Hendricks—Miocene Conidae from the Gatun Formation of Panama
reported C. spurius from the middle Gatun Formation of Panama on the basis of a single specimen (USNM 645738, Fig. 13.1, 13.2), but its identification is in question (see below). Numerous specimens found at UF locality YN020 confirm the presence of the species in the lower Gatun Formation. Other occurrence records reported by Woodring (1970) from the Neogene of Panama, Costa Rica, Colombia, and Jamaica (Bowden Formation) require confirmation.
Description.—Note that this description pertains only to speci- mens from UF locality YN020, not recent or fossil specimens of C. spurius from elsewhere. Maximum shell size: medium. Typical shell size of specimens from UF locality YN020: medium (36.7mm; N=120). Largest observed specimen from YN020 (UF 271016) has SL 53.5mm. Last whorl.—Shape usually conical, sometimes broadly
conical, rarely ventricosely conical or broadly and ventricosely conical (RD 0.60–0.74, x=0:67; PMD 0.84–0.93, x=0:89; N=47); outline convex on posterior half, slightly concave to straight on anterior half, resulting in a slightly sigmoidal to slightly convex profile. Shoulder carinate and forming a posterior-pointing ridge. Widest part of shell below shoulder. Aperture slightly wider at base than shoulder. Siphonal notch absent. Spiral threads on anterior half, sometimes extending past midline, but rarely extending to shoulder. Spire whorls.—Spire low to high (RSH 0.06–0.25;
x=0:14; N=47); outline concave to slightly sigmoidal. Early spire whorls sometimes stepped, with angulate to subangulate shoulders. In some low-spired specimens (Fig. 13.8, 13.19), the later whorls rise slightly above those that formed earlier, giving the spire a sunken appearance. Quality of preservation prevents the number of protoconch whorls from being determined with confidence, but UF 259766 (Fig. 13.9) appears to show more than two whorls. Similarly, quality of preservation prevents definitive characterization of the features of the earliest whorls, but UF 259756 and UF 259766 suggest that at least one post- nuclear whorl may bear fine tubercles. Sutural ramp often convex on early whorls, often concave on later whorls. Spiral ornamentation on the sutural ramp is highly variable: specimens often have 2–4 fine spiral grooves and/or threads on earlier whorls, but these usually become obsolete later in growth and most mature specimens lack spiral ornamentation on the terminal portion of the ramp (e.g., UF 259746). Subsutural flexure asymmetrical (ASSF 0.2–0.7, x=0:5, N=4), depth approximately twice width (DWSSF 1.7–2.2, x=1:8, N=4).
Coloration pattern.—One pattern present. Pattern consists
of 9–18 rows of spiral elements. The most conspicuous elements on most specimens are large rectangular or sub-rectangular blotches, although these are sometimes irregular in shape, including on the same specimen (Fig. 13.11); these rows are
831
sometimes separated by one or more rows of small dots or dashes. In some specimens, the spiral elements merge at their margins (Fig. 13.14), sometimes producing axial streaks (Fig. 13.15, 13.16). In other specimens, the rectangular blotches are closely spaced (Fig. 13.17) and sometimes connect to form nearly continuous (Fig. 13.18) or continuous (Fig. 13.19) spiral bands. In one observed specimen (Fig. 13.20), spiral elements on the posterior third of the last whorl form markings that are nearly triangular in shape. Sutural ramp with irregularly shaped radial botches that sometimes extend over the shoulder onto the last whorl.
Materials.—USNM 645738 (one specimen, figured by Woodring, 1970; Fig. 13.1, 13.2) and an additional 304 observed specimens, all from UF locality YN020.
shell coloration patterns (e.g., Tucker, 2013, figs. 41–43; Kohn, 2014, pls. 97–100), which is also observed in the specimens from UF locality YN020. Some specimens (e.g., Fig. 13.3–13.8) from YN020 show patterns that are typical of many extant C. spurius, featuring irregularly shaped spiral blotches. More commonly, however, specimens from YN020 have spiral blotches that are nearly rectangular in shape (e.g., Fig. 13.13), although some specimens (e.g., Fig. 13.11) exhibit both irregular and rectangular blotches. In some specimens (e.g., Fig. 13.15, 13.16), spiral rows of blotches coalesce to form axial streaks, while in others (e.g., Fig. 13.17–13.19) they merge to form continuous or nearly continuous spiral bands; these variations of pigmentation patterning are also observed in some extant C. spurius (see Kohn, 2014, pls. 97–100). In his description of Conus molis Brown and Pilsbry, 1911,
Remarks.—Woodring’s (1970, p. 348) assertion that the extant western Atlantic species Conus spurius occurs in the Gatun Formation was based on a single specimen (USNM 645738; Fig. 13.1, 13.2) found at his locality 155, “Middle part of Gatun formation, eastern area.” The >300 specimens found at UF locality YN020—the most of any species—provide substantial additional support for this occurrence in the Gatun Formation of Panama, although USNM 645738 presents addi- tional questions (see below). Extant C. spurius have highly variable, but also distinctive,
Woodring (1970, p. 350) mentioned “immature shells” with a coloration pattern “consisting of spiral rows of brownish crude rectangles, much like the pattern of Conus spurius.” As shown above, the coloration pattern of C. molis is very different from that of C. spurius andthe shells to whichWoodringreferredare assumed to represent specimens of C. spurius. Indeed, Pitt and Pitt (1993) used UV photography to characterize the coloration pattern of a specimen (apparently one of many in their collection) of Conus cf. molis that has a “pattern of spiral rows of crude rectangles, much like the color pattern of C. spurius” (Pitt and Pitt, 1993,
Figure 13. Conus (Spuriconus) spurius Gmelin, 1791 from the Gatun Formation of Panama: (1, 2) photographed under regular light; (3–20) photographed under UV light; all specimens are from UF locality YN020 unless otherwise indicated. (1, 2) USNM 645738, specimen figured by Woodring (1970, pl. 55, fig. 7), Panama Canal Zone, Woodring locality 155, middle Gatun Formation, SL 45.8mm, MD 28.9mm; (3, 4) UF 256537, SL 43.2mm, MD 23.7mm; (5)UF 271003, SL 42.6mm; (6) UF 271004, SL 33.9mm; (7) UF 259760, SL 35.6mm; (8) UF 259745, SL 36.5mm; (9) UF 259766, SL 19.9mm; (10) UF 271005, SL 39.3mm; (11) UF 271006, SL 40.0mm; (12) UF 271007, SL 36.5mm; (13) UF 271008, SL 31.7mm; (14) UF 271009, SL 37.2mm; (15) UF 271010, SL 27.7mm; (16) UF 271011, SL 35.7mm; (17) UF 271012, SL 43.8mm; (18) UF 271013, SL 42.5mm; (19) UF 271014, SL 46.4mm; (20) UF 271015, SL 46.6mm. Scale bar to the left of (1) equals 10mm and pertains to all specimens.
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 |
Page 205 |
Page 206 |
Page 207
