Postcranial pneumatization in Archaeopteryx
Postcranial pneumatization in Archaeopteryx
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作者：
Britt, BB;Makovicky, PJ;Bonde, N
后颅骨骼的肺充气被认为是鸟类骨骼的标志，是通过减轻体重来适应飞行，然而，在原始鸟类始祖鸟中，气动特征仍然难以捉摸。始祖鸟的中空长骨最初被解释为是骨化的（1），但后来这种解释被拒绝，因为这些骨头中没有连接其内部与呼吸系统的充气孔（2-6）。在许多非鸟类的兽脚亚目恐龙（以及其他鸟形目的主龙）的中轴骨骼中也发现了气动特征。据称始祖鸟缺乏颅后气动特征，这被解释为鸟类的原始状态;这引起了对鸟类和非鸟类兽脚类动物颅后气动特征之间同源性的怀疑（7）。在这里，我们重新检查两个标本的始祖鸟这些标本显示的证据，在颈椎和前胸椎的脊椎骨的压缩性，从而证实了非鸟类兽脚类和活的鸟类的气动系统之间的系统发育的连续性。
Pneumatization of the postcranial skeleton by the lungs is thought to be a hallmark of the avian skeleton, and to be an adaptation for flight by reducing weight, Pneumatic features have, however, remained elusive in the primitive avialan Archaeopteryx lithographica. The hollow long bones of Archaeopteryx were first interpreted to be pneumatized(1), but this interpretation was later rejected because of an absence of pneumatic foramina in these bones that connect their interiors with the respiratory system(2-6). Pneumatic features have also been recognized in the axial skeleton of many non-avialan theropod dinosaurs (and some other archosaurs of the bird dade). The purported lack of postcranial pneumatic features in Archaeopteryx has been interpreted as a primitive condition of avialans; this raises doubts about the homology between postcranial pneumatic features of birds and non-avialan theropods(7). Here we re-examine two specimens of Archaeopteryx These specimens show evidence of vertebral pneumaticity in the cervical and anterior thoracic vertebrae, thus confirming the phylogenetic continuity between the pneumatic systems of non-avialan theropods and living birds.