近日,，加拿大古生物學(xué)家發(fā)現(xiàn)一種奇怪的生物，正確地說是一種動物,，它卻長得像植物,。但是目前還沒有發(fā)現(xiàn)哪個現(xiàn)代生物與之類似，而這種奇怪的生物可能在史前時期吸引了大多數(shù)撲食性生物的眼球,。該生物存在于五億年前的淺水海底,，科學(xué)家將這種生物描述為具有低矮且密集的特征，當(dāng)這些生物隨海波漂動時,，就如同潛藏在淺海的郁金香,，具有極強(qiáng)的外觀“欺騙”性。
郁金香
科學(xué)家研究發(fā)現(xiàn)這種生物具有球形的“根部”,、每個莖的頂部呈杯狀結(jié)構(gòu),，或者稱為花萼，并有獨(dú)特的濾食系統(tǒng)以及腸道消化系統(tǒng),。值得注意的是,，該動物的排泄孔正好位于頂部,，因此很可能會把它當(dāng)成郁金香而聞一聞。圖為皇家安大略省博物館的古生物學(xué)家在不列顛哥倫比亞省約霍國家公園,、落基山國家公園聯(lián)合國教科文組織世界遺產(chǎn)保護(hù)區(qū),。
史前類“郁金香”生物化石
史前類“郁金香”生物
古生物學(xué)家在不列顛哥倫比亞省約霍國家公園
多倫多大學(xué)的古生物學(xué)家洛娜·奧布賴恩（Lorna O’Brien）認(rèn)為：這樣的進(jìn)食系統(tǒng)在動物界似乎是獨(dú)一無二的，我們還不清楚它與其他生物是否存在進(jìn)化上的關(guān)系,。奧布賴恩與這項(xiàng)研究的負(fù)責(zé)人,，皇家安大略省博物館無脊椎動物古生物部的副教授琴伯納德卡倫（Jean-Bernard Caron）將他們的研究結(jié)果分布在本月的《PLoS ONE》期刊上。
該奇怪的史前生物是科學(xué)家在廣泛研究了1133片化石標(biāo)本后發(fā)現(xiàn)的,，位于加拿大洛基山脈著名的布爾吉斯頁巖,，其具有類似郁金香的形態(tài)特征，正式的官方名稱為Siphusauctum gregarium,。對布爾吉斯頁巖地區(qū)的化石研究結(jié)果表明,，許多原始古生物都與現(xiàn)有的生物種類存在不同程度的聯(lián)系，但是這個類似郁金香的奇怪生物明顯與眾不同,，找不到它的起源以及演化趨勢,。
奧布賴恩和卡倫認(rèn)為這個類郁金香生物是可以過濾水，進(jìn)食水中的顆粒物質(zhì),，并用六個小孔流入“花萼”中,，并通過梳狀結(jié)構(gòu)“捕獲”食物，最后在一個巨大的胃中消化,。由于該生物是集群性的生活習(xí)性,，當(dāng)棲息地被大規(guī)模泥石流掩埋時，形成了目前所發(fā)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.
