TABLE 1. CA-TIMS U-Pb zircon data. Zircon dissolution and chemistry were adapted from methods developed by Krogh (1973), Parrish et al. (1987) and Mattinson (2005). All zircons were chemically abraded (CATIMS). Final dissolutions were spiked with a mixed 205Pb/ 23U/ 235U tracer (ET535). Pb and UO2 from zircons were loaded onto single rhenium filaments with silica gel without any ion exchange cleanup; isotopic compositions were measured in single Daly-photomultiplier mode on a Micromass Sector 54 thermal ionization mass spectrometer at the University of Wyoming. Mass discrimination for Pb was 0.245 ± 0.10 %/amu for Daly analyses based on replicate analyses of NIST SRM 981. U fractionation was determined internally during each run. Procedural blanks ranged from 0.55 to 4 picograms Pb during the course of the study. U blanks were consistently less than 0.1 pg. Isotopic composition of the Pb blank was measured as 18.419 ± 1.37, 15.369 ± 0.63 and 37.228 ± 2.59 for 206Pb/ 204Pb, 207Pb/ 204Pb, and 208Pb/ 204Pb, respectively. Concordia coordinates, intercepts, uncertainties and Concordia Ages were calculated using PbMacDat and ISOPLOT programs (based on Ludwig 1988, 1991, 1998); initial Pb isotopic compositions for zircon were estimated by Stacey and Kramers (1975) model. The decay constants used by PbMacDat are those recommended by the I.U.G.S. Subcommission on Geochronology (Steiger and Jäger, 1977): 0.155125 x 10 -9/yr for 238U, 0.98485 x 10-9/yr for 235U and present-day 238U/ 235U = 137.88.

  Corrected atomic ratios  
  Weight
(µg)
U
(ppm)
sample Pb cPb Pb* Th 206 Pb 208 Pb 206 Pb/ 238 Pb 207 Pb/ 206Pb 207Pb/206Pb 206Pb/238U 207 Pb/ 235 U
Age
(Ma)
Rho
Sample (ppm) (pg) (pg) Pbc U 204Pb 206Pb (rad.) % err (rad.) % err (rad.) % err Age
(Ma)
err  
PCM3 Aug14-07 volcanic tuff   46.94 ±0.14 [0.15] Ma weighted mean 206 Pb/ 238 U date, 2s, without [with] decay-const. errs (MSWD 0.48), 6 points
07 ash sG* 0.4 152 1.5 0.6 1.3 0.4 0.8 42 0.3 0.00755 -2.51 0.0569 -38.15 0.0546 -35.91 48.48 ±1.22 56.2 0.9
07 ash sK* 0.7 373 3.1 2.2 0.6 1.4 0.7 101 0.22 0.00748 -0.73 0.0485 -12.57 0.047 -11.93 48.03 ±0.35 48.1 0.88
07 ash sI* 0.6 630 5.5 3.4 0.9 2.7 0.9 164 0.31 0.00737 -0.42 0.0502 -6.78 0.0494 -6.42 47.33 ±0.20 49.7 0.87
07 ash sD 0.8 322 3 2.5 1.1 2.2 1.2 130 0.4 0.00732 -0.55 0.0491 -8.95 0.0486 -8.48 47.04 ±0.26 48.6 0.87
07 ash sA 2.8 73 0.7 1.9 3.1 0.6 1.2 50 0.44 0.00732 -1.91 0.0522 -30.6 0.0517 -28.9 47 ±0.90 51.6 0.9
07 ash sN 0.2 641 5.4 1.1 0.6 1.9 0.8 126 0.23 0.00731 -0.52 0.0419 -10.01 0.0416 -9.57 46.93 ±0.24 41.7 0.87
07 ash sB 1.4 241 2.2 3.1 3.1 1 1.1 70 0.41 0.0073 -1.18 0.0533 -18.4 0.0529 -17.3 46.91 ±0.55 52.7 0.9
07 ash sL 0.5 358 3 1.4 1.6 1.5 0.8 104 0.23 0.0073 -0.69 0.0411 -13.64 0.0409 -13.03 46.87 ±0.32 40.9 0.89
07 ash sH 1.6 83 0.8 1.2 1.2 0.5 1.2 45 0.38 0.00721 -2.27 0.0474 -39.51 0.0478 -37.48 46.28 ±1.05 47.1 0.9
07 ash sM* 0.4 100 10.7 4.3 0.6 7.2 0.5 443 0.17 0.09959 -0.21 0.8355 -1.83 0.0608 -1.7 612 ±1.3 616.7 0.62
PCM3 Aug14-04 volcanic tuff   47.31 ±0.06 [0.08] Ma weighted mean 206Pb/238U date, 2s, without [with] decay-const. errs (MSWD 0.97), 4 points
04 euh sC 1.1 142 1.1 1.3 1.3 0.3 0.4 38 0.17 0.00755 -3.14 0.0639 -42.49 0.0614 -39.69 48.46 ±1.52 62.9 0.9
04 euh sA 0.2 3294 27 6.6 4 1.9 0.7 126 0.24 0.00739 -0.75 0.0518 -9.22 0.0508 -8.7 47.44 ±0.35 51.3 0.71
04 ash sD 2.8 927 8.3 23.2 3.5 17.6 1.1 929 0.36 0.00737 -0.14 0.0481 -1.16 0.0474 -1.1 47.31 ±0.07 47.7 0.51
04 ash sA 1.4 735 6 8.4 2.4 3.6 0.7 222 0.24 0.00736 -0.35 0.0475 -5.38 0.0468 -5.1 47.28 ±0.16 47.2 0.8

