美国古生物学家在美国国家自然历史博物馆中的暴龙骨骼化石上发现，这只暴龙在临死前发生过下颌骨病变，并猜测是由单细胞寄生虫滴虫引起的。由于下颌骨病变使得暴龙不能进食，最后导致死亡。并且古生物学家推测，这种滴虫可能在当时杀死了很多暴龙。

威斯康星大学麦迪逊分校的古生物学家伊万·沃夫和他的同事使用现代猛禽的证据表明，原生动物寄生虫（如滴虫）可以引起下颌骨的病变，并侵蚀下颌骨。

同样，在白垩纪时候，这些原生寄生虫可能引起暴龙的下颌骨的病变，进而病变恶化可以使得暴龙无法进食，并在暴龙的下颌骨上穿出许多小洞。这种疾病可能是由暴龙捕食时，或者暴龙和暴龙撕咬或者交配时传染上的。

沃夫说，当我们看到暴龙化石下颌骨上的这些洞时，我们一般认为这是暴龙被攻击后留下的。但是，有许多疾病也可以同样在暴龙下颌骨上留下这个洞。沃夫认为有三个证据可以表明，这个洞不是被咬的伤口：一，暴龙下颌骨上的这些洞非常圆滑，并不像利齿所留下的伤口外形。二，如果是被其他恐龙攻击，所留下的伤口应当是集中在一起，但暴龙化石下颌骨上的这些洞很分散。三，在下颌骨上的这些洞的周围没有被攻击后所应留下的擦伤痕迹。

加利福尼亚州西方大学的恐龙解剖学专家伊丽莎白·瑞卡（Elizabeth Rega）同样认为把暴龙化石下颌骨上的这些洞是由疾病一起的，但是瑞卡认为，引起疾病的原因是放线菌。沃夫辩解说，放线菌的损伤在人体来说一般都是由脓液引起。但是鸟类自身含有对纤维蛋白生物的免疫，一般不会产生脓液。同样的原因，对于恐龙来说，和鸟类一样，也不容易产生脓液。

瑞卡称沃夫的理论是一个“有趣的假说”，但是不是一个和证据完美匹配的假说。瑞卡指出，任何病原体要在暴龙下颌骨上留下洞，都要附着在下颌骨上很长时间，以腐蚀下颌骨。显然，滴虫不具备这个特性。

还有很多理论仍旧支持暴龙下颌骨上的洞是由咬伤引起的。美国堪萨斯大学的病理学专家布鲁斯·罗斯柴尔德（Bruce Rothschild）认为暴龙下颌骨上的这些洞由疾病引起的理论不能成立。他认为用现代猛禽的证据去证明暴龙也曾经得过类似的疾病本身就存在问题。而且也没有更有力的证据可以表明这些下颌骨上的洞是由于病变引起的。

原始出处：

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.