Reassessment of the evidence for postcranial skeletal pneumaticity in Triassic archosaurs, and the early evolution of the avian respiratory system.
Reassessment of the evidence for postcranial skeletal pneumaticity in Triassic archosaurs, and the early evolution of the avian respiratory system.
复制标题
DOI：
10.1371/journal.pone.0034094
复制
发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Gower DJ
中科院分区：
文献类型：
--
作者：
Butler RJ;Barrett PM;Gower DJ
在现存的脊椎动物中，鸟类具有复杂的呼吸系统，其特征在于小而坚硬的肺、具有侵入（使颅后骨骼变细）的憩室的广泛的肺气囊、肺的单向通气和有效的横流气体交换的组合。鳄龙是现存的唯一一种主龙，也拥有单向的肺通气功能，但缺乏真正的气囊和颅后骨骼运动（PSP）。PSP可以用来推断在几个已灭绝的主龙类分支（非鸟类兽脚亚目恐龙，蜥脚亚目恐龙和翼龙）中存在类似鸟类的肺气囊。然而，其他主龙类的呼吸系统的演化，特别是在鳄鱼类的谱系中，却很少有文献记载。在这里，我们使用µ CT扫描来研究三叠纪主龙分类群的脊椎解剖学，包括鸟类和鳄鱼谱系以及非主龙类双壳类外类群。我们的研究结果证实了以前的建议，明确的证据PSP（存在内部气动腔连接到外部的孔）被发现只在鸟线（ornithodiran）的主龙。我们认为肺气囊存在于鸟颈龙的共同祖先中，并且可能随后在该分支的某些成员中丢失或减少（特别是在鸟臀目恐龙中）。这些类似鸟类的呼吸特征的发展可能与推测的鸟龙类活动水平的增加有关。相比之下，没有鳄线主龙（伪鳄目）表现出明确的PSP证据，但这些类群中的许多具有复杂的椎板和窝阵列，总是伴随着在鸟龙类气囊的存在。这些纹层和窝很可能与鸟龙类的纹层和窝同源，这表明需要进一步研究这样一种假设，即一个减少的或非侵入性的肺气囊系统可能已经存在于这些分类群中（其次在现存的鳄龙类中丢失），并且可能是整个初龙类的原始系统。
Uniquely among extant vertebrates, birds possess complex respiratory systems characterised by the combination of small, rigid lungs, extensive pulmonary air sacs that possess diverticula that invade (pneumatise) the postcranial skeleton, unidirectional ventilation of the lungs, and efficient crosscurrent gas exchange. Crocodilians, the only other living archosaurs, also possess unidirectional lung ventilation, but lack true air sacs and postcranial skeletal pneumaticity (PSP). PSP can be used to infer the presence of avian-like pulmonary air sacs in several extinct archosaur clades (non-avian theropod dinosaurs, sauropod dinosaurs and pterosaurs). However, the evolution of respiratory systems in other archosaurs, especially in the lineage leading to crocodilians, is poorly documented. Here, we use µCT-scanning to investigate the vertebral anatomy of Triassic archosaur taxa, from both the avian and crocodilian lineages as well as non-archosaurian diapsid outgroups. Our results confirm previous suggestions that unambiguous evidence of PSP (presence of internal pneumatic cavities linked to the exterior by foramina) is found only in bird-line (ornithodiran) archosaurs. We propose that pulmonary air sacs were present in the common ancestor of Ornithodira and may have been subsequently lost or reduced in some members of the clade (notably in ornithischian dinosaurs). The development of these avian-like respiratory features might have been linked to inferred increases in activity levels among ornithodirans. By contrast, no crocodile-line archosaur (pseudosuchian) exhibits evidence for unambiguous PSP, but many of these taxa possess the complex array of vertebral laminae and fossae that always accompany the presence of air sacs in ornithodirans. These laminae and fossae are likely homologous with those in ornithodirans, which suggests the need for further investigation of the hypothesis that a reduced, or non-invasive, system of pulmonary air sacs may be have been present in these taxa (and secondarily lost in extant crocodilians) and was potentially primitive for Archosauria as a whole.
登录
查看更多内容
影响因子：
3.3
作者：
Butler, Richard J.;Barrett, Paul M.;Gower, David J.
通讯作者：
Gower, David J.
影响因子：
3.7
作者：
Butler RJ;Brusatte SL;Reich M;Nesbitt SJ;Schoch RR;Hornung JJ
通讯作者：
Hornung JJ
影响因子：
64.8
作者：
Britt, BB;Makovicky, PJ;Bonde, N
通讯作者：
Bonde, N
DOI：
10.1144/gsl.sp.2003.217.01.13
发表时间：
2003-01-01
期刊：
Geological Society Special Publication
影响因子：
--
作者：
Bonde, Niels;Christiansen, Per
通讯作者：
Christiansen, Per
影响因子：
12.1
作者：
Brusatte, Stephen L.;Nesbitt, Sterling J.;Norell, Mark A.
通讯作者：
Norell, Mark A.