324 R. L. MOODIE OUR KNOWLEDGE OF MESOZOIC PATHOLOGY 



II. Tiimoi'S : These pathological growths, neoplasms, are not due to a 

 definite infection and arise from preexisting tissues. Only two examples 

 of tumors are known during the Mesozoic. 



4. Osteoma: Seen on the dorsal vertebra? of a Kansas Cretaceous 

 Mosasaur. Not to be confused with a hypapophysis, but is a true out- 

 growtli of tlie vertebra. 



5. Hai'mangioma : Tliis has been previously described and appears to 

 be a true tumor. It occurs between two caudal vertebra? of a Comanch- 

 ean Dinosaur. 



III. Necroses : These are the definite result of hacterial or other infec- 

 tion. The various types can not be distinguished in a fossil condition. 

 There are numerous examples known. 



6. Necrosis with hyperplasia is present in the ilium of Camptosaurus 

 in the U. S. National Museum and in a Mosasaur radius belonging to 

 the University of Kansas. 



7. Caries is not common among fossil vertebrates, although Dollo 

 gives an example of it in the mosasaurs, and Leidy and Hermann have 

 described it in the American mastodon. I have never seen an example 

 of fossil dental caries. 



IV. Hyperostoses: These are thickenings of bone, taking the form of 

 outgrowths not classified in the preceding groups. 



8. Alveolar osteitis, the result of pyorrhea, I have never seen in Meso- 

 zoic fossils, although Dollo has described it in a Cretaceous Mosasaur. 



9. Exostoses are fairly common and assume a variety of forms. 



10. The pathology of Gigantism, or extreme osseous hyperplasia, is 

 suggested by Yolz and Abel as an explanation of certain hypertrophied 

 Nothosaur and fish bones. 



11. Osteoperiostitis: This is a diagnosis assigned as the cause of the 

 pathological excrescences seen in a Cretaceous Mosasaur from Kansas. 



V. Fractures are of a variety of types, depending on the situation and 

 the degree of pathology involved. 



12. Skull fracture in the Triassic Mystriosuchus reported by von 

 Huene. Occurs immediately anterior to the nares. 



1.3. Oblique fracture with subperiosteal abscess seen in the humerus 

 of Hypacrosaurus in the American Museum. A common form of pathol- 

 ogy today. The bridge of bone present in the fossil humerus is due to 

 an elevation of the periosteum by an enormous abscess capable of hold- 

 ing several liters of fluid. 



14. Simple fracture, commonest type of fracture among fossil animals. 

 An example in the mounted skeleton of Apatosaurus in Field Museum. 



1.5. Fracture in tail of Rrontosnurus with osteomyelitis. 