Abbreviations and notes
Sample: euh = euhedral; ash = ash-fall zircon morphology; s = single grain; *excluded from age calculations.
Weight: represents estimated weight after first step of CATIMS zircon dissolution and is only approximate. U and Pb concentrations are based on this weight and are useful for internal comparisons only. Picograms (pg) sample and common Pb from the second dissolution step are measured directly, however, and are accurate.
Sample Pb: sample Pb (radiogenic + initial) corrected for laboratory blank.
cPb: total common Pb. All was assigned to laboratory blank.
Pb*/Pbc: radiogenic Pb to total common Pb (blank + initial).
Corrected atomic ratios: 206Pb/204Pb corrected for mass discrimination and tracer, all others corrected for blank, mass discrimination, tracer and initial Pb, values in parentheses are 2 sigma errors in percent. 206Pb/238Pb ratios and dates corrected for Th disequilibrium assuming Th/U magma of 2.2.
Rho: 206 Pb/238U versus 207Pb/235U error correlation coefficient.

 

TABLE 2. Paleomagnetic data for samples from two stratigraphic levels in uppermost Bridger Formation. PCM6Sept15-02 and PCM6Sept15-03 are from the base of white tuffaceous sandstone in the TBM type section on the southwest flank of Cedar Mountain (Figure 1). PCM7Sept15-01 is from the Basal E tuff in the uppermost Twin Buttes Member (Bridger D) on west flank of Sage Creek Mountain. Latitude and Longitude are relative to WGS84 datum. Stratigraphic level (in meters) of site relative to the base of the TBM (= Basal E limestone, Figure 1). Decstrat and Incstrat are declination and inclination of Characteristic Remanent Magnetization in stratigraphic coordinates, α95 is 95% cone of confidence, K is value of precision parameter, R is length of resultant vector, VGP long/lat are longitude and latitude of virtual geomagnetic pole.

Site Lat
(degree)
Long
(degree)
Strat Level
(m)
Dec strat Inc strat a 95 K N R VGP long VGP lat
PCM6Sept15-02 41.08888 -110.08462 74 347.86 46.24 28 20.45 3 2.9 110.09 73.2
PCM6Sept15-03 41.08888 -110.08462 74 316.98 34.72 30.58 17.31 3 2.88 142.09 47.38
PCM71501 41.12615 -110.13862 -8 28.98 62.73 19.3 41.87 3 2.95 322.08 68.58

 

TABLE 3. Measurements (in mm) of Didelphimorphia from TBM (a = approximate; b = broken dimension; p. = partial).

