TABLE 1. Measurements (in mm) of Apatemyidae from TBM. Abbreviations are: ap = greatest anteroposterior length; b = broken dimension; p. = partial; tr = greatest transverse width; tra = anterior transverse (trigonid) width; trp = posterior transverse (talonid) width.
| Taxon/Specimen number | Position | ap | tr | tra | trp |
| Apatemys bellulus | |||||
| UCM 70967 | M1 | 1.96 | 1.90 | - | - |
| UCM 95804 | m1 | 1.87 | - | 1.08 | 1.13 |
| UCM 68923 | m2 | 1.85 | - | 1.39 | 1.31 |
| UCM 68424 | p. m3 | 1.97 | - | - | 1.21 |
| UCM 70676 | m3 | 1.92 | - | 1.23 | 1.05 |
| UCM 95807 | m3 | 2.00 | - | 1.26 | 1.16 |
| Apatemys rodens | |||||
| UCM 68580 | M1 | 2.48 | 2.08 | - | - |
| UCM 68970 | M3 | 1.36 | 2.37 | - | - |
| SDSNH 110342 | p. M3 | 1.37b | 2.06b | - | - |
| UCM 66324 | p. m3 | 2.79 | - | - | 1.74 |
| UCM 95801 | p. m3 | 2.90 | - | - | 1.80 |
| UCM 95805 | m3 | 2.82 | - | 2.13 | 1.74 |
TABLE 2. Measurements (in mm) of Lipotyphla and Carnivoramorpha from TBM. Abbreviations are: ap = greatest anteroposterior length; b = broken dimension; p. = partial; tr = greatest transverse width; tra = anterior transverse (trigonid) width; trp = posterior transverse (talonid) width.
| Taxon/Specimen number | Position | ap | tr | tra | trp |
| Scenopagus priscus | |||||
| UCM 95683 | m1 or 2 | 1.40 | - | 1.02b | 1.05 |
| SDSNH 110345 | m3 | 1.35 | - | 0.85 | 0.67 |
| Scenopagus curtidens | |||||
| UCM 68966 | M1 | 1.77 | 2.49 | - | - |
| SDSNH 110344 | dp4 | 1.60 | - | 0.91 | 1.00 |
| UCM 70677 | p. m1 or 2 | 1.88 | - | 1.32 | - |
| UCM 95684 | m1 or 2 | 1.80 | - | 1.49 | 1.51 |
| UCM 95685 | m1 or 2 | 1.74 | - | 1.46 | 1.49 |
| UCM 68968 | m3 | 1.60 | - | 1.12 | 0.94 |
| Sespedectinae, genus undet. | |||||
| SDSNH 110343 | p. m1 or 2 | 1.36b | - | 1.44 | - |
| Entomolestes westgatei n. sp. | |||||
| UCM 68540 | p4 | 0.90 | - | 0.67 | 0.62 |
| UCM 95686 | p4 | 0.95 | - | 0.71 | 0.58 |
| m1 | 1.56 | - | 0.93 | 0.95 | |
| UCM 95687 (holotype) | p4 | 0.90 | - | 0.72 | 0.62 |
| m1 | 1.59 | - | 0.94 | 0.95 | |
| UCM 67884 | p. m1 | - | - | 0.90 | 0.88 |
| m2 | 1.41 | - | 0.93 | 0.93 | |
| m3 | 1.08 | - | 0.64 | 0.57 | |
| UCM 78746 | p. m1 | - | - | 0.93 | - |
| UCM 68423 | m2 | 1.39 | - | 0.91 | 0.93 |
| UCM 68973 | m2 | 1.36 | - | 0.95 | 0.87 |
| Centetodon bemicophagus | |||||
