Editing Allosaurus (section)

===Paleopathology===
[[File:Allosaurus fragilis USNM4734.jpg|thumb|Mounted ''A. fragilis'' skeleton (USNM 4734), which has several healed injuries]]
In 2001, Bruce Rothschild and others published a study examining evidence for [[stress fracture]]s and [[tendon avulsion]]s in [[theropod]] dinosaurs and the implications for their behavior. Since stress fractures are caused by repeated trauma rather than singular events they are more likely to be caused by the behavior of the animal than other kinds of injury. Stress fractures and tendon avulsions occurring in the forelimb have special behavioral significance since while injuries to the feet could be caused by running or [[animal migration|migration]], resistant prey items are the most probable source of injuries to the hand. ''Allosaurus'' was one of only two theropods examined in the study to exhibit a tendon avulsion, and in both cases the avulsion occurred on the forelimb. When the researchers looked for stress fractures, they found that ''Allosaurus'' had a significantly greater number of stress fractures than ''[[Albertosaurus]]'', ''[[Ornithomimus]]'' or ''[[Archaeornithomimus]]''. Of the 47 hand bones the researchers studied, three were found to contain stress fractures. Of the feet, 281 bones were studied and 17 were found to have stress fractures. The stress fractures in the foot bones "were distributed to the [[proximal]] [[phalanges]]" and occurred across all three weight-bearing toes in "statistically indistinguishable" numbers. Since the lower end of the third metatarsal would have contacted the ground first while an allosaur was running, it would have borne the most stress. If the allosaurs' stress fractures were caused by damage accumulating while walking or running this bone should have experience more stress fractures than the others. The lack of such a bias in the examined ''Allosaurus'' fossils indicates an origin for the stress fractures from a source other than running. The authors conclude that these fractures occurred during interaction with prey, like an allosaur trying to hold struggling prey with its feet. The abundance of stress fractures and avulsion injuries in ''Allosaurus'' provide evidence for "very active" predation-based rather than scavenging diets.<ref name="rothschild-dino">Rothschild, B., Tanke, D. H., and Ford, T. L., 2001, Theropod stress fractures and tendon avulsions as a clue to activity: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and [[Kenneth Carpenter|Carpenter, K.]], Indiana University Press, p. 331–336.</ref>

The left [[scapula]] and [[fibula]] of an ''Allosaurus fragilis'' specimen cataloged as USNM 4734 are both pathological, both probably due to healed fractures. The specimen USNM 8367 preserved several pathological gastralia which preserve evidence of healed fractures near their middle. Some of the fractures were poorly healed and "formed pseudoarthroses". A specimen with a fractured rib was recovered from the [[Cleveland-Lloyd Dinosaur Quarry|Cleveland-Lloyd Quarry]]. Another specimen had fractured ribs and fused vertebrae near the end of the tail. An apparent subadult male ''Allosaurus fragilis'' was reported to have extensive pathologies, with a total of fourteen separate injuries. The specimen MOR 693 had pathologies on five ribs, the sixth neck vertebra, the third, eighth, and thirteenth back vertebrae, the second tail vertebra and its chevron, the [[gastralia]] right scapula, manual phalanx I left [[Ilium (bone)|ilium]] metatarsals III and V, the first phalanx of the third toe and the third phalanx of the second. The ilium had "a large hole...caused by a blow from above". The near end of the first phalanx of the third toe was afflicted by an [[involucrum]].<ref name="molnar-pathology"/>

Additionally, a subadult ''Allosaurus'' individual that suffered from [[spondyloarthropathy]] has been discovered in Dana Quarry in Wyoming. This finding represents the first known fossil evidence of spondyloarthropathy occurring in a theropod.<ref>{{Cite journal |last1=Xing |first1=Lida |last2=Rothschild |first2=Bruce M. |last3=Du |first3=Chunlei |last4=Wang |first4=Donghao |last5=Wen |first5=Kexiang |last6=Su |first6=Jiayin |date=January 2, 2024 |title=New palaeopathology cases of Allosaurus fragilis (Dinosauria: Theropoda) |url=https://www.tandfonline.com/doi/full/10.1080/08912963.2022.2155817 |journal=[[Historical Biology]] |language=en |volume=36 |issue=1 |pages=203–208 |doi=10.1080/08912963.2022.2155817 |bibcode=2024HBio...36..203X |issn=0891-2963 |access-date=June 29, 2024 |via=Taylor and Francis Online}}</ref>
[[File:Allosaurus "Big Al II".jpg|thumb|Skeletal restoration of "Big Al II" showing bones with pathologies]]
Other pathologies reported in ''Allosaurus'' include:<ref name=Chin09/><ref name="molnar-pathology">{{cite book|last=Molnar |first=R.E. |year=2001 |chapter=Theropod paleopathology: a literature survey |title=Mesozoic Vertebrate Life |editor1-last=Tanke |editor1-first=D.H. |editor2-last=Carpenter |editor2-first=K. |publisher=Indiana University Press |pages=337–363}}</ref><!--<ref>{{Cite web|url=https://paleorxiv.org/f3rh6/|access-date=February 11, 2023|website=paleorxiv.org|doi=10.31233/osf.io/f3rh6}}</ref>-->
* [[Willow breaks]] in two ribs
* Healed fractures in the [[humerus]] and [[Radius (bone)|radius]]
* Distortion of [[joint]] surfaces in the foot, possibly due to [[osteoarthritis]] or developmental issues
* [[Osteopetrosis]] along the endosteal surface of a [[tibia]].
* Distortions of the joint surfaces of the tail vertebrae, possibly due to [[osteoarthritis]] or developmental issues
* "[E]xtensive '[[neoplastic]]' [[ankylosis]] of caudals", possibly due to physical trauma, as well as the fusion of chevrons to centra
* Coossification of vertebral centra near the end of the tail
* [[Amputation]] of a chevron and foot bone, both possibly a result of bites
* "[E]xtensive [[exostoses]]" in the first phalanx of the third toe
* Lesions similar to those caused by [[osteomyelitis]] in two [[scapulae]]
* [[Bone spurs]] in a [[premaxilla]], [[ungual]], and two [[metacarpals]]
* Exostosis in a pedal phalanx possibly attributable to an infectious disease
* A metacarpal with a round depressed fracture