Taxon/Specimen number Position ap tr tra trp
Herpetotherium knighti          
SDSNH 110429 M1 2.06 2.01 - -
DMNH 75286 M1 2.28 2.06a - -
UCM 68793 M2 2.08 2.26 - -
UCM 70637 M2 2.13 2.21 - -
UCM 70639 M2 2.03 2.32 - -
UCM 95783 M2 2.10 2.29 - -
SDSNH 110430 p. M1 or 2 2.10b - - -
SDSNH 110431 p. M1or 2 - 2.00b - -
UCM 68622 p. M2 or 3 - 2.56 - -
UCM 68794 M3 2.10 2.41 - -
UCM 70770 M3 2.20 2.41 - -
UCM 69973 p. M3 2.10b - - -
UCM 95784 M4 1.99 2.15 - -
UCM 95797 p2 1.61 0.54 - -
DMNH 75324 dp3 1.64 - 0.64 0.85
UCM 68902 dp3 2.02 - 0.93 1.03
UCM 68908 p3 1.90 0.98 - -
UCM 68937 p3 1.85 0.85 - -
UCM 95792 m1 1.90 - 0.98 1.05
UCM 70636 m2 or 3 2.20 - 1.26 1.35
UCM 70977 m2 or 3 2.38 - 1.31 1.31
UCM 78454 m2 or 3 2.15 - 1.28 1.23
UCM 95785 m2 or 3 2.33 - 1.26 1.39
UCM 95790 m2 or 3 2.28 - 1.28 1.26
SDSNH 110427 p. m2 or 3 2.39 - 1.33 -
UCM 68901 p. m2 or 3 2.38b - 1.41 -
SDSNH 110339 m2 2.08 - 1.18 1.23
UCM 68574 m2 2.08 - 1.20 1.23
  m3 2.18 - 1.26 1.26
UCM 95780 m3 2.26 - 1.26 1.23
  m4 2.26 - 1.23 1.09
UCM 67896 m4 2.33 - 1.23 1.03
UCM 95793 m4 2.38 - 1.31 1.05
Peradectes chesteri          
DMNH 75275 dP3 1.39 1.33 - -
UCM 68427 M1 1.34 1.49 - -
SDSNH 110418 p. M1 - 1.27b - -
UCM 95781 M2 1.31 1.49 - -
  M3 1.28 1.59 - -
UCM 78458 m2 or 3 1.41 - 0.72 0.72
Peradectes californicus          
SDSNH 110432 m2 or 3 1.28 - 0.77 0.72

 

 

TABLE 4. Faunal characterization of Ui1a faunas (revised after Murphey and Kelly, 2017, table 5). Taxonomic lists of mammals of Uintan biochron Ui1a from TBM and the basal Tertiary Conglomerate Local Fauna (BTC) of lower member of the Devil's Graveyard Formation, Texas, along with taxa from lower in Bridger Formation (Br2 or Br3) that are hold overs in the TBM and BTC, and taxa that range-through to Ui1b or later. References: Leidy, 1872 1; Marsh, 1872b 2; Matthew, 1909 3; Troxell, 1923b 4; Wilson, 1937 5; McKenna and Simpson, 1959 6; Wood, 1959 7, 1973 8; Robinson, 1968 9; Szalay, 1969 10, 1976 11; West, 1974 12; Gazin, 1976 13; Krishtalka, 1976 14; Lillegraven et al., 1981 15; West and Hutchinson, 1981 16; Wilson and Schiebout, 1984 17; West, 1982 18; Wilson, 1984 19, 1986 20; Krishtalka, personal communication in Wilson, 1986 21; McCarroll et al., 1996a 22; Walsh, 1996b 23; Asher et al., 2002 24; Turnbull, 2002 25; Williams and Kirk, 2008 26; Gunnell et al., 2008 27, 2009 28; Mihlbachler, 2008 29; Murphey and Dunn, 2009 30; Campisano et al., 2014 31; Kelly and Murphey, 2016a 32; Murphey and Kelly, 2017 33; this paper 34. LRD, lowest range datum (= first appearance). Index species, taxa restricted to Ui1a. N, number of taxa.

