778
Journal of Paleontology 91(4):767–780
from four columns of interambulacral plates to two (Fig. 4). Furthermore, this character seems to have been widespread, as crenulate tubercles are known in Permian archaeocidarids from Timor (Wanner, 1841, fig. 2.1), Pakistan (Waagen, 1985), and Hungary (Mihály, 1980). The discovery of archaeocidarids with crenulate tubercles allows for a better understanding of the probable last common ancestor of the euechinoids and cidaroids. That the innovation of crenulate tubercles likely preceded the evolution of a perignathic girdle and the reduction of interambulacral plating to two columns indicates that the evolution of crenulate tubercles probably preceded the last common ancestor of euechinoids and cidaroids, and thus this last common ancestor likely bore crenulate tubercles. It is, of course, possible that the Archaeocidaridae indet. described herein is a separate lineage of archaeocidarids, which conver- gently evolved crenulate tubercles that are not homologous to those of the miocidarids. The ideal way to test this hypothesis would be through phylogenetic analyses. The material described herein, however, is too incomplete to incorporate into a quantitative phylogenetic analysis as the specimens described herein are composed solely of disarticulated material, with numerous characters that would need to be coded as unknown. Furthermore, these unknown data are not random, given that the taxon’s interambulacral plates and spines are the only morpho- logical features that are preserved. Nonrandom preservation, and subsequent nonrandom missing characters, can introduce systematic bias into the topological placement of taxa in cladograms (Sansom and Wills, 2013). This can be a particularly serious problem with respect to determining the phylogenetic placement of taxa near the crown group–stem group transition, as crown group taxa with many missing characters can appear to be members of the stem group (e.g., Sansom et al., 2010). That the indeterminate archaeocidarid described herein had more than two columns of interambulacral plates indicates it is likely a member of the stem group. We hope, however, to test the hypotheses of character evolution put forth herein in a rigorous phylogenetic context with the discovery of more complete specimens in the future.
Conclusions
The Permian echinoid fauna described here expands upon pre- viously known echinoid diversity in the Permian and sheds light on the Paleozoic divergence of crown group echinoids. This is one of the most diverse faunas of echinoids known from the Permian and indicates that a number of major families, the Archaeocidaridae, Proterocidaridae, and the Miocidaridae, coexisted in reefal environments adjacent to the Delaware Basin. The presence of Eotiaris guadalupensis in reefal environ- ments, similar to those inhabited by the European Eotiaris keyserlingi, may indicate that stem group cidaroids originated and preferentially thrived in these reefal environments. Further- more, the presence of crenulate tubercles on the indeterminate archaeocidarid indicates that crenulate tubercles evolved in archaeocidarids, likely before the reduction in interambulacral columns fromfour to two and the evolution of the first perignathic girdle. Crenulate tuberclesmay thus be plesiomorphicwith respect to the echinoid crown group.
Acknowledgments
This work was funded by National Science Foundation Grant IOS1240626. The authors thank S. Wing, M. Florence, D. Levin, J. Strotman, and K. Hollis at the USNM; A. Molineux at the Texas Memorial Museum, Austin, Texas; J. Cuvelier at the Université Lille; Y. Candela at the National Museums Scotland; and T. Ewin at the Natural History Museum, London, for providing access to specimens and specimen numbers. Furthermore, N. den Ouden provided access to specimens at Naturalis Biodiversity Center, Leiden, and S. Donovan provided the photograph in Figure 2.1. S. Zamora was instrumental in arranging the plates, and his suggestion of a black background improved the clarity of the photos. JRT acknowledges a student grant from the Palaeontological Association, which covered costs for the Progress in Echinoderm Palaeontology meeting in Zaragoza, Spain, from which this volume has been produced. Finally, we thank A. Kroh and L. Zachos, our reviewers, for their instructive comments, which helped to refine the manuscript.
References
Agassiz, L., and Desor, E., 1846, catalogue raisonné des families, des generes et des espéces de la classe des Échinodermes: Annales des Sciences Naturelles, Troisiéme Série, Zoologie, v. 6, p. 305–374.
