Journal of Paleontology, 92(4), 2018, p. 577–595 Copyright © 2018, The Paleontological Society 0022-3360/18/0088-0906 doi: 10.1017/jpa.2017.146
Bryozoan fauna of the Lake Valley Formation (Mississippian), New Mexico
Andrej Ernst,1 Karl Krainer,2 and Spencer G. Lucas3 1Institut für Geologie, Universität Hamburg, Bundesstrasse 55, D-20146 Hamburg, Germany ⟨
Andrej.Ernst@
uni-hamburg.de⟩ 2Institute of Geology, Innsbruck University, Innrain 52, A-6020 Innsbruck, Austria ⟨
karl.krainer@
uibk.ac.at⟩ 3New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, New Mexico 87104, USA
⟨
spencer.lucas@
state.nm.us⟩
Abstract.—Ten bryozoan species are described from the Andrecito and Tierra Blanca members of the Lake Valley Formation (Mississippian) of Sierra County, New Mexico, USA. One genus, with one species, is new—a cystoporate, Cystomeson sierraensis n. gen. n. sp. The bryozoans indicate quieter and deeper conditions in the Andrecito Member and more agitated and shallower conditions in the Tierra Blanca Member. The species identified in this study are endemic to North America, whereas at the generic level, the composition is rather cosmopolitan.
UUID:
http://zoobank.org/fc354A60-1fbc-4e41-8b9b-bbfd65e59a71 Introduction
Mississippian rocks were discovered in 1881 at Lake Valley in southern New Mexico (Lucas, 2012) by the famous herpetolo- gist and vertebrate paleontologist Edward Drinker Cope (1840– 1897). Cope also named the Lake Valley Formation for most of the Mississippian strata at Lake Valley. Since Cope’s discovery, much has been written about the phenomenal fossil record of the Lake Valley Formation (Limestone) at its type section (see Kues, 1986 for a review). This fossil record is dominated by exceptionally well-preserved crinoids but also includes diverse coelenterates, brachiopods, and mollusks. One of the less well- studied groups in the Lake Valley Formation fossil assemblages is the bryozoans. Here, we report on material of Lake Valley Formation bryozoans from the collections made by Krainer and Lucas (2012) and discuss their stratigraphic, paleogeographic, and paleoecological significance. These bryozoans include a new genus and a new species named here.
Previous reports of Lake Valley Bryozoa
Taxonomic work on bryozoans was widely neglected in previous geological reports on the Lake Valley Formation. The few existing records bear numerous taxonomic and nomencla- tural biases that need urgent clarification. The only bryozoan species previously described and depicted from the Lake Valley Formation is Trematopora americana established by Miller (1881, p. 312). The description of this species is superficial, but accompanied by few measurements and two illustrations, in natural size and slightly magnified. The genus Trematopora Hall, 1852 belongs to the order Trepostomata. However, Mill- er’s description of T. americana implies the presence of lunaria (“The apertures are margined by a projecting lip which some- times overshadows the lower part of the opening”; Miller, 1881, p. 312), and a hollow, ramose, branched colony. Therefore, this
species must belong to the order Cystoporata. Indeed, Darton (1928, p. 17) listed the species as Fistulipora americana (identified by G. H. Girty) in his list of fossils from this forma- tion. So, Girty (in Darton, 1928) was apparently the first to place this species in Fistulipora M’Coy, 1849. McKee and Gutschick (1969, p. 359) mentioned the species, as Cheilotrypa americana, from the Mississippian Redwall Limestone of Utah. It is not clear, however, who placed this species in the cystoporate genus Cheilotrypa Ulrich, 1884. The precise taxonomic assignment of this species is impossible because its internal morphology is unknown. Kues (1986, p. 212) listed Fistulipora americana in a list of
fossils fromthe Lake Valley Formation.He noted that the species Trematopora americana and T. vesiculosa (apparently the species of Winchell, 1864) are synonymous with F.
americana.The species Trematopora? vesiculosa and T.? fragilis were described by Winchell (1864, p. 3) from the Burlington Limestone (Osagean) of Iowa. Unfortunately, these species were not illustrated byWinchell. Trematopora? vesiculosa could belong to Cystoporata, becauseWinchell (1864, p. 3)mentioned a vesicular skeleton and branched colony without a solid axis (hollow ramose?). In contrast, T.? fragilis could be a branched trepostome. Besides these species (Fistulipora americana, Tremato-
pora americana, and T. vesiculosa), Kues (1986, p. 212) listed the following bryozoans from the Lake Valley Formation: Cheilotrypa sp., Cystodictya aff. C. pustulosa Ulrich, 1890, Cystodictya? sp., Fenestella sp., Hernodia sp. (not a bryozoan), Leioclema (= Lioclema) sp., Lichenotrypa sp., Penniretepora (=Pinnatopora) sp., Polypora sp., Ptylopora sp., Rhombopora sp., and Thamniscus sp. The genus Lichenotrypa Ulrich, 1886 is restricted to the Middle Devonian, whereas others represent typical genera occurring in the Mississippian elsewhere. How- ever, the exact taxonomic assignment of these bryozoans cannot be verified because of the lack of descriptions, illustrations, and identifiable voucher specimens.
577
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 |
Page 208 |
Page 209 |
Page 210 |
Page 211 |
Page 212 |
Page 213 |
Page 214 |
Page 215 |
Page 216 |
Page 217 |
Page 218 |
Page 219 |
Page 220 |
Page 221 |
Page 222 |
Page 223 |
Page 224 |
Page 225 |
Page 226 |
Page 227 |
Page 228 |
Page 229 |
Page 230 |
Page 231 |
Page 232
