, Sweetwater County, Wyoming
	A. venustus	Henry's Fork, Sweetwater County, Wyoming

Strigiformes

Owls reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Minerva[85][86]	M. leptosteus	Grizzly Buttes, Uinta County, Wyoming		YUPM 512, partial tibia
	M. saurodosis	Lodge-Pole Trail, Uinta County, Wyoming		ANSP 9131, partial humerus

Fish

Amiidae

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]

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Amia[88]	A. (Pa.) cornsonii[89]	"Upper Green River", southwestern Wyoming		USNM 3961, a centrum and dentary fragment (holotype) USNM 5476, 5475 and 3960 isolated centra (plesiotypes)	Nomen dubium per Grande & Bemis (1998) as Amiinae indeterminate[87]
	A. depressus	"Southwestern Wyoming"		Isolated "vertebrae and cranial bones" (Holotype, now lost?)[87]	Nomen dubium per Grande & Bemis (1998) as Amiinae indeterminate[87]
	A. (H.) elegans[90]	Dry Creek, Uinta County, Wyoming		ANSP 5580, isolated centrum	Nomen dubium per Grande & Bemis (1998) as Amiinae indeterminate[87]
	A. (Pr.) laevis[91][92]	"Cottonwood Creek", Wyoming		USNM 3968 - Fragmentary premaxilla, dentary, quadrate, cranium, branchiostegal, pterygoid, and two centra	Nomen dubium per Grande & Bemis (1998) as Amiinae indeterminate[87]
	A. newberrianus	"Southwestern Wyoming"		ANSP 5632, vertebral centrum (Now lost?)[87]	Nomen dubium per Grande & Bemis (1998) as Amiinae indeterminate[87]
	A. (Pa.) plicatus	Wyoming		AMNH 2539 - skull bones and vertebrae (syntypes) USNM 3958 - skull bones and vertebrae (syntypes)	Nomen dubium per Grande & Bemis (1998) as Amiinae indeterminate[87]
	A. (Pa.) sclerops	"bluffs of Cottonwood Creek", Wyoming		USNM 3965, partial left dentary	Nomen dubium per Grande & Bemis (1998) as Amiinae indeterminate[87]
	A. (Pr.) uintaensis	Dry Creek Cañon, Uinta County, Wyoming		ANSP 3151, 5558, 5622, 8044 - vertebral centra, a basioccipital (Syntypes)	Nomen dubium per Grande & Bemis (1998) as Amiinae indeterminate[87]

Ariidae

Genus	Species	Location	Stratigraphic position	Material	Images
Rhineastes[51]	R. peltatus	Wyoming
	R. smithii	Wyoming

Lepisosteidae

Genus	Species	Location	Stratigraphic position	Material	Images
Lepisosteus[93][94]	L. atrox	Wyoming
	L. simplex	Wyoming

Osteoglossidae

Genus	Species	Location	Stratigraphic position	Material	Images
Phareodus[95]	P. encaustus	Wyoming
	P. testis	Wyoming

Reptiles

Crocodilia

Crocodilians reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Crocodilus[96]	C. elliottii	Wyoming
	C. grypus	Wyoming
	C. parvus	Wyoming
	C. sulciferus	Wyoming
Boverisuchus[97]	B. vorax	Wyoming
Borealosuchus[98]	B. wilsoni	Wyoming
Allognathosuchus[97]	A. polyodon	Wyoming
Brachyuranochampsa[97]	B. zangerli	Wyoming

Squamates

Anguidae

Anguids reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Glyptosaurus[99]	G. sphenodon	Henry's Fork, Sweetwater County, Wyoming		YPM 1051, partial maxilla and two teeth
	G. sylvestris	Big Horn and Uinta counties, Wyoming		YPM 526, left frontal YPM 521, fragmentary skull and jaws; several cervical and dorsal vertebrae; and several osteoderms YPM 522, a skull fragment; frontal; and two body scutes YPM 523, patch of cranial scutes
Paraglyptosaurus[100]	P. princeps	southwestern Wyoming		YPM 524, partially-complete skull and jaw; dermal scutes USNM 6004, partially-complete skull YPM 525, partially-complete frontal bones
Xestops[101]	X. vagans	southwestern Wyoming		YPM 541, partial skeleton AMNH 3819, left frontal

Boidae

Boas reported from the Bridger Formation[102]
Genus	Species	Location	Stratigraphic position	Material	Images
Boavus	B. brevis	Grizzly Buttes, Uinta County, Wyoming		PMNH 468, a thoracic vertebra
	B. occidentalis	Grizzly Buttes, Uinta County, Wyoming		PMNH 511, a dorsal vertebra YPM 467, vertebra YPM 2765, vertebra YPM 2766, vertebra
Lithophis	L. sargenti	Grizzly Buttes, Uinta County, Wyoming		YPM 2719, a thoracic vertebra
Protagras	P. lacustris	Cottonwood Creek, Sublette County, Wyoming

Chamaeleonidae

Chameleons reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Tinosaurus[103]	T. pristinus	Uinta County, Wyoming		PAS 9134, partial dentary and eight teeth
	T. stenodon	Henry's Fork Hill, Sweetwater County, Wyoming		YUM 615, partial dentary and three teeth

Rhineuridae

Rhineurids reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Lestophis[104]	L. anceps	Grizzly Buttes, Uinta County, Wyoming		YPM 520, vertebra
	L. crassus	Marsh Creek, Uinta County, Wyoming		YPM 531, cervical vertebra
Spathorhynchus[105]	S. fossorium	Twin Buttes, Sweetwater County, Wyoming	Bridger B

