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Annals of Medical History 



Arthritides are especially common in Pleis- 

 tocene mammals. The most prominent case 

 of a deformed joint is the case of two caudal 

 vertebrae (Fig. 14) of a large dinosaur, the 

 interarticular surfaces of which have been 

 extensively deformed and surrounded by a 

 huge exostosial growth. 



the middle of the tumor-like mass is 38.5 

 cm. The lesion has involved a length of 

 12 cm. Its surface generally is rather deeply 

 pitted. There is an unusual ventral growth, 

 which is shown in its normal condition in 

 Fig. 15 at "A." This bony process, "the 

 chevron," which served to protect the cau- 





Fig. 14 Two caudal vertebra? of a sauropodous dinosaur, possibly Apatosaurus, 

 exh biting a pathological lesion which may be interpreted as a haemangioma, 

 as a callus, as due to osteomyelitis or some unknown cause. This is one of the 

 most inte esting evidences of disease among fossil animals so far studied. A 

 detailed account of t will be given later. Other lesions of a similar nature are 

 fairly common among the dinosaurs of North America and Europe. One-half 

 natural size. The specimen is from the Como Beds, Comanchian, of Wyoming, 

 and is the property of the Kansas University Museum of Natural History. 



The mass resembles closely the tumor- 

 like masses seen on oak trees. It entirely 

 encircles the vertebrae and has involved 

 fully half of the two bones. The dark line 

 running vertically in the middle of Fig. 

 14 indicates the point where the normal 

 union of the two vertebrae would occur, 

 but all evidences of separate structures are 

 obliterated, and the two vertebrae are fused 

 into a single mass. The specimen has a 

 length of 26.5 cm. and a weight of 5.1 kg. 

 The circumference of the normal articular 

 surface of one of the vertebrae measures 

 27 cm., and the same measurement around 



dal vein and artery, is commonly present in 

 the tail of these reptiles. The growth of the 

 diseased portion is unequal and has in- 

 volved more of the vertebrae on one side 

 than on the other; likewise, the growth 

 has attained greater lateral dimensions on 

 one side. 



The enlargement, is somewhat suggestive 

 of the lesion of chronic osteomyelitis. It 

 may be a callous growth, possibly due to 

 a fracture of the caudal vertebrae; or it 

 may be a bone tumor. The character of the 

 lesion is naturally problematic, but it is 

 interesting that pathological growths in the 



