Environmental Controls on the Distribution of Late Paleozoic Bryozoan Colony Morphotypes: An Example From the Permian of Tasmania, Australia

Bryozoans (trepostomes and fenestellids) in the Zechstein Limestone (Wuchiapingian) of the North-Sudetic Basin (SW Poland): palaeoecological implications

“…The high est bryo zoan di ver sity in the stud ied pro files oc curs in bed ded fa cies, where the fauna is dom i nated by large, fan-shaped or fun nel-shaped col o nies of Spinofenestella geinitzi, which in di cate a low en ergy en vi ron ment and mod er ate or slow sed i men ta tion rates (Raczyñski, 1996) typ i cal of off shore or mid-to outer shelf set tings on the Ca1 slope and ba sin floor and soft sub strates (Reid, 2010) Three types of the col ony growth-forms -membrani poriform, reteporiform and vinculariiform -can be dis tin guished among the bryo zoans in the North Sudetic Ba sin. The dom i nant col ony growth-form (reteporiform) in the Grodziec Syncline belongs to the re tic u late fenestellids.…”

“…Trepostome spe cies, which ex hibit an en crust ing growth form (membraniporiform) may indi cate a shal low depth, mod er ate to high wa ter en ergy en vi ronment, with low sed i men ta tion rate (cf. Nel son et al, 1988;Reid, 2010) and oc cur mostly in the mar ginal parts of the SPB, where reefal/biohermal struc tures ex isted dur ing the Ca1 (Leszczyna Syncline). More over, they are also abun dant and di verse in the lower part of the Ca1 in the west ern part of the North Sudetic Ba sin (Lwówek Sl¹ski Syncline) be ing ac com pa nied by the productid of Horridonia horrida and oc cur ring in a low-en ergy and low sed i men ta tion ac cu mu la tion rates if sed i ment in put is low or is trapped on shore.…”

“…4-7), where the fauna is dom i nated by the erect col o nies which reveal the reteporiform growth-form and zoaria are com posed of large fan-shaped or fun nel-shaped col o nies of fenestellids with a max i mum height of 10 cm. The wa ter en ergy or tur bu lence is the pri mary con trol on the bryo zoans oc cur rence (Reid, 2010), there fore, we may as sume that erect-rigid fenestellids pre fer the low en ergy en vi ron ment co-oc cur ring with the productid brachi o pods which are com mon in off shore set ting with the mod er ate or slow sed i men ta tion rate and a soft sub strate on the slope of the Ca1 car bon ate plat form and ba sin floor (see also Reid, 2010). Col o nies of Spinofenestella geinitzi (d'Orbigny) are usu ally heavily cal ci fied and are a com mon el e ment of the Ca1 (Figs.…”

Gradients in seasonality and seawater oxygen isotopic composition along the early Permian Gondwanan coast, SE Australia

“…Commonly associated fossils include the epifaunal bivalve Deltopecten, the spiriferoid brachiopods Trigonotreta and Ingelarella, and fenestellid and trepostome bryozoans; other semi-infaunal and infaunal bivalves, crinoids, gastropods, rugose and tabulate corals, and productoid brachiopods are also variably present (Clapham and James, 2008;Clarke, 1969Clarke, , 1992McClung, 1980a;Reid, 2010;Runnegar, 1969bRunnegar, , 1979Runnegar, , 1980a. These assemblages of organisms are characteristic of open marine shelf conditions and therefore indicate fairly normal marine salinities (Clapham and James, 2008).…”

“…The Darlington Limestone in particular contains numerous layers of dropstones, some of which are very large (Fielding et al, , 2010Isbell et al, 2012;Reid, 2010;Runnegar, 1979). Glendonites are calcite pseudomorphs after the mineral ikaite (CaCO 3 ·6H 2 O), an authigenic hydrated calcium carbonate that forms in sediments at temperatures below ∼4 • C (Bischoff et al, 1993;Marland, 1975;Selleck et al, 2007;Suess et al, 1982) and hence constrains depositional temperatures to near freezing, at least during winters.…”