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Ernst et al.—New caledonian Triassic bryozoan


Table 2. Descriptive statistics of Dyscritellopsis isoseptatus Schäfer & Grant Mackie, 1994


Parameter


Branch diameter, mm Exozone width, mm Endozone width, mm Aperture width, mm Aperture spacing, mm


Acanthostyle diameter, mm Acanthostyles per aperture Heterozooecia diameter, mm Heterozooecia per aperture


Autozooecial diaphragm spacing, mm 50 0.22 0.066 29.66 0.11 0.41 Exozonal wall thickness, mm


50 0.07 0.024 35.05 0.03 0.12


CV = coefficient of variation; MAX = maximal value; MIN = minimal value; N = number of measurements; SD = sample standard deviation; X = mean.


more abundant heterozooecia and acanthostyles than in intermacular area.


Material.—Otapirian of Ile Hugon: NC/f4 (AU7148), NC/f7 (Au7149d-e), NC/f109 (A7U165(1-7)), Otapirian of Ile Ducos: f50 (AU7194a (228)), NC/f60 (AU7214a), NC/f97 (AU9677-9); NC/f508 (Au 7153), NC/f509 (AU7154), NC/ f555 (AU7218 (252b)), NC/f559 (AU7213); Otapirian of Ile Leprédour: Otapirian of Ilot Turpin: NC/f77 (AU7791); Warepan of Ile Page: NC/f336 (AU7786-6).


Occurrence.—New Zealand; upper Carnian to lower Norian, Oretian. New Caledonia, Ile Page, Ile Leprédour; Upper Triassic, Norian, Warepan. New Caledonia, Ile Ducos, Ile Hugon; Upper Triassic, Rhaetian, Otapirian.


Remarks.—Arcticopora lobatula (Schäfer and Grant-Mackie, 1994) differs from A. christiei Fritz, 1961 from the Lower Triassic of Canada in its larger autozooecial apertures and greater distances between aperture centers (average aperture width 0.16mm vs. 0.11mm in A. christiei; average distances between aperture centers 0.32mm vs. 0.26mm in A. christiei). Arcticopora lobatula differs from A. kobayashii in the greater distances between aperture centers (average distances between aperture centers 0.32mm vs. 0.27mm in A. kobayashii).


Arcticopora kobayashii (Sakagami, 1972) Figures 10.7–10.8, 11.1–11.6; Table 4


1948 Ceriopora sp. Kobayashi, p. 176. 1949 Ceriopora sp. Kobayashi, p. 137.


1972 Pseudobatostomella kobayashii Sakagami, p. 274, pl. 33. figs. 1–6.


1979 Pseudobatostomella kobayashii Sakagami, 1979 – Sakagami and Sakai, p. 83, pl. 13, figs. 3–5.


Holotype.—1001. Department of Geology, Faculty of Educa- tion, Ehime University, Japan.


Description.—Branched and encrusting colonies. In branched colonies, branch diameter 2.9–5.3mm, endozone 1.3–2.5mm wide, exozone 0.8–1.5mm wide. Secondary overgrowths common, individual sheets 0.8–0.9mm thick. Exozone


9 1.76 0.704 40.11 0.85 2.70 9 1.86 0.797 42.95 1.30 3.90 80 0.26 0.041 15.44 0.19 0.37 80 0.41 0.060 14.66 0.29 0.54 80 0.07 0.015 20.84 0.05 0.11 70 4.2 0.939 22.14 2.0 7.0 80 0.08 0.027 32.07 0.03 0.16 70 6.2 1.650 26.55 3.0 10.0


N X SD CV MIN MAX 9 5.37 1.714 31.94 3.60 8.20


741


distinctly separated from endozone. Autozooecia long in endo- zone, polygonal in transverse section. Autozooecial apertures rounded-polygonal. Autozooecial diaphragms usually abundant throughout colonies, straight or slightly curved distally, originating from laminated cingulum of autozooecial walls. Acanthostyles moderate to large, varying in size throughout colony, possessing narrow cores of hyaline material and wide laminated sheaths, originating both in endo-and exozone, four to ten surrounding each autozooecial aperture. Heterozooecia rare, short, with rounded- polygonal apertures, restricted to exozone. Autozooecial walls thin, displaying granularmicrostructure, 0.01- to 0.02-mm thick in endozone; merged, showing distinct convex lamination without visible zooecial boundaries, moderately to strongly thickened, non-beaded, 0.04- to 0.11-mm thick in exozone. Laminated cingulum often developed, with lamination parallel to autozooecial wall surface, 0.005- to 0.030-mm thick. Maculae indistinct, consisting of autozooecia with thickened walls and larger acanthostyles.


Occurrence.—Japan; Upper Triassic, middle Norian. New Caledonia, Ile Hugon, Ile Ducos; Upper Triassic, Rhaetian, Otapirian.


Material.—Otapirian of Ile Hugon: NC/f8 (AU7795(1-2)); Otapirian of Ile Ducos: NC/f120 (AU7180), NC/f503 (AU7147).


Remarks.—Arcticopora kobayashii Sakagami, 1972 differs from A. morbosa (Morozova, 1969) from the Upper Triassic of Pamir in having more abundant heterozooecia and larger acanthostyles (acanthostyle diameter 0.04–0.08mm vs. 0.02– 0.03mm in A. morbosa). Arcticopora kobayashii differs from A. formosum (Morozova, 1969) in having fewer heterozooecia. Arcticopora kobayashii differs from A. lobatula (Schäfer and Grant-Mackie, 1994) in the smaller distances between aperture centers (average distances between aperture centers 0.27mmvs. 0.32mm in A. lobatula).


Discussion


Paleoecology and adaptation.—The bryozoans come from rocks that mostly are fairly coarse volcaniclastics (fine to med- ium conglomerates and breccias) indicating position in the vicinity of an island arc complex. The matrix of the embedding sediment often contains high amounts of rounded particles of igneous rocks and organic remains (Fig. 9.6–7). Most species reveal stout, often massive to cushion-shaped colonies indicating adaptation to a high-energy environment, and even those like Arcticopora lobatula and A. kobayashii with dendroid colony shape may be fairly well adapted to cope with stronger water agitation. The bryozoan fauna is accompanied by quite a rich biota


dominated by brachiopods and bivalves, with fewer corals, cephalopods, gastropods, and echinoderms, and rare marine vertebrates, trace fossils and wood, totaling more than 100 species. This association is dominated by members of the benthic fauna occupying hard bottoms, with a few soft-bottom taxa (Phaenodesmia, Maoritrigonia, Parallelodon, Torastarte, Unionites, Makoiamya, Triaphorus, Kalentera, and perhaps the limids); a small number were nekton or pelagic (Heterastridium,


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