Designation N TBM Taxa N BTC Taxa
Index species 5 Hemiacodon engardae 30 0  
    Nyctitherium gunnelli 33    
    Entomolestes westgatei 33    
    Elymys ? emryi 32    
    Merycobunodon ? walshi 33    
Genus LRD 5 Metanoiamys 33 2 Prolapsus 8
    Wickia 33   Leptoreodon 19
    Triplopus 33    
    Epihippus 33    
    Merycobunodon 33    
Species LRD 16 Peradectes californicus 34 4 Prolapsus juntionalis 8
    Nyctitherium gunnelli 33   Prolapsus sp. 8
    Entomolestes westgatei 33   Pareumys boskeyi 8
    Sespedectinae, genus indet. 33   Leptoreodon pusillus 19
    unnamed eulipotyphlan sp. 33    
    Hemiacodon engardae 30    
    Microparamys sp. 32    
    new cylindrodont or ailuravine sp. 32    
    cf. Pareumys sp. 32    
    sciuravid sp. A 32    
    Metanoiamys sp. 32    
    Elymys ? emryi 32    
    Wickia sp., cf. W. brevirhinus 33    
    Triplopus sp., cf. T. obliquidens 33    
    Epihippus sp., cf. E. gracilis 33    
    Merycobunodon ? walshi 33    
Species also known from Br2 or Br3 29 Peradectes chesteri 34 14 Scenopagus priscus 21
    Herpetotherium knighti 34   Scenopagus sp. 21
    Herpetotherium marsupium 34   Entomolestes ? sp. 21
    Apatemys bellulus 4, 13, 33   Centetodon pulcher 21
    Apatemys rodens 4, 33   Nyctitherium velox 21
    Uintasorex parvulus 3   cf. Pantolestes sp. 21
    Microsyops annectans 10   Microsyops annectans 18
    Notharctus robustior 1, 28, 32   Omomys carteri 18, 25
    Trogolemur myodes 3   Notharctus tenebrosus 18, 25
    Omomys carteri 11   Microparamys minutus 8
    Washakius insignis 11   Thisbemys plicatus 8
    Scenopagus priscus 6   Thisbemys plicatus 8
    Scenopagus curtidens 3, 6   Hyopsodus paulus 18
    Centetodon bemicophagus 15   Hyrachyus ? sp., cf. H. modestus 17
    Centetodon pulcher 15   Helohyus sp . 18
    Nyctitherium velox 9, 14   Hyrachyus ? sp., cf. H. modestus 17
    Pontifactor bestiola 12    
    unnamed apternodontid sp. 24    
    Viverravus gracilis 2, 3    
    Paramys sp., cf. P. delicatior 16    
    Microparamys minutus 5    
    Thisbemys corrugatus 7    
    Sciuravus nitidus 4    
    Tillomys senex 4    
    Tillomys ? parvidens 4    
    Taxymys lucaris 4    
    Hyopsodus lepidus 33    
    Uintatherium anceps 33    
    Homacodon sp., cf. H. vagans 33    
Species range through to Ui1b or later 15 Peradectes californicus 34 11 Microsyops annectans 20
    Herpetotherium knighti 34   Omomys carteri 23, 27
    Herpetotherium marsupium 34   Ourayia uintensis 18, 28
    Uintasorex parvulus 28   Macrotarsius sp. 18, 26
    Microsyops annectans 31   Microparamys minutus 31
    Notharctus robustior 22   Thisbemys plicatus 8, 28
    Omomys carteri 23   Prolapsus juntionalis 8, 28
    Scenopagus priscus 28   Pareumys boskeyi 8, 28
    Scenopagus curtidens 28   Triplopus implicatus 17, 28
    Tillomys senex 28   Helohyus sp. 28
    Uintatherium anceps 25   Leptoreodon pusillus 19
    Wickia brevirhinus 29    
    Epihippus gracilis 28    
    Triplopus obliquidens 28    

