科学家对在南澳大利亚袋鼠岛发现的已有5.15亿年历史的化石“复眼”进行分析,发现它们拥有3000多个独立单眼,因此它们的视力比当时其他所有动物都更好
这些化石复眼观察这个世界的像素超过3000,因此它们的拥有者在当时具有很大的视觉优势,因为同一时期的其他动物的像素大约只有100,看到的一切都非常模糊(左)。但它无法与现有蜻蜓的视力相比,因为后者拥有最棒的复眼,它的像素是2.8万(右)
这是现有昆虫——食肉动物食虫虻的复眼,它展示的是构成复眼的独立单眼
最近考古学家在南澳大利亚袋鼠岛挖掘出已有5.15亿年历史的化石“复眼”,它们像一只刚刚被拍扁的苍蝇的眼睛,包含超过3000个可独立成像的单眼。据对其进行分析的澳大利亚科学家称,这些原始史前动物的视力非常棒,它们的视觉比我们以前认为的要好很多。
现代昆虫和甲壳类动物都有“复眼”,它们包含数百甚至数千个独立的单眼。它们以像素的形式观察这个世界,每个单眼产生一像素视觉。更多单眼意味着有更多像素,因此目力分辨率也更好。据南澳大利亚博物馆和阿德莱德大学的科学家表示,最新发现的这些化石“复眼”由3000多个独立单眼构成,因此它们比那个时代的任何动物的视力都更好。它们也许属于一种可以在昏暗光线下看清周围一切的活跃的食肉动物。
他们的发现显示,一些最早出现的动物可能跟食虫虻等现有昆虫类似,拥有超强的视觉。在大约5.4亿年前开始的“寒武纪生命大爆发”期间第一批这种食肉动物出现后,敏锐的视觉一定进化的很快。除了好视力在躲避天敌和寻找食物及庇护所方面存在巨大的适应优势外,巨大的进化压力一定也在不断改进和提高视觉器官。由于这次发现的只有化石“复眼”,因此科学家并不清楚它们属于哪种动物,不过它们可能是一种外形像虾的大型动物的眼睛。
含有这些复眼化石的岩石里还有大量远古海洋生物化石,其中很多是以前未知的。它们包括像三叶虫的原始生物、披甲虫(armoured worms)和长着给食附属肢、会游泳的大型食肉动物。最近发现的这些化石复眼观察这个世界的像素超过3000,因此它们的拥有者在当时具有很大的视觉优势,因为同一时期的其他动物的像素大约只有100,看到的一切都非常模糊。
这种动物的视力一定比现有马蹄蟹的视力更好,但是没有现有蜻蜓的好,马蹄蟹观察周围环境的像素只有1000,而蜻蜓拥有最棒的复眼,它的像素是2.8万。该研究成果发表在《自然》杂志上。(生物谷Bioon.com)
生物谷推荐原文出处:
Nature doi:10.1038/nature10097
Modern optics in exceptionally preserved eyes of Early Cambrian arthropods from Australia
Michael S. Y. Lee, James B. Jago, Diego C. García-Bellido, Gregory D. Edgecombe, James G. Gehling & John R. Paterson
Despite the status of the eye as an “organ of extreme perfection”1, theory suggests that complex eyes can evolve very rapidly2. The fossil record has, until now, been inadequate in providing insight into the early evolution of eyes during the initial radiation of many animal groups known as the Cambrian explosion. This is surprising because Cambrian Burgess-Shale-type deposits are replete with exquisitely preserved animals, especially arthropods, that possess eyes3, 4, 5. However, with the exception of biomineralized trilobite eyes, virtually nothing is known about the details of their optical design. Here we report exceptionally preserved fossil eyes from the Early Cambrian (~515 million years ago) Emu Bay Shale of South Australia, revealing that some of the earliest arthropods possessed highly advanced compound eyes, each with over 3,000 large ommatidial lenses and a specialized ‘bright zone’. These are the oldest non-biomineralized eyes known in such detail, with preservation quality exceeding that found in the Burgess Shale and Chengjiang deposits. Non-biomineralized eyes of similar complexity are otherwise unknown until about 85 million years later6, 7. The arrangement and size of the lenses indicate that these eyes belonged to an active predator that was capable of seeing in low light. The eyes are more complex than those known from contemporaneous trilobites and are as advanced as those of many living forms. They provide further evidence that the Cambrian explosion involved rapid innovation in fine-scale anatomy as well as gross morphology, and are consistent with the concept that the development of advanced vision helped to drive this great evolutionary event.