與人類頭骨相比，霸王龍的頭骨處于中空狀態(tài),。這種充滿竇腔結構的頭部更輕,，從而提高了堅固度
目前，科學家最新一項研究揭示,，像霸王龍等一些兇殘恐龍頭部處于中空狀態(tài)，里面有許多空氣,，這樣可使恐龍頭部負荷減輕,，或許充當著與其他恐龍進行交流通信的“共振室”(resonating chambers)作用。
美國俄亥俄州大學研究員勞倫斯·威特默(Lawrence Witmer)說,，“我們知道恐龍的大腦很小,，因此曾推測它的頭骨處于中空狀態(tài)，目前這項最新研究證實了之前推測的真實性,。”該研究結果進一步支持了威特默和同事們之前的一項研究,，他們曾發(fā)現(xiàn)鴨嘴龍頭骨中的氣室部分有助于它們鼻腔發(fā)聲，或許由此產生清晰的“聲音”,。
威特默和俄亥俄州大學同事賴安·里奇利(Ryan Ridgely)使用計算機斷層攝影技術掃描了兩種掠食性恐龍(霸王龍和瑪君龍)的頭骨,，同時還對胄甲龍和包頭龍這兩種食草性“披甲”恐龍進行了掃描。三維掃描結果顯示,，較大的鼻腔區(qū)域中彎曲的通氣道從鼻孔延伸至咽喉和幾處竇腔,，總體來講，恐龍頭骨內充滿空氣的區(qū)域大于腦腔,。
頭骨中空區(qū)域有助于減輕霸王龍頭部負荷重量,，這樣的中空結構將比一個固體實心頭骨輕18%，他們評估一顆完全是由肉質構成的霸王龍頭部重量很可能超過500公斤(1100磅),，然而實際上瑪君龍的頭骨僅重32公斤(70磅),，如果霸王龍的頭骨完全由骨質構成，其重量為數(shù)百磅,。
頸部肌肉和其他身體特征僅起到將恐龍頭部抬起的作用,，而頭骨中空結構卻能有助于減輕頭部重量，中空的骨骼結構將使霸王龍和瑪君龍的頭骨變得更加強壯,，比如：這種頭骨結構能夠輔助口腔肌肉咬碎骨骼或撕裂大型獵物尸體,。
如同空心管可使建筑物更加堅固，恐龍頭骨中的竇腔結構可使頭部骨骼更加堅固,，而且重量更輕,。擁有更輕、更堅固的頭部，霸王龍等恐龍便能快速地轉動頭部,。
威特默稱,，長有“披甲”的食草恐龍與眾不同，它們不同于掠食性恐龍的筆直鼻腔氣道,，研究人員發(fā)現(xiàn)食草恐龍的鼻腔氣道比較卷曲復雜,，有點兒像彎彎曲曲的稻草麥稈。他們發(fā)現(xiàn)彎曲的氣道在較大血管的周圍,，表明這起到一種熱量轉換作用,。因此，當披甲恐龍吸入空氣時,，在氣體進入肺部時就已被周圍的血管加熱,。此外，由血管釋放的一些熱量將中和進入鼻腔的空氣溫度,，避免空氣進入頭部將血液冷卻,。
威特默在接受美國生活科學網記者采訪時說，“彎曲的鼻腔氣道或許還充當著共振室的作用,，影響甲龍等恐龍如何發(fā)出聲音,，每種恐龍的氣道都可能存在著微妙的差別。”目前,，這項最新研究報告發(fā)表在近期出版的《解剖學記錄》（The Anatomical Record）雜志上,。（生物谷Bioon.com）
生物谷推薦原始出處：
The Anatomical Record，Volume 291 Issue 11, Pages 1362 - 1388,，Lawrence M. Witmer,，Ryan C. Ridgely
The Paranasal Air Sinuses of Predatory and Armored Dinosaurs (Archosauria: Theropoda and Ankylosauria) and Their Contribution to Cephalic Structure
Lawrence M. Witmer *, Ryan C. Ridgely
Department of Biomedical Sciences, College of Osteopathic Medicine, Ohio University, Athens, Ohio
The paranasal air sinuses and nasal cavities were studied along with other cephalic spaces (brain cavity, paratympanic sinuses) in certain dinosaurs via CT scanning and 3D visualization to document the anatomy and examine the contribution of the sinuses to the morphological organization of the head as a whole. Two representatives each of two dinosaur clades are compared: the theropod saurischians Majungasaurus and Tyrannosaurus and the ankylosaurian ornithischians Panoplosaurus and Euoplocephalus. Their extant archosaurian outgroups, birds and crocodilians (exemplified by ostrich and alligator), display a diversity of paranasal sinuses, yet they share only a single homologous antorbital sinus, which in birds has an important subsidiary diverticulum, the suborbital sinus. Both of the theropods had a large antorbital sinus that pneumatized many of the facial and palatal bones as well as a birdlike suborbital sinus. Given that the suborbital sinus interleaves with jaw muscles, the paranasal sinuses of at least some theropods (including birds) were actively ventilated rather than being dead-air spaces. Although many ankylosaurians have been thought to have had extensive paranasal sinuses, most of the snout is instead (and surprisingly) often occupied by a highly convoluted airway. Digital segmentation, coupled with 3D visualization and analysis, allows the positions of the sinuses to be viewed in place within both the skull and the head and then measured volumetrically. These quantitative data allow the first reliable estimates of dinosaur head mass and an assessment of the potential savings in mass afforded by the sinuses.
