近日，科学家们发现了一种生活在史前时代，体型较之现代蚂蚁如同“怪兽”般，身长超过5厘米的大蚂蚁化石。

据国外媒体报道，科学家们将这种蚂蚁命名为“Titanomyrma lubei”，生活在距今约5千万年前，大小差不多相当于现代蜂鸟。这种生物的化石被发现在美国怀俄明州，成为迄今为止所发现的最大蚁类物种之一。

这种体型巨大的蚂蚁生活在炎热气候的地区，与之前曾在怀特岛和德国发现的蚁类来自同一时期，并且非常相似。5千万年前的始新世时期(Eocene period)，当时极地温度要高于现今，并且各大陆版块间彼此距离较近。据此研究人员推断这些蚂蚁当时可能在以上几个地区之间生活或者“迁徙”。

西蒙弗雷泽大学的布鲁斯·阿奇博尔德(Bruce Archibald)博士表示，这一发现令人印象深刻，除了体型巨大外在化石上还发现有翅膀的痕迹，但几乎没有其它信息能用来分析其如何生活的情况。研究人员们根据其分布区域，估计这种巨蚁或许是当时在欧洲和北美之间长途跋涉。

原文出处：

Proc. R. Soc. B  doi: 10.1098/rspb.2011.0729

Intercontinental dispersal of giant thermophilic ants across the Arctic during early Eocene hyperthermals

S. Bruce Archibald1,2,3,*, Kirk R. Johnson4, Rolf W. Mathewes1 and David R. Greenwood5

Abstract

Early Eocene land bridges allowed numerous plant and animal species to cross between Europe and North America via the Arctic. While many species suited to prevailing cool Arctic climates would have been able to cross throughout much of this period, others would have found dispersal opportunities only during limited intervals when their requirements for higher temperatures were met. Here, we present Titanomyrma lubei gen. et sp. nov. from Wyoming, USA, a new giant (greater than 5 cm long) formiciine ant from the early Eocene (approx. 49.5 Ma) Green River Formation. We show that the extinct ant subfamily Formiciinae is only known from localities with an estimated mean annual temperature of about 20°C or greater, consistent with the tropical ranges of almost all of the largest living ant species. This is, to our knowledge, the first known formiciine of gigantic size in the Western Hemisphere and the first reported cross-Arctic dispersal by a thermophilic insect group. This implies intercontinental migration during one or more brief high-temperature episodes (hyperthermals) sometime between the latest Palaeocene establishment of intercontinental land connections and the presence of giant formiciines in Europe and North America by the early middle Eocene.