An unusual Pocillopora reef from the Late Miocene of Hispaniola
An unusual Pocillopora reef from the Late Miocene of Hispaniola
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伊斯帕尼奥拉岛晚中新世罕见的波西洛波拉珊瑚礁
DOI：
10.1007/s00338-011-0728-4
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发表时间：
2011
期刊：
影响因子：
3.5
通讯作者：
Böcker
中科院分区：
文献类型：
--
作者：
Reuter;Brachert;Böcker
Pocilloppora是现今印度洋、红海和太平洋的一种常见珊瑚礁，其形态变化范围很广，受环境控制，从次块状到类圆形的直立分枝菌落形式（贝隆，2000年）。在此，我们报告了多米尼加共和国Cibao盆地的Messinian Cercado组中已灭绝的造礁P. cruciamosa（N 19 29′ 07.55 ″，W 071 14′ 47.78 ″; Maier等2007），具有不寻常的健壮分枝生长形态和水平排列的生活方式，这两种形态都没有报道为最近的Pocillopora。其中许多似乎是水平的，嵌入生物碎屑粉质泥灰岩中（图1a），形成5米厚、100米长的堆积物，与由直立、细分支的滨珊瑚和柱珊瑚以及板状伞菌组成的原位珊瑚丛交错（图1 B）。单个Pocilloppora菌落可达近2米长，由10厘米厚的分枝组成（图1a）。这些树枝的下表面光滑，而上表面则呈球根状生长，并被宽间距的疣覆盖（图1c）。在横截面中，生长增量揭示了指向纹理侧的不对称周向生长（图1d）。未观察到再生长模式，如生长方向和/或形状的变化。这表明水平放置的树枝已经就位，暗示着一种爬行的生活方式。因此，生物侵蚀优先出现在珊瑚的上侧（图1d）。
Pocillopora, a common reef coral in the present-day Indian Ocean, Red Sea, and Pacific Ocean, exhibits a wide range of environmentally controlled morphologic variation from submassive to bush-like uprightbranching colony forms (Veron 2000). Herein, we report on extinct reef-building P. crassoramosa from the Messinian Cercado Formation of the Cibao Basin in the Dominican Republic (N 19 29′ 07.55 ″, W 071 14′ 47.78 ″; Maier et al. 2007) that has an unusual robust-branching growth morphology and horizontally disposed lifestyle—both not reported for recent Pocillopora.Large branches of P. crassoramosa, many of which appear to be lying horizontally, are embedded in bioclastic silty marl (Fig. 1 a) and form a 5-m-thick and 100-m-long buildup, which interfingers with an in situ coral thicket composed of upright standing, thin-branched Porites and Stylophora as well as plate-like agariciids (Fig. 1 b). Single Pocillopora colonies reach nearly 2-m-length and consist of up to 10-cm-thick branches (Fig. 1 a). The undersurface of these branches is smooth while the upper surface exhibits bulbous outgrowths and is covered by wide-spaced verrucae (Fig. 1 c). In cross-sections, the growth increments reveal asymmetric circumferential growth that is directed toward the textured side (Fig. 1 d). Regrowth patterns such as changes in growth direction and/or shape are not observed. This indicates the horizontally lying branches are in place and implies a creeping mode of life. Accordingly, bioerosion was found preferentially on the upper sides of the corals (Fig. 1 d).