脊椎动物内耳迷路的形态与演化

Morphology and evolution of the labyrinth of vertebrate inner ear

脊椎动物内耳迷路是听觉和平衡觉器官,对其形态和结构的研究已经有很长的历史。近年来,高精度X射线计算机断层扫描技术被广泛应用于化石脊椎动物内耳迷路的研究。通过测量对比和多元统计分析,可以预测或估计动物的运动方式。从演化的角度来看,内耳迷路的半规管部分、前庭窗和前庭水管都是非常稳定的结构,自四足动物首次出现以来,这些结构的基本形态和空间位置关系一直保持不变。相反,内耳的压力释放机制经历了复杂的趋同演化过程,不同脊椎动物类群中被称为蜗窗、外淋巴孔、蜗水管等的结构并不一定都是同源的。耳蜗的延长和弯曲也发生了很多次,发育有骨螺旋板和第二螺旋板、并呈蜗牛状卷曲的耳蜗只发生在树掠兽类+文氏掠兽+后兽类+真兽类这一支系中。

The labyrinth of vertebrate inner ear contains the organs responsible for the senses of hearing and equilibrium. Research on the morphology and function of this delicate structure has a very long history. In recent years, the sophisticated high resolution X-ray computed tomography has been widely applied in the research on the labyrinth of fossil vertebrate inner ear. Based on multivariable statistic analysis and metrical comparison with the analogs of extant species, the activity pattern of the fossil animals can be predicted or estimated. From an evolutionary perspective, the semicircular part of the labyrinth, fenestra vestibuli and aqueductus vestibuli are very stable structure. The fundamental morphology and special arrangements of these structures keep unchanged since the first appearance of the tetrapods. The press release mechanism of the inner ear underwent very complicated convergent evolution. Press release foramens termed as fenestra cochleae, perilymphatic foramen, or aqueductus cochleae are not always homologous across different vertebrate groups. The elongation and curving of the cochlea also occurred many times. Snail-like curving, coupled with the development of the lamina spiralis ossea and lamina spiralis secundaria, occurred only in the clade consist of Dryolestoidea ＋ Vincelestes ＋ metatherians ＋ eutherians.