Teiidae

Teiids reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Iguanavus[106]	I. exilis	Henry's Fork, Sweetwater County, Wyoming

Varanidae

Varanids reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Saniwa[107]	S. ensidens	southern Wyoming		USNM 2185, partial skeleton and skull LACM CIT 5117, four vertebrae YPM 609, partial skeleton and a tooth YPM 610, fragmentary skeleton including several vertebrae YPM 611, partial vertebra YPM 612, partial skeleton
	S. major	Lodge-Pole Trail, Uinta County, Wyoming

Testudines

Baenidae

Baenids reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Baena[108]	B. arenosa	Uinta County, Wyoming		USNM 103, partial carapace AMNH 1675, carapace AMNH 5971, skull; carapace; vertebrae AMNH 5977, mostly-complete skeleton ANSP 10055, carapace CM 3227, partial carapace CM 3406, nearly-complete carapace
Chisternon[109]	C. hebraicum	Cottonwood Creek, Sublette County, Wyoming	Bridger B	USNM 2275, partial carapace
	C. undatum	Uinta County, Wyoming

Carettochelyidae

Carettochelyids reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Anosteira[110]	A. ornata	southwestern Wyoming
	A. radulina	Ham's Fork, Lincoln County, Wyoming		USNM 4096, partial carapace

Dermatemydidae

Dermatemydids reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Baptemys[111]	B. wyomingensis	Natrona and Uinta Counties, Wyoming		AMNH 5934, complete carapace; fragmentary cervical vertebrae; pelvis AMNH 5967, partially-complete skull; crushed carapace YPM 484, nearly complete skull; crushed carapace with complete plastron; partial limb bones; one complete toe

Emydidae

Emydids reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Emys[107][25][112][113]	E. jaensi	Sweetwater County, Wyoming		USNM 962, partial carapace
	E. latilabiatus	Blacks Fork, Uinta County, Wyoming
	E. stevensonianus	Fort Bridger, Uinta County, Wyoming		USNM 963, partial carapace USNM 965, partial carapace USNM 967, partial carapace
	E. wyomingensis	Fort Bridger, Uinta County, Wyoming		ANSP 9777, plastron fragment
Hybemys[114]	H. arenarius	Little Sandy Creek, Sublette County, Wyoming

Geoemydidae

Geoemydids reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Echmatemys[115]	E. haydeni	Levett Creek Quarry, Uinta County, Wyoming		USNM 109, partial carapace
	E. septaria	Uinta County, Wyoming
	E. wyomingensis	Uinta County, Wyoming

Testudinidae

Testudinids reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Hadrianus[72][116]	H. allabiatus	Cottonwood Creek, Sublette County, Wyoming	Bridger B
	H. corsoni	Cottonwood Creek, Sublette County, Wyoming	Bridger B	ANSP 10050, plastron
	H. octonaria	Cottonwood Creek, Sublette County, Wyoming	Bridger B
	H. quadratus	Cottonwood Creek, Sublette County, Wyoming	Bridger B

Trionychidae

Trionychids reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Apalone[117]	A. extensa	Grizzly Buttes, Uinta County, Wyoming		AMNH 5951, partial carapace
	A. heteroglypta	Wyoming
	A. postera	Uinta County, Wyoming	Bridger C	AMNH 6133, partial carapace
	A. trionychoides	Cottonwood Creek, Sublette County, Wyoming		USNM 4094, partial carapace
Axestemys[118]	A. byssina	Blacks Fork, Sweetwater County, Wyoming		USNM 4089, partial skeleton USNM 12589, fragmentary skull and partial plastron
	A. cerevisia	Opal, Lincoln County, Wyoming		UW 2382, carapace with plastron; cervical vertebra; partial girdles
	A. salebrosa	Dry Creek, Uinta County, Wyoming	Bridger C	AMNH 3941, partial carapace
	A. uintaensis	Little Dry Creek, Uinta County, Wyoming
Hummelichelys[119]	H. annae	Sweetwater County, Wyoming		FMNH P 27241, nearly-complete carapace with plastron
	H. ellipticus	Grizzly Buttes, Uinta County, Wyoming		AMNH 1117, carapace
	H. grangeri	Cottonwood Creek, Sublette County, Wyoming		AMNH 3942, partial carapace
	H. guttatus	Uinta County, Wyoming
Plastomenus[36]	P. molopinus	Grizzly Buttes, Uinta County, Wyoming		AMNH 6072, fragmentary carapace
	P. oedemius	Sublette and Uinta Counties, Wyoming	Bridger B	AMNH 3937, a partial carapace
	P. tantillus	Cottonwood Creek, Sublette County, Wyoming	Bridger B	AMNH 6018, partial carapace
	P. thomasi	Sublette and Uinta Counties, Wyoming		AMNH 5980, nearly-complete carapace with plastron
	P. visendus	Rattlesnake Hills, Fremont County, Wyoming		AMNH 1895, carapace
Platypeltis[120][121]	P. serialis
	P. trepida	Grizzly Buttes, Uinta County, Wyoming		AMNH 5925, partial carapace
Trionyx[122]	T. concentricus	Cottonwood Creek, Sublette County, Wyoming		AMNH 1049, partial carapace

Incertae sedis

Reptiles of uncertain placement reported from the Bridger Formation
Genus	Species	Location	Stratigraphic position	Material	Images
Naocephalus[123]	N. porrectus	Cottonwood Creek, Sublette County, Wyoming	Bridger B

See also

• List of fossiliferous stratigraphic units in Wyoming
• Paleontology in Wyoming