现存爬行动物鼻甲的结构和功能,鸟,对哺乳动物进行了回顾,并检查了与哺乳动物元素吸热的关系。爬行动物耳甲相对简单,递归结构,主要带有感觉(嗅觉)上皮。相反,神甲,或者鼻甲,鸟类和哺乳动物的研究范围更加广泛和复杂,熊,此外,非感觉(呼吸)上皮。哺乳动物的鼻甲,只有完全呼吸的上颌管与吸热有明确的功能关系,因为它减少了与快速和连续肺通气相关的干燥。其他哺乳动物鼻甲主要保留原始的,鼻甲的嗅觉功能。上颌尿嘧啶是第一个可靠的吸热形态学指标,可用于化石记录。在哺乳动物化石和哺乳动物类爬行动物中,鼻甲的存在和功能最容易通过它们附着在鼻腔壁上的脊来揭示。嗅觉鼻甲的脊位于后臭位置,远离呼吸空气的主要流动,而呼吸上颌管位于鼻通道的前外侧部分,直接在呼吸的空气中。上颌骨的特征还在于其靠近鼻泪管的开口。后背脊,嗅觉鼻甲,长期以来在许多哺乳动物类爬行动物中被认可,包括pelycosaurs等早期形式。然而,在该组中,以前尚未发现呼吸鼻甲的脊。在本文中,前外侧脊的存在,最有可能支持呼吸鼻甲,据报道,在原始的河豚Glanosuchus和几个犬齿动物中。这些高级哺乳动物状爬行动物中存在呼吸鼻甲,这表明“哺乳动物”耗氧率的演变可能早在二叠纪晚期就开始了,并在海洋动物和犬齿动物中并行发展。完整的哺乳动物吸热可能需要多达40到5000万年的时间才能发展。
The structure and function of the nasal conchae of extant reptiles, birds, and mammals are reviewed, and the relationships to endothermy of the mammalian elements are examined. Reptilian conchae are relatively simple, recurved structures, which bear primarily sensory (olfactory) epithelium. Conversely, the conchae, or turbinates, of birds and mammals are considerably more extensive and complex, and bear, in addition, nonsensory (respiratory) epithelium. Of the mammalian turbinates, only the exclusively respiratory maxilloturbinal has a clear functional relationship with endothermy, as it reduces desiccation associated with rapid and continuous pulmonary ventilation. The other mammalian turbinates principally retain the primitive, olfactory function of the nasal conchae. The
maxilloturbinates are the first reliable morphological indicator of endothermy that can be used in the fossil record. In fossil mammals and mammallike reptiles, the presence and function of turbinates are most readily revealed by the ridges by which they attach to the walls of the nasal cavity. Ridges for olfactory turbinals are located posterodorsally, away from the main flow of respiratory air, whereas those of the respiratory maxilloturbinals are situated in the anterolateral portion of the nasal passage, directly in the path of respired air. The maxilloturbinal is also characterized by its proximity to the opening of the nasolacrimal canal. Posterodorsal ridges, for olfactory turbinals, have long been recognized in many mammallike reptiles, including early forms such as pelycosaurs. However, ridges for respiratory turbinals have not been identified previously in this group. In this paper, the presence of anterolateral ridges, which most likely supported respiratory turbinals, is reported in the primitive therocephalian Glanosuchus and in several cynodonts. The presence of respiratory turbinals in these advanced mammallike reptiles suggests that the evolution of \"mammalian\" oxygen consumption rates may have begun as early as the Late Permian and developed in parallel in therocephalians and cynodonts. Full mammalian endothermy may have taken as much as 40 to 50 million yr to develop.