 

 

TABLE 5. Faunal Characterization of the Ui1b (revised after Gunnell et al., 2009, table 7). Sand Wash Basin taxa records were removed because the relative stratigraphic positions of localities are undetermined and the taxa need to be reevaluated with a detailed systematic analysis, except for the Bridgerian locality 20 of West and Dawson (1975) from below Robin's Blue Egg Marker bed. HRD, highest range datum (= last occurrence). LRD, lowest range datum (= first appearance). Index species, taxa restricted to Ui1b. AT, Adobe Town middle member, Washakie Formation. BB, Blacks Fork Member, Bridger Formation. FS, Friars Formation. FTT, "Foggy Day beds," Tepee Trail Formation. HTT, "Holy City beds," Tepee Trail Formation. TB, Twin Buttes Member, Bridger Formation.

Designation Taxa
Index species Achaenodon insolens (AT) Patriolestes novaceki (F)
Achaenodon robustus (AT, F, FTT) Protoreodon sp. nov. Walsh, 1996b (F)
Aethomylos venustus (F) Pseudotomas californicus (F)
Antiacodon venustus (F) Pseudotomas littoralis (F)
Apatemys downsi (F) Sciuravus powayensis (F)
Centetodon aztecus (F) Stockia powayensis (F)
Crypholestes vaughni (F) Triplopus cubitalis (AT)
Hesperolemur actius (F) Washakius woodringi (F)
Leptoreodon major (F) Uintaceras sp. (HTT)
Merycobunodon littoralis (F) Uintaparamys caryophilus (F)
Metarhinus pater (F) Uintasorex montezumicus (F)
Microsyops kratos (F) Uriscus californicus (F)
Genus LRD Achaenodon (AT, F) Parahyus (F)
Aethomylos (F) Protoptychus (AT)
Amynodon (F, AT) Protoreodon (F)
Batodonoides (F) Protylopus (AT)
Crypholestes (F) Oligoryctes (F)
Eobasileus (AT, F) Ourayia (F)
Eomoropus (AT) Sphenocoelus (AT)
Hesperolemur (F) Stockia (F)
Metarhinus (F, AT) Tapocyon (F)
Patriolestes (F) Uintaceras (AT, HTT)
Poebrodon (AT) Uriscus (F)
Genus HRD Antiacodon (F) Patriolestes (F)
Crypholestes (F) Pauromys (F)
Helohyus (F) Parahyus (F)
Hesperolemur (F) Stockia (F)
Merycobunodon (F) Uintasorex (F)
Microsyops (F) Uriscus (F)
Omomys (F) Washakius (F)
Palaeictops (F)  
Species LRD and that range through to Ui2 or later Amynodon reedi (F) Uintaceras radinskyi (AT)
Batodonoides powayensis (F) Ourayia sp. nov. Walsh, 1996b (F)
Eobasileus cornutus (AT) Parahyus sp. (F)
Eomoropus amarorum (AT) Pareumys grangeri (F)
Limnocyon potens (AT) Protoptychus hatcheri (AT)
Metarhinus fluviatilis (F) Protylopus petersoni (AT)
Species also known from Br2 and/or Br3 Apatemys bellus (TB, BB) Notharctus robustior (TB)
Centetodon bemicophagus (TB, BB) Omomys carteri (TB, BB)
Herpetotherium knighti (TB, BB) Peradectes chesteri (TB, BB)
Herpetotherium marsupium (TB, BB) Scenopagus priscus (TB, BB)
Microparamys minutus (TB, BB) Uintatherium anceps (TB)
Microsyops annectens (TB, BB)