Calede et al.—Ecomorphology of Leptarctus oregonensis
carnassial/10^(0.5906*Log (body mass)+1.9842))*100. The regression was run in R 3.3.1 (R Development Core Team, 2015) using RStudio 1.0.143 (RStudio, 2015). Although our formulas differ (they are dataset dependent), the BFQs we calculated are very similar to those calculated byWroe et al. (2005). We also investigated the proportions of the teeth of
Leptarctus oregonensis and their possible link with diet by expanding upon a previous analysis by Popowics (2003). We undertook a principal component analysis (PCA) and a cano- nical variate analysis (CVA) of five ratios of tooth measure- ments that describe the shape of the P4 and M1 of small carnivorans.We used the data from Popowics (2003) and newly collected data for extant small carnivores (Table 2) measuring the P4 and M1 following the guidelines of Popowics (2003). The PCA and CVA were run in R 3.3.1 (R Development Core Team, 2015) using RStudio 1.0.143 (RStudio, 2015), the package vegan 2.4-3 (Oksanen et al., 2015), and biostats (McGarigal, 2015). We used a broken-stick distribution to determine the PCA axes whose eigenvalues were larger than expected by chance and only displayed those.
Repositories and institutional abbreviations.—Types, figured, and other specimens examined in this study are deposited in the following institutions: American Museum of Natural History (AMNH), New York City, USA; Frick Collection of the American Museum of NaturalHistory (F:AM),New York City,USA;Natural History Museum of Los Angeles County (LACM), Los Angeles, USA; University of California Museum of Paleontology (UCMP), Berkeley, USA; University of Florida (UF), Gainesville, USA; University of Oregon Museum of Natural and Cultural History (UOMNH), Eugene, USA; University of Washington Burke Museum of Natural History and Culture (UWBM), Seattle, USA.
Systematic paleontology
Nomenclature abbreviations.—P4LB, length of P4; P4W, width of P4; P4PM, length of basin of P4; PRBL, length of shearing blade of P4; M1BL, length of shearing surface of M1; M1LL, length of M1; M1W, width of M1.
Class Mammalia Linnaeus, 1758 Order Carnivora Bowdich, 1821 Family Mustelidae Fischer, 1817 Genus Leptarctus Leidy, 1856
Type species.—Leptarctus primus Leidy, 1856, by original designation
Leptarctus oregonensis Stock, 1930 Figures 1.1–6.1
1924 Leptarctus primus Matthew, p. 139, figs. 37, 38.
1930 Leptarctus oregonensis Stock, Pl. I, fig. 1a, b, text- figures 1, 2.
293
1957 Leptarctus oregonensis; Olsen, p. 2, fig. 2A. 1998 Leptarctus oregonensis; Baskin, p. 158. 2001a Leptarctus primus (part); Lim and Martin, p. 636. 2001 Leptarctus primus (part); Lim, Martin, and Wilson, p. 1044, fig. 1.
2002 Leptarctus primus (part); Lim and Martin, p. 271, fig. 2B.
2005 Leptarctus oregonensis; Baskin, p. 431. 2009 Leptarctus oregonensis; Korth and Baskin, p. 29.
Holotype.—Partial maxilla with the left P4–M1, the right P4, a partial zygomatic arch, and a cranial fragment including part of the lateral temporal crest (LACM (CIT) 206) from LACM CIT 113: exposures of Mascall deposits north of the east fork of the John Day River, ~ 2.4 km NW of Dayville, Oregon (Stock, 1930).
Diagnosis.—Smaller than L. ancipidens, L. mummorum Korth and Baskin, 2009, L. neimenguensis Zhai, 1964, L. primus, L. webbi Baskin, 2005, L. wortmani, and L. kansaensis Lim and Martin, 2001a; rostrum proportionately shorter than in L. wortmani and L. mummorum; skull proportionately narrower, more rectangular in posterior view than that of L. mummorum; postorbital processes not as strong as those of L. mummorum; infraorbital foramen proportionately larger than in L. wortmani; optic foramen directed anterodorsally to the sphenorbital fissure unlike L. mummorum; parasagittal crests do not converge, unlike L. mummorum; post-glenoid foramen larger and located more laterally than in L. mummorum; parietals not as inflated as in L. primus; projections of the tympanic projection do not overlap, unlike in L. primus; tympanic projections present, unlike in L. webbi, and aligned with external auditory meatus, unlike in L. primus; hypocone of P4 smaller than in L. primus and L. ancipidens; metacone blade of P4 longer than in L. primus; tympanic projections do not extend posteriorly to edge of paroccipital process, unlike L. kansaensis; parastyle of P4 not as strong as in L. ancipidens;M1 roughly square, unlike L. ancipidens; no distinct metastyle adjoining the posterior border of the metacone on M1 unlike in L. neimenguensis; tympanic projection double (with a central foramen) unlike L. mummorum, L. wortmani,and L. supremus; paracone of P4 smaller and more acute than in L. desuii and L. martini; meta- cone of P4 longer and more blade-like than in L. desuii and L. martini; parastyle of M1 longer and more-blade like than in L. martini; P4 not wider than long, unlike in L. progressus.
Occurrence.—Early Barstovian of the Mascall Formation of Oregon; early Barstovian of the Olcott Formation of Nebraska.
Description.—UOMNH F-35458 is a nearly complete skull. The rostrum—the only cranial material represented by the type specimen—ismissing, broken anteriorly to P3. The upper canines and incisors are also absent. The P4 and M1 are preserved.
Figure 1. Skull of Leptarctus oregonensis, UOMNH F-35458: (1) dorsal view; (2) ventral view. Abbreviations: aud, auditory bulla; bac, basioccipital; euc, Eustachian canal; fr, frontal; fov, foramen ovale; glsq, glenoid fossa of the squamosal; iof, infraorbital foramen; ju, jugal; lam, lambdoidal crest; mas, mastoid process; max, maxilla; occ, occipital condyles; pal, palatine; par, parietals; poc, paroccipital process; pop, postorbital process; psag, parasagittal crest; pte, pterygoid flange; sq, squamosal; tym, tympanic projections. Scale bar is 1 cm.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175 |
Page 176 |
Page 177 |
Page 178 |
Page 179 |
Page 180 |
Page 181 |
Page 182 |
Page 183 |
Page 184 |
Page 185 |
Page 186 |
Page 187 |
Page 188 |
Page 189 |
Page 190 |
Page 191 |
Page 192 |
Page 193 |
Page 194 |
Page 195 |
Page 196 |
Page 197 |
Page 198 |
Page 199 |
Page 200 |
Page 201 |
Page 202 |
Page 203 |
Page 204
