Digital proliferative osteitis due to stress fracture in an Eocene crocodilian

A pathological phalanx of an Eocene crocodile is described, macroscopically and microscopically examined, and compared with contralateral phalanx of the same individual and other specimens of extant Crocodylus niloticus. Both manual examination and computed tomography scan analysis on the specimen reveal a significant bone abnormality in shape which translates into a moderate bone growth, producing a bone callus that covers part of the medial third of the distal diaphysis. Near the affected area, a pathological sulcus was found in comparison with the other healthy phalanges. This set of features fits to a stress fracture with a proliferative osteitis around the primary lesion. These data are not only according to described bone pathologies of living reptiles but also with other described bone lesions in extinct reptiles. This is the first description of a pathological lesion in an Iberian Eocene crocodile.