Few bryozoans have been described from the Cretaceous Western Interior Seaway (WIS), which is consistent with the low diversity of other typically stenohaline groups in this large expanse of relatively shallow marine water. Here we describe a new cheilostome bryozoan, Conopeum flumineum n. sp., based on well-preserved material from the Campanian Judith River Formation of the Upper Missouri River Breaks National Monument in north-central Montana. The new species shows strong morphological similarities with Conopeum seurati, a Recent species that is often categorized as brackish, but which is euryhaline and can also be found in marine and stenohaline environments. The new Campanian bryozoan species was found in a locality also containing fragmentary remains of dinosaurs and other terrestrial vertebrates, as well freshwater mollusks and terrestrial plant debris. The sedimentology and facies associations of the fossil-bearing site suggest that the depositional setting was a swamp or tidally influenced fluvial backwater on the Judith River coastal plain. The proximity of the site to the western shoreline of the WIS presumably made it susceptible to occasional marine flooding during storms or extreme tides. Previous occurrences of Conopeum in the Cretaceous of the Western Interior have also been associated with dinosaur remains, corroborating the very nearshore and at times even ‘upstream’ distribution of this euryhaline genus.UUID: http://zoobank.org/bb1fdc8a-5017-44c5-9251-9e24ef3995e3.

中文翻译：

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来自蒙大拿州上白垩纪（坎帕阶）朱迪思河组恐龙遗址的一种新的口吻苔藓虫

从白垩纪西部内陆航道（WIS）中描述的苔藓虫很少，这与这片相对较浅的海水中其他典型的狭盐类群的低多样性是一致的。在这里，我们描述了一种新的 cheilostome 苔藓虫，油菜n. sp.，基于来自蒙大拿州中北部上密苏里河断裂国家纪念碑的坎帕尼亚朱迪思河组保存完好的材料。新物种表现出强烈的形态相似性柞蚕，一种新近出现的物种，通常被归类为半咸水，但它是广盐碱，也可以在海洋和窄盐碱环境中找到。新的坎帕尼亚苔藓虫物种是在一个还包含恐龙和其他陆生脊椎动物的残骸，以及淡水软体动物和陆生植物残骸的地方发现的。含化石地点的沉积学和相组合表明，沉积环境是朱迪思河沿岸平原上的沼泽或受潮汐影响的河流回水。该地点靠近 WIS 的西部海岸线，可能使其在风暴或极端潮汐期间容易受到偶尔的海洋洪水的影响。以前出现的康诺普在西部内陆的白垩纪也与恐龙遗骸有关，证实了这种广盐属的近岸，有时甚至是“上游”分布。UUID：http://zoobank.org/bb1fdc8a-5017-44c5-9251-9e24ef3995e3.