| UCM 68681 | P4 | 1.46 | 1.49 | - | - |
| SDSNH 110347 | M3 | 0.93 | 1.90 | - | - |
| SDSNH 110391 | p4 | 1.21 | - | 0.67 | 0.67 |
| UCM 68899 | m1 or 2 | 1.49 | - | 1.00 | 0.85 |
| UCM 71128 | m1 or 2 | 1.34 | - | 0.77 | 0.70 |
| DMNH 75256 | m1 or 2 | 1.50 | - | 0.85 | 0.70 |
| DMNH 75257 | m3 | 1.46 | - | 0.85 | 0.70 |
| Centetodon pulcher | |||||
| UCM 67889 | p4 | 1.55 | - | 0.92 | 0.87 |
| UCM 68534 | p4 | 1.59 | - | 0.93 | 0.87 |
| UCM 95767 | p4 | 1.79 | - | 0.93 | 0.93 |
| m1 | 2.01 | - | 1.28 | 1.18 | |
| UCM 95768 | m1 or 2 | 1.83 | - | 1.25 | 1.16 |
| UCM 68963 | p1 | 1.19 | 0.52 | - | - |
| p4 | 1.59 | - | 1.10 | 0.93 | |
| m1 | 1.75 | - | 1.31 | 1.20 | |
| m2 | 1.70 | - | 1.21b | 1.15 | |
| m3 | 1.68 | - | 1.10b | 0.90 | |
| DMNH 75327 | m2 | 1.65 | - | 1.03 | 0.87 |
| UCM 69968 | m3 | 1.55 | - | 1.03 | 0.93 |
| UCM 95682 | m3 | 1.59 | - | 1.05 | 0.87 |
| Nyctitherium gunnelli n. sp. | |||||
| UCM 95769 | P4 | 2.08 | 2.54 | - | - |
| SDSNH 110393 (holotype) | p4 | 2.09 | - | 0.93 | 1.00 |
| m1 | 2.23 | - | 1.14 | 1.22 | |
| m2 | 2.08 | - | 1.23 | 1.27 | |
| Nyctitherium velox | |||||
| DMNH 75292 | M2 | 1.71 | 2.27 | - | - |
| UCM 68581 | M2 | 1.58 | 2.13 | - | - |
| UCM 95771 | M2 | 1.62 | 2.11 | - | - |
| DMNH 75290 | p. M1 or 2 | - | 2.10b | - | - |
| DMNH 75291 | M3 | 1.21 | 1.90 | - | - |
| UCM 68967 | m1 | 1.72 | - | 1.08 | 1.13 |
| SDSNH 110409 | p. m2 | 1.60 | - | 1.13 | 1.18 |
| DMNH 75317 | p. m2 | 1.74 | - | - | 1.23 |
| UCM 67899 | p. m2 | 1.59b | - | - | 1.25 |
| Pontifactor bestiola | |||||
| UCM 71129 | M1 | 1.58 | 1.78 | - | - |
| unnamed apternodontid sp. | |||||
| SDSNH 110348 | p. M1 or 2 | 0.49b | 1.05b | - | - |
| SDSNH 110349 | p. m1 or 2 | 0.79b | 0.63b | - | - |
| unnamed lipotyphlan sp. | |||||
| DMNH 75258 | p4 | 0.80 | - | 0.54 | 0.54 |
| Viverravus gracilis | |||||
| UCM 95809 | M2 | 2.60 | 4.15 | - | - |
TABLE 3. Measurements (in mm) of Hyopsodus sp., Uintatherium anceps, Wickia sp., cf. W. brevirhinus, Triplopus sp., cf. T. obliquidens, Epihippus sp., cf. E. gracilis, and Merycobunodon? walshi new species from TBM. Abbreviations are: ap = greatest anteroposterior length; b = broken dimension; p. = partial; tr = greatest transverse width; tra = anterior transverse (trigonid) width; trp = posterior transverse (talonid) width.
