744
Journal of Paleontology 89(5):730–747
Table 5. Distribution of bryozoan species from the Upper Triassic of New Caledonia (this paper). Species
Metastenodiscus zealandicus Dyscritellopsis isoseptatus Arcticopora lobatula Arcticopora kobayashii
Age in New Caledonia Norian-Rhaetian
Norian, Warepan Norian-Rhaetian Norian-Rhaetian
The presence of rudites with a dominantly hard-bottom
fauna overlying an unconformity indicates a period of erosion, perhaps even emergence, at the beginning of Otapirian time, and this may be partly coincident with, even part of, the event that sparked the widespread submarine slumping at the end of the Warepan in the Murihiku Terrane (see Grant-Mackie and Lowry, 1964) and which is also apparent in Warepan sequences in New Caledonia in the Téremba Terrane.
Biogeography.—The bryozoan fauna from the Triassic of New Caledonia reveals a mixture of elements showing connections both with the Murihiku and the Torlesse terranes of New Zealand [compare Schäfer and Grant-Mackie, (1994) for the Triassic New Zealand bryozoan fauna], and to the Upper Triassic of Japan (Sakagami, 1972). Whereas Metastenodiscus zealandicus was first described from the lower to middle Norian (Otamitan) Murihiku terrane indicating a Gondwana prove-
nience, Dyscritellopsis isoseptatus and Arcticopora lobatula first described from the Torlesse terrane of New Zealand display a Tethyan provenance (Schäfer and Grant-Mackie, 1994). The same holds for Arcticopora kobayashii first described by Sakagami (1972) from Triassic (lower Carnian) rocks of the Sakawa basin, Shikoku island (Japan) also considered to be of Tethyan character (Table 5). So far, no simple Gondwana con- nection can be stated for the Triassic bryozoans from New Caledonia.
Evolution and Elvis taxa.—On a global scale, Triassic bryozoans are holdovers of various Paleozoic stenolaemate stocks most belonging to the order Trepostomata. Most of the Palaeozoic stenolaemate orders were extinguished during or at the end of the Permian. The exception was the order Trepostomata, which reoccurred in the earliest Triassic and within a time span over 50 million years radiated again to evolve a substantial number of species. The youngest trepostomes are known from the Rhaetian, the group finally being extinguished by the end of the Triassic. An alternative hypothesis, suggested by Boardman (1984), proposes a direct relation between Meso-/Cenozoic Cyclostomata and Paleozoic orders. Bryozoans demonstrate various examples of homeomorphy
(e.g., Voigt and Flor, 1970; Hinds, 1975; Blake, 1980; McKinney et al., 1993; Taylor and Badve, 1995, Ernst et al., 2012). Homeomorphy results from convergent evolution of traits (homoplasy), sometimes through heterochrony (Anstey, 1987). Stenolaemate bryozoans show homeomorphy not only of external characters such as lyra-shaped colonies in fenestrates and cyclostomes (McKinney et al., 1993) but also of internal characters. One of the best studied examples includes the development of four-sided autozooecial chambers in trepostome bryozoans (Boardman and McKinney, 1976), independently
Original age early to middle Norian
late Carnian to early Norian late Carnian to early Norian early Carnian
Location
New Zealand New Zealand New Zealand Japan
developed several times during the Palaeozoic (e.g., Rhombotrypa, Rhombotrypella , Tetratoechus,and Eodyscritella). Certainly, the presence of homeomorphy significantly
compromises stenolaemate bryozoan taxonomy. Indeed, molecular sequence data obtained from Recent cyclostomes has shown numerous skeletal morphological characters (e.g., maculae, diaphragms or hemiphragms, brooding struc- tures) to represent homoplasy (Taylor and Weedon, 2000; Waeschenbach et al., 2009), implying high levels of home- omorphy among stenolaemates. Therefore, a certain caution is required in interpreting morphological characters in bryozoans, especially in taxa distantly positioned in age. Most Triassic trepostomes have been interpreted as belonging to middle to late Palaeozoic families and even genera (notably Paralioclema, Pseudobatostomella, Stenodiscus, Dyscritella), although, more likely, they represent separate genera that have evolved from the late Palaeozoic genera. For most of the Triassic species, a common morphologic character is the development of numer- ous diaphragms both in autozooecia and heterozooecia. This makes them similar to Devonian taxa (e.g., Paralioclema, Pseudobatostomella). However, it seems to be an independent phenomenon for the Triassic genera and species, representing homeomorphy.
Acknowledgments
J.A.G.-M. acknowledges with thanks support from the Sir Charles Fleming Fund, Royal Society of New Zealand, for visiting Kiel, and the hospitality of the Institut für Geowissenschaften, Christian-Albrechts-Universität, Kiel, and its staff during a month’s visit associated with this project. Much assistance with data and information was provided by
Dr. H. J. Campbell, GNS Science, Wellington, who also provided specimens collected with Pierre Maurizot, Bureau de Recherches Géologiques et Minières, Nouméa, New Caledonia. Dr N. Hudson, School of Environment, University of Auckland, assisted in tracking down locality data and
collections.Ms Louise Cotterall, of the same institution, is thanked for the production of the line drawings. Specimen slides and acetate peels were provided by Wolfgang Reimers; photographs by Ute Schuldt.
References
Aitchison, J.C., Ireland, T. R., Clarke, G.L., Cluzel, D., Davis, A.M., and Meffre, S., 1998, Regional implications of U/Pb age constraints on the tectonic evolution of New Caledonia: Tectonophysics, v. 299, p. 333–343.
Anstey, R.L., 1987, Astogeny and phylogeny: evolutionary heterochrony in Paleozoic bryozoans: Paleobiology, v. 13, p. 20–43.
Anstey, R.L., and Perry, T.G., 1970, Biometric procedures in taxonomic studies of Paleozoic bryozoans: Journal of Paleontology, v. 44, p. 383–398.
Avias, J., 1953, Contribution à l’étude stratigraphique et paléontologique des formations antécretacées de la Nouvelle-Calédonie centrale: Sciences de la Terre, v. 1, p. 1–276.
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