最古老的草食蜥蜴

    A rare fossil discovered in Japan is the oldest known plant-eating lizard, which could shed light on an evolutionary puzzle that Charles Darwin described as an "abominable mystery," scientists say. The 130-million-year-old jaw and skull bones were unearthed in the Ishikawa Prefecture of Japan (see map of Japan).
    一具非常稀有的化石在日本被发现，这是目前已知的最古老的食草蜥蜴。科学家们说，此发现可能解开达尔文所谓的进化难题――“令人讨厌的神秘”。在日本石川县发现了1.3亿年前的颚骨和头盖骨。

    Based on the size of the skull, the researchers estimate that the lizard measured between 10 to 12 inches (25 to 30 centimeters ) in length.
    根据头盖骨的尺寸，研究者推测蜥蜴的长度大概在10至12英寸（25－30厘米）。

    Prior to the new discovery, the oldest known plant-eating lizard was Dicothodon, which lived in North America about 100 million years ago.
    在此之前，最古老的食草蜥蜴是大约1亿前生活在北美的“Dicothodon”

    Even today, fully herbivorous, or plant-eating, lizards are rare, with only about 3 percent of modern lizards belonging to the group. Most lizards eat flesh, usually insects, or a combination of flesh and plants.
    而今真正食草的蜥蜴很稀少，只有大约3%的现今蜥蜴属于这一群落。而大多数蜥蜴吃肉或肉和草都吃，而它们吃的肉通常是昆虫。

    Modern herbivorous lizards eat flowering plants, or angiosperms, whose buds and leaves are typically softer than nonflowering plants.
    现代食草蜥蜴吃开花植物或被子植物，它们的叶芽通常比不开花的植物柔软。

    Thus the new fossil species, dubbed Kuwajimalla kagaensis, could indicate that angiosperms were already in existence and perhaps widespread millions of years earlier than had been thought, the researchers say.
    因此科学家表示，这种被命名为“Kuwajimalla kagaensis”新化石蜥蜴的发现表明被子植物比我们想象的早数百万年就存在并广泛分布了。此发现发表在最新出版的《古生物学》杂志上。

    "By finding this particular fossil from Japan, it might suggest that flowering plants were already there, but we don't have direct evidence yet," said study team member Makoto Manabe of Japan's National Science Museum in Tokyo.
    “根据在日本发现的化石细节，可能意味着开花植物很久以前就在那里了，但我们还没有直接的证据。”日本东京的国家科学博物馆研究团队成员Makoto Manabe 说。

    The discovery is detailed in a recent issue of the journal Paleontology.
    此发现发表在最新出版的古生物学杂志上。

    Darwin's Dilemma
    达尔文的困惑

    Currently the oldest evidence a flowering plant is a 125-million-year-old fossil from China.
    最近最古老的开花主物的证据来自于中国的1.25亿年前的化石。

    The apparently sudden appearance of angiosperms in the fossil record confounded Darwin, who worried that it might pose a problem for his theory of evolution by natural selection.
    开花植物在化石记录中的突然出现令达尔文很疑惑，他担心这可能对他 的自然选择导致进化的理论造成问题。

    Scientists have since uncovered fossils tracing the evolution of angiosperms from nonflowering plants, called gymnosperms.
    科学家发现了被子植物从不开花植物（裸子植物）演化而来的化石踪迹

    The K. kagaensis fossil was unearthed in 2001, but it was only with recent analysis by Manabe and Susan Evan, a paleontologist at the University College London, that its significance was realized.
    K. kagaensis化石发现于2001年，但它只是最近被Manabe和Susan Evan（伦敦大学古生物学家）分析研究，它的重要性被意识到了。

    "We noticed the importance by looking at the teeth," Manabe said. "It's so rare, and it's so old."
    “我们在看到那些牙齿的时候，注意到其中的重要性。”Manabe说“它非常罕有，非常古老。”

    The lizard's teeth were similar to those of modern day iguanas, which are one of the few fully herbivorous lizards alive today.
    这个蜥蜴的牙齿有些和现代的那些鬣蜥相似，它们是现存很少的真正食草蜥蜴之一。

    The researchers think the animal dined on some of the world's first flowers.
    研究者们猜想这种生物以世界上第一批开花植物为食。

    Modern gymnosperms such as ferns and gingko are typically not very nutritious and are tougher to chew than angiosperms.
    现代裸子植物，诸如蕨类植物和银杏，和被子植物相比明显的非常没有营养和粗硬

    "If you're a dinosaur, your jaw is bigger, so it's OK," Manabe said.
    “假如你是一只恐龙，你的上下颚大得多，这当然没问题。” Manabe说

    "But lizards are small, and they have delicate teeth, so it is very difficult for them to eat and chop off very tough material."
    “但蜥蜴是很小的，它们只有脆弱的牙齿，因此它们很难取食和咀嚼非常粗硬的材料。”

    Alternatively, K. kagaensis might also have fed on young gymnosperm leaves, the researchers say.
    研究者说也有可能是K. kagaensis以那些裸子植物的嫩叶为食物。

    "The big leaves are tough and fibrous," Manabe said. "But the young ones tend to be softer and smaller."
    “大叶子又硬又多纤维。”Manabe说。“但小的可能更柔软更小。”

    Christopher Austin, a herpetologist and curator at Louisiana State University's Museum of Natural Science, called the fossil discovery a "spectacular" find that challenges long-held views about lizard evolution.
    Christopher Austin，路易斯安那州大学自然科学博物馆爬虫学专家和馆长，称这个化石发现是“引人入胜的”，此发现挑战有关蜥蜴进化的一个长久观点。

    "The ancestral condition for lizards has always been assumed to be insectivorous [insect-eating], so this new fossil provides data that challenges this thinking," Austin said.
    “蜥蜴祖先所处的环境让人们一直认为它们是吃昆虫的，新化石提供的证据挑战了这个想法。” Austin说。

    He added that the anatomical features of K. kagaensis suggest "that either the ancestral condition for lizard diet was not as restricted as once thought or that diet has been highly labile [easily changed] throughout lizard evolution."
    他补充说K. kagaensis 的解剖学形态暗示“蜥蜴祖先的取食并不像我们过去所想的那样受限，或者说，在演化的历程中，它们可能是很容易变化的。”