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三叶虫,冷面杀手

Trilobites Were Stone-Cold Killers

三叶虫,冷面杀手

by Stephanie Pappas, Live Science Contributor | February 11, 2016 07:07am ET


Trilobites were savvy killers who hunted down their prey and used their many legs to wrestle them into submission, newly discovered fossils suggest.

新发现的化石表明,三叶虫是有头脑的猎手,它们追捕猎物,然后用一对对足肢制服猎物。

The fossils come from a site in southeastern Missouri, not far from the city of Desloge. They are trace fossils, which means they preserve not the organisms themselves, but their burrows. The burrows were made by various species of trilobite as well as by unknown, wormlike creatures.

这些化石来自密苏里州东南部,小城德斯洛各附近。它们属于遗迹化石,也就是说,它们并不是保有生物体本身的样子,而是它们的洞穴。这些洞穴由不同种类的三叶虫-以及未知的类似蠕虫的生物—所造成,

A statistical analysis of these burrows and their intersections shows that they cross one another more than expected, a sign that the trilobites were deliberately hunting down their wormy prey. In a subset of those cases, the trilobites seemed to sidle up to the burrows in parallel, perhaps so they could latch onto the worms lengthwise with their row of legs.

对这些痕迹以及它们之间交叉点的统计分析表明,它们之间的交叉次数远超预期,这是三叶虫有意识地追捕蠕虫状猎物的迹象。在其中的某一类案例中,三叶虫似乎从平行方向悄悄地贴近了这些洞穴,也许这样它们就能沿着蠕虫身体的纵向,用自己的两列足肢抓住它。

"This is legitimately the moment of interaction between the trilobite and the animal that it ate," said study researcher James Schiffbauer, a paleobiologist at the University of Missouri.

“在三叶虫和被它所吃的动物之间,这是一种合乎情理的互动情景。”课题研究者,密苏里大学的古生物学家詹姆斯 斯科菲布尔说。


Trilobite tracks

三叶虫,爬爬爬

The discovery of these fossils came about by accident. During a department field trip to visit a local lead mine, the researchers made a side trip to a known fossil spot. While there, study co-author John Huntley, also a professor at the University of Missouri, stumbled across a block of fossilized burrows, frozen in silty shale. The sediment was set down during the Cambrian period, between 540 million and 485 million years ago, when the area was a shallow nearshore environment. The shallow bottom was likely covered with a dense microbial mat, which made for a rich food source for wormy (or "vermiform") creatures. These worms were, in turn, prey for trilobites.

这些化石的发现实属意外。在系里组织的一次对当地铅矿的田野考察中,研究人员对一个已知的化石点顺便进行了一次考察。就在那儿,论文的共同作者,约翰 亨特利,他也是密苏里大学的一位教授,偶然发现了一块保存在粉质砂岩中的痕迹化石。这种沉积岩形成于寒武纪,距今约5.4亿年至4.85亿年,当时这一地区还是一片浅滩。浅滩底部可能覆盖着密集的微生物群落,为蠕虫类(或蠕虫状)生物提供了丰富的食料。另一方面,这些蠕虫又成了三叶虫的猎物。

"It became sort of a small shallow-water hunting ground for the trilobites," Schiffbauer told Live Science.

“这里成了三叶虫的小型浅水猎场。”斯科菲布尔告诉生活科技杂志说。

Graduate student Tara Selly took on the painstaking task of cataloguing and counting the burrows and their intersections. Her findings revealed that the worm and trilobite tunnels intersected about 30 percent of the time — more than would be expected based on chance alone.

毕业生塔拉 塞利承担这份艰苦的工作,对痕迹及其交叉点进行编号和统计。她的发现揭示出蠕虫洞穴和三叶虫洞穴交叉的次数超过30%—远远超过按随机发生交叉的预期数。

"Likely one-third of [the burrows] were actually capturing predatory events," Selly told Live Science.

“可能有三分之一的洞穴实际上是捕猎活动,”塞利说。


A moment in time

那一瞬间

The trilobites known from this area belong to species with particularly large eyes, Schiffbauer said. Those eyes may have made them adept hunters, he said, able to seek out burrow entrances or impressions. The critters would then burrow down to grasp their prey.

这一地区已知的三叶虫都属于那些眼睛特别大的种类,斯科菲布尔说。这种眼睛使它们成为精明的猎手,他说,能够寻找洞穴的入口或者蛛丝马迹。然后,这些小动物就会打洞下去,抓住它们的猎物。

"What we're seeing is really sophisticated behavior fairly early on in what some people would say is a very simple creature," Schiffbauer said. The trilobites might also have used scent to sniff out their prey, he said.

“我们现在看到的,真的是一种复杂的行为,早先人们都说这是一种非常简单的生物,”斯科菲布尔说。三叶虫可能也会使用嗅学来搜寻猎物,他说。

Predation is important to understand, Huntley told Live Science, but it can be hard to see in the fossil record. Some Cambrian fossils have recorded animals inside the gut tracts of other animals, but it's not clear whether they were hunted and eaten or scavenged. Other signs of predation in the fossil record are wounds or drill holes in skeletons or shells, Huntley said.

捕猎行为对于了解动物十分重要,亨特利说,但是这很难在化石记录中看到。一些寒武纪化石中记录了一些动物在其他动物的消化道内,但是无法弄清它们是被猎捕并吃掉还是食腐行为。另一些在化石记录中的捕食迹象是在骨骼或贝壳上的伤口或者钻孔,亨特利说。

"In this case, what we're getting is actually impressions of the body," Huntley said. "It's a different window into this process that we know is important ecologically and really important evolutionarily as well."

“在这个案例中,我们得到了生物体的确实痕迹,”亨特利说,“这是一个与众不同的窗口,”

The research iss detailed online in the Feb. 15 issue of the journal



http://www.livescience.com/53682-trilobites-were-savvy-killers.html

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  • 1楼
    2016-02-14 00:51 有人 只看Ta

    It's a different window into this process that we know is important ecologically and really important evolutionarily as well."


    理解不能,求赐教。

    [0] |
  • 3楼
    2016-02-14 09:01 773933442 只看Ta

    我们都知道这一行为(据上文推断应指捕食的行为)对于(三叶虫的)生态和进化是非常重要的,而这(据上文推断应指新发现的化石)是一个全新的了解这一行为的窗口。

    [0] |
  • 4楼
    2016-02-14 09:18 trilobite-cc 古生物学与地层学博士生 只看Ta

    楼上已经把意思基本都翻译出来了,这一过程指的应该是通过遗迹化石所反映出来的三叶虫的捕食行为。有一部分三叶虫是捕食者,虽然我们很难发现三叶虫捕食的直接证据,但可以通过一些间接证据来探讨它们的捕食方式和捕食对象。

    [0] |
  • 5楼
    2016-02-14 11:08 有人 只看Ta
    引用@773933442 的话:我们都知道这一行为(据上文推断应指捕食的行为)对于(三叶虫的)生态和进化是非常重要的,而这(据上文推断应指新发现的化石)是一个全新的了解这一行为的窗口。


    谢谢。

    [0] |

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