Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.
CAS Center for Excellence in Life and Paleoenvironment, Beijing, China.
PLoS One. 2018 Jun 20;13(6):e0198078. doi: 10.1371/journal.pone.0198078. eCollection 2018.
The tongue, with fleshy, muscular, and bony components, is an innovation of the earliest land-dwelling vertebrates with key functions in both feeding and respiration. Here, we bring together evidence from preserved hyoid elements from dinosaurs and outgroup archosaurs, including pterosaurs, with enhanced contrast x-ray computed tomography data from extant taxa. Midline ossification is a key component of the origin of an avian hyoid. The elaboration of the avian tongue includes the evolution of multiple novel midline hyoid bones and a larynx suspended caudal to these midline elements. While variable in dentition and skull shape, most bird-line archosaurs show a simple hyoid structure. Bony, or well-mineralized, hyoid structures in dinosaurs show limited modification in response to dietary shifts and across significant changes in body-size. In Dinosauria, at least one such narrow, midline element is variably mineralized in some basal paravian theropods. Only in derived ornithischians, pterosaurs and birds is further significant hyoid elaboration recorded. Furthermore, only in the latter two taxa does the bony tongue structure include elongation of paired hyobranchial elements that have been associated in functional studies with hyolingual mobility. Pterosaurs and enantiornithine birds achieve similar elongation and inferred mobility via elongation of ceratobranchial elements while within ornithurine birds, including living Aves, ossified and separate paired epibranchial elements (caudal to the ceratobranchials) confer an increase in hyobranchial length. The mobile tongues seen in living birds may be present in other flighted archosaurs showing a similar elongation. Shifts from hypercarnivory to more diverse feeding ecologies and diets, with the evolution of novel locomotor strategies like flight, may explain the evolution of more complex tongue function.
舌由肉质、肌肉和骨骼成分组成，是最早的陆生脊椎动物的创新，在进食和呼吸中都有重要作用。在这里，我们结合了恐龙和外群主龙类（包括翼龙）保存的舌骨元素以及来自现存分类群的增强对比 X 射线计算机断层扫描数据的证据。中线骨化是鸟类舌骨起源的关键组成部分。鸟类舌头的复杂化包括多个新的中线舌骨的演变，以及一个位于这些中线元素下方的悬垂喉。尽管在牙齿和头骨形状上存在差异，但大多数鸟类主龙类都显示出简单的舌骨结构。骨骼化或矿化良好的恐龙舌骨结构对饮食变化和体型显著变化的响应受到限制。在恐龙中，至少有一种这样的狭窄中线元素在一些基础兽脚亚目恐龙中是可变矿化的。只有在衍生的鸟脚类恐龙、翼龙和鸟类中，才记录到进一步的显著舌骨复杂化。此外，只有在后两类中，骨舌结构包括对成对的舌颌骨元素的伸长，这些元素在功能研究中与舌咽运动性相关。翼龙和反鸟类通过延长角舌骨元素实现了类似的伸长和推断的运动性，而在鸟类中，包括现存的鸟类，骨化和分离的成对的咽上骨元素（角舌骨的下方）增加了舌颌骨的长度。在现生鸟类中看到的可移动的舌头可能存在于具有类似伸长的其他飞行主龙类中。从超级肉食性向更多样化的进食生态和饮食的转变，以及新型运动策略（如飞行）的进化，可能解释了更复杂的舌功能的进化。
