近日，加拿大古生物学家发现一种奇怪的生物，正确地说是一种动物，它却长得像植物。但是目前还没有发现哪个现代生物与之类似，而这种奇怪的生物可能在史前时期吸引了大多数扑食性生物的眼球。该生物存在于五亿年前的浅水海底，科学家将这种生物描述为具有低矮且密集的特征，当这些生物随海波漂动时，就如同潜藏在浅海的郁金香，具有极强的外观“欺骗”性。
郁金香
科学家研究发现这种生物具有球形的“根部”、每个茎的顶部呈杯状结构，或者称为花萼，并有独特的滤食系统以及肠道消化系统。值得注意的是，该动物的排泄孔正好位于顶部，因此很可能会把它当成郁金香而闻一闻。图为皇家安大略省博物馆的古生物学家在不列颠哥伦比亚省约霍国家公园、落基山国家公园联合国教科文组织世界遗产保护区。
史前类“郁金香”生物化石
史前类“郁金香”生物
古生物学家在不列颠哥伦比亚省约霍国家公园
多伦多大学的古生物学家洛娜·奥布赖恩（Lorna O’Brien）认为：这样的进食系统在动物界似乎是独一无二的，我们还不清楚它与其他生物是否存在进化上的关系。奥布赖恩与这项研究的负责人，皇家安大略省博物馆无脊椎动物古生物部的副教授琴伯纳德卡伦（Jean-Bernard Caron）将他们的研究结果分布在本月的《PLoS ONE》期刊上。
该奇怪的史前生物是科学家在广泛研究了1133片化石标本后发现的，位于加拿大洛基山脉著名的布尔吉斯页岩，其具有类似郁金香的形态特征，正式的官方名称为Siphusauctum gregarium。对布尔吉斯页岩地区的化石研究结果表明，许多原始古生物都与现有的生物种类存在不同程度的联系，但是这个类似郁金香的奇怪生物明显与众不同，找不到它的起源以及演化趋势。
奥布赖恩和卡伦认为这个类郁金香生物是可以过滤水，进食水中的颗粒物质，并用六个小孔流入“花萼”中，并通过梳状结构“捕获”食物，最后在一个巨大的胃中消化。由于该生物是集群性的生活习性，当栖息地被大规模泥石流掩埋时，形成了目前所发生的化石。(生物谷 Bioon.com)
doi:10.1371/journal.pone.0029233
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A New Stalked Filter-Feeder from the Middle Cambrian Burgess Shale, British Columbia, Canada
Lorna J. O'Brien, Jean-Bernard Caron
Burgess Shale-type deposits provide invaluable insights into the early evolution of body plans and the ecological structure of Cambrian communities, but a number of species, continue to defy phylogenetic interpretations. Here we extend this list to include a new soft-bodied animal, Siphusauctum gregarium n. gen. and n. sp., from the Tulip Beds (Campsite Cliff Shale Member, Burgess Shale Formation) of Mount Stephen (Yoho National Park, British Columbia). With 1,133 specimens collected, S. gregarium is clearly the most abundant animal from this locality.
This stalked animal (reaching at least 20 cm in length), has a large ovoid calyx connected to a narrow bilayered stem and a small flattened or bulb-like holdfast. The calyx is enclosed by a flexible sheath with six small openings at the base, and a central terminal anus near the top encircled by indistinct openings. A prominent organ, represented by six radially symmetrical segments with comb-like elements, surrounds an internal body cavity with a large stomach, conical median gut and straight intestine. Siphusauctum gregarium was probably an active filter-feeder, with water passing through the calyx openings, capturing food particles with its comb-like elements. It often occurs in large assemblages on single bedding planes suggesting a gregarious lifestyle, with the animal living in high tier clusters. These were probably buried en masse more or less in-situ by rapid mud flow events.
Siphusauctum gregarium resembles Dinomischus, another Cambrian enigmatic stalked animal. Principal points of comparison include a long stem with a calyx containing a visceral mass and bract-like elements, and a similar lifestyle albeit occupying different tiering levels. The presence in both animals of a digestive tract with a potential stomach and anus suggest a grade of organization within bilaterians, but relationships with extant phyla are not straightforward. Thus, the broader affinities of S. gregarium remain largely unconstrained.
