Scientists at the University of Manchester have discovered what is believed to be the smallest fossil ever found.
A 50-million-year-old parasite - hitching a ride on a not-much-bigger spider - was discovered during a scan of Baltic amber.
Published in the Royal Society's Biology Letters, the find was made using a computed tomography (CT) scan, which builds up a 3-D image from multiple flat scans.
Biologist Dr David Penney wrote in the paper that the arthropod fossil was extremely small - less than two tenths of a millimetre long - and "extremely rare".
Dr Penney wrote that the Faculty of Life Sciences teams would not have been able to identify the mite without the CT scan.
He told the BBC: "CT allowed us to digitally dissect the mite off the spider in order to reveal the important features on the underside required for identification."
"The specimen, which is extremely rare in the fossil record, is potentially the oldest record of the living family Histiostomatidae. "
"Most amber fossils consist of individual insects or several insects together, but without unequivocal demonstrable evidence of direct interaction. "
Fellow biologist Dr Richard Prezoisi added that the team could now date how long species such as the mite had been using larger organisms for transportation.
He said it would give "important clues as to how far back in geological time such behaviours evolved".




据英国《每日邮报》11月11日报道，英国曼彻斯特大学的科学家发现了被认为是迄今为止最小的化石。
这只5000万年前的寄生虫是在科学家扫描一只波罗的海琥珀时发现的，它正附着在一只比它大不了多少的蜘蛛身上。
这一发现发表在了英国皇家学会的《生物学通讯》上，是科学家利用计算机断层扫描技术发现的。该技术能将多个平面断层扫描图像合成一张3D图像。

生物学家大卫-彭尼在论文中写道：这只节肢动物的化石极其微小--还不到五分之一毫米长，并且"极为罕见"。

彭尼博士写道，如果没有计算机断层扫描技术，（曼彻斯特大学）生命科学院的研究小组就不会发现这只螨虫。
他告诉BBC的记者说："计算机断层扫描技术使我们把这只螨虫从蜘蛛身上分离下来，以便展示能识别其身份的身体底部的重要特征。"

"这只螨虫标本在化石记录中极为罕见，它有可能是现存薄口螨科动物家族中最为古老的一种。"
"大多数的琥珀化石内含一只或多只昆虫，但是没有直接的证据证明它们之间存在着直接的相互作用。

他的同事理查德-普雷佐伊斯补充道，现在研究小组可以确定从多久之前象这只螨虫一样的物种就开始利用大型的生物做交通工具。

他说这将为研究"这种行为是在多远古的地质时期逐渐形成的提供重要的线索。"

• spider [´spaidə] n.蜘蛛；三角架 (初中英语单词)
• extremely [ik´stri:mli] ad.极端地；非常地 (初中英语单词)
• faculty [´fækəlti] n.才干；天赋；院，系 (初中英语单词)
• identify [ai´dentifai] vt.认出；鉴定；验明 (初中英语单词)
• manchester [´mæntʃistə] n.曼彻斯特 (高中英语单词)
• specimen [´spesimən] n.标本，样品；抽样 (高中英语单词)
• species [´spi:ʃi:z] n.(生物的)种，类 (高中英语单词)
• fossil [´fɔsəl] n.老顽固 a.化石的 (英语四级单词)
• biology [bai´ɔlədʒi] n.生物学，生态学 (英语四级单词)
• parasite [´pærəsait] n.寄生动(植)物；食客 (英语六级单词)
• baltic [´bɔ:ltik] a.波罗的海的 (英语六级单词)
• geological [dʒiə´lɔdʒikəl] a.地质学的 (英语六级单词)