Babcock, L.C., 1977, Life in the Delaware Basin: The paleoecology of the Lamar Limestone, in Upper Guadalupian Facies, Permian Reef Complex, Guadalupe Mountains, New Mexico and West Texas: Permian Basin Section SEPM Publication 79-18, p. 357–389.
Bather, F.A., 1909, Eocidaris and some species referred to it: Annals and Magazine of Natural History Decade 8, v. 33, p. 43–66.
Bell, M.A., and Lloyd, G.T., 2015, strap: An R package for plotting phylogenies against stratigraphy and assessing their stratigraphic congruence: Palaeontology, v. 58, p. 379–389.
Behnken, F.H., 1975, Leonardian and Guadalupian (Permian) conodont biostratigraphy in western and southwestern United States: Journal of Paleontology, v. 49, p. 284–315.
Boos, M.F., 1929, Stratigraphy and fauna of the Luta Limestone (Permian) of Oklahoma and Kansas: Journal of Paleontology, v. 3, p. 241–253. Butts, S.H., and Briggs, D.E.G., 2011, Silicification through time, in Allison, P.A., and Bottjer, D.J., eds., Taphonomy: Process and Bias Through Time: Dordrecht, Springer, p. 411–434.
Cherns, L., and Wright, V.P., 2000, Missing molluscs as evidence of large-scale, early skeletal aragonite dissolution in a Silurian sea: Geology, v. 28, p. 791–794.
Cherns, L., and Wright, V.P., 2009, Quantifying the impacts of early diagenetic aragonite dissolution on the fossil record: Palaios, v. 24, p. 756–771.
Clapham, M.E., 2015, Ecological consequences of the Guadalupian extinction and its role in the brachiopod-mollusk transition: Paleobiology, v. 42, p. 266–279.
Cooper, A.G., and Grant, R.E., 1972, Permian Brachiopods of West Texas, part I: Smithsonian Contributions to Paleobiology, v. 14, p. 1–231.
de Beer, M., 1990, Distribution patterns of regular sea urchins (Echinodermata: Echinoidea) across the Spermonde Shelf, SW Sulawesi (Indonesia), in de Ridder, C., Dubois, P., and Lahaye, C., eds., Echinoderm Research. Proceedings of the Second European Conference on Echinoderms, Brussels, Belgium, 18–21 September 1989: Rotterdam, A. A. Balkema, p. 165–169.
de Koninck, L., 1863, Description of some fossils from India, discovered by Dr. A. Fleming, of Edinburgh: Quarterly Journal of the Geological Society of London, v. 19, p. 1–19.
de Koninck, L., 1882, Notice sur un échinooïde gigantesque du calcaire carbo- nifére de Belgique: Association francaise pour l’Avancement des Sciences, Compte Rendu de la 10e Session, Alger, p. 514–515.
Desor, E., 1855–1858, Synopsis des échinides fossiles: Paris, Reinwald, 490 p. Döderlein, L., 1887, Die Japanischen Seeigel. I Theil. Familie Cidaridae und Salenidae: Stuttgart, E. Schweizerbartsche Verlagshandlung, 60 p.
Donoghue, P.C.J., 2005, Saving the stem group—a contradiction in terms?: Paleobiology, v. 31, p. 553–558.
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 |
Page 233 |
Page 234 |
Page 235 |
Page 236 |
Page 237 |
Page 238 |
Page 239 |
Page 240 |
Page 241 |
Page 242 |
Page 243 |
Page 244 |
Page 245 |
Page 246 |
Page 247 |
Page 248 |
Page 249 |
Page 250 |
Page 251 |
Page 252 |
Page 253 |
Page 254 |
Page 255 |
Page 256 |
Page 257 |
Page 258 |
Page 259 |
Page 260 |
Page 261 |
Page 262 |
Page 263 |
Page 264 |
Page 265 |
Page 266 |
Page 267 |
Page 268 |
Page 269 |
Page 270 |
Page 271 |
Page 272 |
Page 273 |
Page 274 |
Page 275 |
Page 276 |
Page 277 |
Page 278 |
Page 279 |
Page 280 |
Page 281 |
Page 282 |
Page 283 |
Page 284 |
Page 285 |
Page 286 |
Page 287 |
Page 288
