Abstract:
The cetacean nose presents a unique suite of anatomical modifications. Key among these is posterior movement of the external nares from the tip of the rostrum to the top of the head. Concomitant with these anatomical changes are functional changes including the evolution of echolocation in odontocetes, and reduction of olfaction in Neoceti (crown odontocetes and mysticetes). Anatomical and embryological development of the nose in crown cetaceans is reviewed as well as their functional implications. A sequence of evolutionary transformations of the nose is proposed in the transition from a terrestrial to an aquatic lifestyle made by whales. Basilosaurids and all later whales reduce the nasal turbinates. The next stage characterizes Neoceti which exhibit reduction of the major olfactory structures, i.e. the ethmoturbinates, cribriform plate and maxilloturbinates with further reduction and subsequent loss in odontocetes. These anatomical modifications reflect underlying genetic changes such as the reduction of olfactory receptor genes, although mysticetes retain some olfactory abilities. Modifications of the facial and nasal region of odontocetes reflect specialization for biosonar sound production.
摘要:
鲸目动物的鼻子呈现了一套独特的解剖学修饰。其中的关键是外部鼻孔从讲台的尖端向头部顶部的向后移动。伴随着这些解剖学变化的是功能变化,包括齿状体回声定位的演变,和减少嗅觉在新科(冠齿科和神秘主义)。综述了冠鲸类动物鼻子的解剖和胚胎学发育及其功能意义。在鲸鱼从陆地生活方式过渡到水生生活方式的过程中,提出了鼻子的一系列进化转变。鼻甲和所有后来的鲸鱼都会减少鼻甲。下一阶段的特征是Neoceti表现出主要嗅觉结构的减少,即乙醇酸,筛状钢板和上颌钳状,进一步减少并随后丢失。这些解剖学修饰反映了潜在的遗传变化,例如嗅觉受体基因的减少,虽然神秘主义者保留了一些嗅觉能力。牙骨的面部和鼻腔区域的修饰反映了生物声纳声音产生的专业化。