美國(guó)古生物學(xué)家在美國(guó)國(guó)家自然歷史博物館中的暴龍骨骼化石上發(fā)現(xiàn),，這只暴龍?jiān)谂R死前發(fā)生過下頜骨病變,，并猜測(cè)是由單細(xì)胞寄生蟲滴蟲引起的,。由于下頜骨病變使得暴龍不能進(jìn)食,，最后導(dǎo)致死亡,。并且古生物學(xué)家推測(cè),，這種滴蟲可能在當(dāng)時(shí)殺死了很多暴龍,。
威斯康星大學(xué)麥迪遜分校的古生物學(xué)家伊萬·沃夫和他的同事使用現(xiàn)代猛禽的證據(jù)表明,，原生動(dòng)物寄生蟲（如滴蟲）可以引起下頜骨的病變,，并侵蝕下頜骨。
同樣,，在白堊紀(jì)時(shí)候,，這些原生寄生蟲可能引起暴龍的下頜骨的病變，進(jìn)而病變惡化可以使得暴龍無法進(jìn)食,，并在暴龍的下頜骨上穿出許多小洞,。這種疾病可能是由暴龍捕食時(shí)，或者暴龍和暴龍撕咬或者交配時(shí)傳染上的,。
沃夫說,，當(dāng)我們看到暴龍化石下頜骨上的這些洞時(shí)，我們一般認(rèn)為這是暴龍被攻擊后留下的,。但是,，有許多疾病也可以同樣在暴龍下頜骨上留下這個(gè)洞。沃夫認(rèn)為有三個(gè)證據(jù)可以表明,，這個(gè)洞不是被咬的傷口：一,，暴龍下頜骨上的這些洞非常圓滑，并不像利齒所留下的傷口外形,。二,，如果是被其他恐龍攻擊，所留下的傷口應(yīng)當(dāng)是集中在一起,，但暴龍化石下頜骨上的這些洞很分散,。三，在下頜骨上的這些洞的周圍沒有被攻擊后所應(yīng)留下的擦傷痕跡,。
加利福尼亞州西方大學(xué)的恐龍解剖學(xué)專家伊麗莎白·瑞卡（Elizabeth Rega）同樣認(rèn)為把暴龍化石下頜骨上的這些洞是由疾病一起的,，但是瑞卡認(rèn)為，引起疾病的原因是放線菌,。沃夫辯解說,，放線菌的損傷在人體來說一般都是由膿液引起。但是鳥類自身含有對(duì)纖維蛋白生物的免疫,，一般不會(huì)產(chǎn)生膿液,。同樣的原因，對(duì)于恐龍來說,，和鳥類一樣,，也不容易產(chǎn)生膿液。
瑞卡稱沃夫的理論是一個(gè)“有趣的假說”,，但是不是一個(gè)和證據(jù)完美匹配的假說,。瑞卡指出，任何病原體要在暴龍下頜骨上留下洞,，都要附著在下頜骨上很長(zhǎng)時(shí)間,，以腐蝕下頜骨,。顯然，滴蟲不具備這個(gè)特性,。
還有很多理論仍舊支持暴龍下頜骨上的洞是由咬傷引起的,。美國(guó)堪薩斯大學(xué)的病理學(xué)專家布魯斯·羅斯柴爾德（Bruce Rothschild）認(rèn)為暴龍下頜骨上的這些洞由疾病引起的理論不能成立。他認(rèn)為用現(xiàn)代猛禽的證據(jù)去證明暴龍也曾經(jīng)得過類似的疾病本身就存在問題,。而且也沒有更有力的證據(jù)可以表明這些下頜骨上的洞是由于病變引起的,。（生物谷Bioon.com）
生物谷推薦原始出處：
PLoS ONE 4(9): e7288. doi:10.1371/journal.pone.0007288
Common Avian Infection Plagued the Tyrant Dinosaurs
Ewan D. S. Wolff1*, Steven W. Salisbury2,3*, John R. Horner4, David J. Varricchio5
1 Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin, United States of America, 2 School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia, 3 Vertebrate Paleontology, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, United States of America, 4 Museum of the Rockies, Montana State University, Bozeman, Montana, United States of America, 5 Department of Earth Sciences, Montana State University, Bozeman, Montana, United States of America
Background
Tyrannosaurus rex and other tyrannosaurid fossils often display multiple, smooth-edged full-thickness erosive lesions on the mandible, either unilaterally or bilaterally. The cause of these lesions in the Tyrannosaurus rex specimen FMNH PR2081 (known informally by the name ‘Sue’) has previously been attributed to actinomycosis, a bacterial bone infection, or bite wounds from other tyrannosaurids.
Methodology/Principal Findings
We conducted an extensive survey of tyrannosaurid specimens and identified ten individuals with full-thickness erosive lesions. These lesions were described, measured and photographed for comparison with one another. We also conducted an extensive survey of related archosaurs for similar lesions. We show here that these lesions are consistent with those caused by an avian parasitic infection called trichomonosis, which causes similar abnormalities on the mandible of modern birds, in particular raptors.
Conclusions/Significance
This finding represents the first evidence for the ancient evolutionary origin of an avian transmissible disease in non-avian theropod dinosaurs. It also provides a valuable insight into the palaeobiology of these now extinct animals. Based on the frequency with which these lesions occur, we hypothesize that tyrannosaurids were commonly infected by a Trichomonas gallinae-like protozoan. For tyrannosaurid populations, the only non-avian dinosaur group that show trichomonosis-type lesions, it is likely that the disease became endemic and spread as a result of antagonistic intraspecific behavior, consumption of prey infected by a Trichomonas gallinae-like protozoan and possibly even cannibalism. The severity of trichomonosis-related lesions in specimens such as Tyrannosaurus rex FMNH PR2081 and Tyrannosaurus rex MOR 980, strongly suggests that these animals died as a direct result of this disease, mostly likely through starvation.