| Taxon/Specimen number | Position | ap | tra | trp |
| Hyopsodus lepidus | ||||
| UCM 67956 | M1 or 2 | 3.92 | 4.97 | 4.67 |
| UCM 67958 | m1 or 2 | 3.71 | 3.05 | 2.99 |
| Uintatherium anceps | ||||
| DMNH 75308 | P3 or 4 | 20.4 | 29.3 | 26.8 |
| DMNH 75310 | p2 | 20.9 | 11.7 | 14.1 |
| DMNH 75309 | m2 | 32.3 | 28.3 | 24.1 |
| Wickia sp., cf. W. brevirhinus | ||||
| DMNH 75312 | I3 | 21.8 | 22.3 | - |
| DMNH 75306 | C | 21.2 | 18.1 | |
| DMNH 75311 | P2 | 20.4 | 19.8 | - |
| DMNH 75305 | M1 | 40.6 | 39.3 | - |
| DMNH 75304 | M3 | 50.8 | 49.1 | - |
| DMNH 75314 | p. p4 | - | - | 27.1 |
| DMNH 75307 | m1 | 47.8 | 28.1 | 28.7 |
| Triplopus sp., cf. T. obliquidens | ||||
| UCM 69053 | p2 | 7.85 | 4.00 | 4.09 |
| p3 | 9.94 | - | - | |
| p4 | 10.55 | 6.52 | 7.38 | |
| m1 | 13.10 | 8.15 | - | |
| DMNH 75320 | p4 | 10.07 | 6.20 | 6.56 |
| p. m2 | - | - | 8.52 | |
| DMNH 75315 | m1 | 13.45 | 6.77 | 7.52 |
| Epihippus sp., cf. E. gracilis | ||||
| SDSNH 110408 | p3 | 7.40 | 4.35 | 4.70 |
| Homacodon sp., cf. H. vagans | ||||
| UCM 95810 | p. p3 | 3.36b | 1.51b | - |
| Merycobunodon? walshi n. sp. | ||||
| UCM 69053 (holotype) | M1 or 2 | 5.98 | 7.71 | 7.19 |
TABLE 4. Comparison of dental characters of M1 or 2 of Merycobunodon? walshi to the M1-2s of other middle Eocene oromeryicids and homacodonts (Mercobunodon littoralis, Protylopus stocki, Protylopus annectans, Protylopus pearsonensis, Oromeryx plicatus, Malaquiferus tourteloti, Helohyus milleri, Antiacodon pygmaeus, Homacodon vagans, Bunomeryx montanus, Hylomeryx annectans, Mytonomeryx scotti, Pentacemylus progressus, Mesomeryx grangeri and Apriculus praeteritus). Shared characters are shown in bold.
| Taxon | Characters | |||||||
| Mesostyle | Hypocone | Protoconule | Post- protocrista bifurcation |
Paracone & metacone ribs |
Enamel crenulation | Selenodonty (crescentic primary cusps) | Crown height | |
| M.? walshi | present moderate | absent | ? | present | present - weak | present -weak | buno-selenodont | low |
| M. littoralis | present moderate | absent | present | present | present - moderate | present moderate | buno-selenodont | low |
| P. stocki | present strong | absent | absent | present | present - strong | present -moderate | moderate | moderate |
| P. annectans | present strong | absent | absent | present | present - strong | present -moderate | moderate | moderate |
| P. pearsonensis | present strong | absent | absent | present | present - strong | present -moderate | moderate | moderate |
| O. plicatus | present strong | absent | absent | present | present - strong | present - heavy | moderate | moderate |
| M. tourteloti | present strong | absent | absent | present | present - very strong | present - heavy | moderate | moderate |
| H. milleri | incipient | present | present | absent | absent | absent | bunodont | low |
| A. pygmaeus | absent | present | present | absent | absent | absent | bunodont | low |
| H. vagans | absent | present | present | absent | absent | absent | bunodont | low |
| B. montanus | present | present | present | absent | present -moderate | absent | moderate | moderate |
| H. annectans | absent to incipient | present | present | absent | incipient | absent | moderate | moderate |
| M. scotti | present strong | present | present | absent | present -strong | absent | moderate | moderate |
| P. progressus | present strong | M1 vestigial M2 absent | present | absent | present -strong | present -moderate | moderate | moderate |
| M. grangeri | absent | absent | present | absent | present -weak | absent | moderate | moderate |
| A praeteritus | absent | absent | present | absent | absent | absent | bunodont | low |
TABLE 5. Taxa 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 holdovers in the TBM and BTC, and taxa that range-through to Ui1b or later. Superscripts in the table indicate the reference numbers. References: 1, Leidy (1872b); 2, Marsh (1872b); 3, Matthew (1909); 4, Troxell (1923a); 5, Wilson (1937); 6, McKenna and Simpson (1959); 7, Wood (1959); 8, Wood (1973); 9, Robinson (1968a); 10, Szalay (1969); 11, Szalay (1976); 12, West (1974); 13, Gazin (1976); 14, Krishtalka (1976b); 15, Lillegraven et al. (1981); 16, West and Hutchinson (1981); 17, Wilson and Schiebout (1984); 18, West (1982); 19, Wilson (1984); 20, Wilson (1986); 21, Krishtalka, personal communication in Wilson (1986); 22, McCarroll et al. (1996); 23, Walsh (1996b); 24, Asher et al. (2002); 25, Turnbull (2002); 26, Williams and Kirk (2008); 27, Gunnell et al. (2008a); 28, Gunnell et al. (2009); 29, Mihlbachler (2008); 30, Murphey and Dunn (2009); 31, Campisano et al. (2014); 32, Kelly and Murphey (2016a); 33, this paper. FAD = first appearance datum. Index species = taxa restricted to Ui1a. N = number of taxa.
