Ankylosaurid dinosaur tail clubs evolved through stepwise acquisition of key features
Ankylosaurid dinosaur tail clubs evolved through stepwise acquisition of key features
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DOI：
10.1111/joa.12363
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发表时间：
2015-10-01
影响因子：
2.4
通讯作者：
Currie, Philip J.
中科院分区：
文献类型：
--
作者：
Arbour, Victoria M.;Currie, Philip J.
甲龙是四足食草性恐龙，有丰富的皮肤骨化。它们以其独特的尾巴而闻名，尾巴由僵硬的、相互关联的脊椎(手柄)和巨大的球茎状骨皮(球茎)组成，这可能被用作武器。然而，尾棒在甲龙进化中出现的时间相对较晚，似乎只出现在中生代最后2000万年的甲龙派生支系中。来自中国的白垩纪中期化石的新证据表明，尾棒的进化发生在至少4,000万年前，并且是以一种循序渐进的方式发生的，早期的甲龙进化出手柄状的脊椎骨，然后远端的骨皮扩大并骨化形成节状。
Ankylosaurid ankylosaurs were quadrupedal, herbivorous dinosaurs with abundant dermal ossifications. They are best known for their distinctive tail club composed of stiff, interlocking vertebrae (the handle) and large, bulbous osteoderms (the knob), which may have been used as a weapon. However, tail clubs appear relatively late in the evolution of ankylosaurids, and seemed to have been present only in a derived clade of ankylosaurids during the last 20 million years of the Mesozoic Era. New evidence from mid Cretaceous fossils from China suggests that the evolution of the tail club occurred at least 40 million years earlier, and in a stepwise manner, with early ankylosaurids evolving handle-like vertebrae before the distal osteoderms enlarged and coossified to form a knob.