TABULATION OF DISEASES 6Z6 



V. Fractures : 



12. Skull in Mystriosuchus (Triassic). 



13. Oblique fracture in humerus of Hypacrosaurus and subperios- 



teal abscess. 



14. Simple fracture in rib of Dinosaur. 



15. Fracture (?) of tail, accompanied by osteomyelitis. 



Presence of Bacteria 



This arra}^ of fifteen pathological results is indeed a startling one. I 

 do not say that this is all the pathology of the Mesozoic, but it is all I 

 have seen or heard described, and serves merely as a basis for future 

 knowledge. This array of diseased members argues for a long preceding 

 history of pathology of which we are largely ignorant. The necroses and 

 arthritides argue for the presence of Mesozoic pathogenic bacteria of 

 N'arious types which are otherwise unknown, although bacteria have re- 

 cently been seen by me in an osteomyelitis from the American Permian. 



Nature of Evidence 



It Avill be more satisfactory to discuss briefly the evidence on which the 

 above classification is made : 



I. Arthritides: This is a group term used to define all pathological 

 results found in or around the joint surfaces of the limbs, vertebra^ and 

 skull. The lesions are the result of a great variety of diseases. 



1. Spondylitis deformans : This is a tj'pe of pathology found around 

 the articular surface of the vertebrae. It is the result of inflammation 

 in the vertebral ligaments, caused either by infection or injury. It ac- 

 companies Pott's disease (vertebral tuberculosis) and may cause a com- 

 plete rigidity of the spine. Coossified vertebrae are often indications of 

 this form of pathology. The united caudals of Diplodocus described by 

 Hatcher and Osborn are clearly examples of this type. Other coossified 

 vertebrae in the dinosaurs are due to different causes. Thus the coossi- 

 fied caudals of Brontosaurus mounted in the, Carnegie Museum is not 

 Spondylitis deformans, but osteomyelitis. Spondylitis deformans has a 

 curiously satisfactory geological history, being known in the Comauch- 

 ean. Cretaceous, Eocene, Miocene, abundantly in the Pleistocene, and 

 very common in the Recent epoch. 



2. Multiple arthritis (Rheumatoid) : This form of pathology, involv- 

 ing the great toe of a large Kansas Mosasaur, is the only fossil example 

 known to me. This is a sort of Mosasaurian gout or rheumatism which 

 must have caused the old fellow some inconvenience. 



3. Arthritis deformans : Only two examples of this form of pathology 

 are known to me, both accompanying other pathological lesions. The 

 articular surfaces are only slightly deformed. 



