16世纪的西班牙文献强调钢剑是备受喜爱的兵器。
Spanish documents from the 16th century emphasize steel swords as a favored military weapon.
然而剑齿龟生活的年代还没有草生长，因而食物来源可能是二叠纪植物群的茎或叶。
Grasses did not exist at that time but it may have fed on stems or leaves of Permian flora.
因而前寒武纪化石的缺失和寒武纪三叶虫等突发式出现，好象一把双刃剑，对达尔文演化学说的塔基构成了威胁。
Therefore the deficiency of pre-Cambrian fossil and the sudden emergence of Cambrian trilobite are like a double edged sword posing threat for the very foundation of Darwin evolutionism.
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