1002


Journal of Paleontology 91(5):1001–1024


Figure 1. Outcrop belt of Paleocene sediments (light shading). Echinoid fossils (fragmentary in some cases) have been found in counties indicated by dark fill.


a calcareous unit (Tehuacana Limestone, Danian) localized in Falls and Limestone counties, the Paleocene is primarily a siliciclastic unit in central Texas, becoming more calcareous near the border with Mexico (Gardner, 1933). In New Jersey, Paleocene echinoids are known only from


the Vincentown Formation (Cooke, 1959). The age of the Vincentown Formation, based on calcareous nannoplankton, ranges from Zone NP5 to NP9 (Bybell, 1992), or Selandian to Thanetian (Berggren and Pearson, 2005). The calcareous facies of the Vincentown is echinoid-bearing. This facies is bioclastic and composed primarily of bryozoan and other skeletal debris. Echinoid spines are known from the calcareous glauconitic sands of the Aquia Formation (also Thanetian in age) of Virginia and possibly Maryland (Zachos and Levin, 2010). The global Paleocene Series stages (Danian, Selandian, and


Thanetian) are all represented in the Gulf of Mexico Coastal Plain by the Midway group and lower part of the Wilcox Group. The Midway Group comprises predominantly marine deposits. The upper units become progressively more terrigenous in character in the western Gulf of Mexico region, where they are overlapped by the deltaic sands of the Wilcox Group of late Paleocene (Thanetian) and early Eocene (Ypresian) age


(Davidoff and Yancey, 1993). In the eastern Gulf of Mexico region, the Wilcox Group is more commonly represented by marginal-marine deposits. In southwestern Georgia and southern Alabama echinoids are common in the calcareous portions of the Clayton Formation, which ranges from Zone NP1 to NP2 (Danian). The Clayton is characteristically a coarse bioclastic limestone composed of bryozoan, algal, and other skeletal debris in Georgia and eastern Alabama; a fine-grained, somewhat chalky limestone in central Alabama; and a mix of calcareous glauconitic sand, sandy bioclastic limestone, and fine-grained clayey limestone in northern Mississippi and eastern Arkansas. There are some unconfirmed reports of echinoid occurrences in the argillaceous Porters Creek Formation, Zone NP3 to NP4 (Danian–Selandian) (Mancini and Tew, 1991). The echinoid- bearing but isolated and fault-bound Salt Mountain Limestone outcrop in Alabama is correlated with the Nanafalia Formation, Zone NP5 through NP8 (Selandian–Thanetian) and roughly equivalent to the Vincentown Formation. The Salt Mountain Limestone is predominantly a dense, chalky, coralline limestone, coarser near the exposed base where it grades into a bioclastic limestone with algal, foraminiferal, and echinoderm skeletal debris. Disarticulated echinoid plates and spines are ubiquitous


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