Recognition of disease in antiquity is predicated on the uniformity of the character of disease over time. Although bone can manifest only a limited spectrum of reaction to any "insult," the pattern of skeletal involvement is often highly specific [1]. One such pattern-vertebral destruction with partial collapse, minimal reactive bone formation, but fusing affected adjacent vertebrae (producing a coalesced, acutely angulated vertebral appearance)-is highly specific for mycobacterial disease, such as tuberculosis [1, 2]. Observation of such a phenomena in a Pliocene macropod stimulated this analysis.

Fused proximal caudal macropod (kangaroo) vertebrae (Queensland F178989), discovered on the Chinchilla Rifle Range in southeastern Queensland, Australia, consisted of one partially collapsed vertebra. angulated 90 degrees in juxtaposition to a second and associated with extensive new bone formation. The first vertebra had an irregular spinal canal with several speculations and was fused with the subjacent two vertebrae. There was an oval-shaped, slightly expansile lytic lesion in the right transverse process of the third vertebra. Three-dimensional computed tomographic reconstruction (done by Southwoods Radiology, Youngstown, Ohio, and Carol Scott, St. Joseph Hospital, Warren, Ohio) revealed classic collapse and fusion with no significant new bone formation (Figure 1).

View larger version (111K): [in this window] [in a new window]   Figure 1. Three-dimensional reconstruction of computed tomographic images of affected vertebrae. The left and middle panels reveal reconstructed radiologic images. The image in the upper right panel is slightly oblique. The images in the center and the bottom right panels have been manipulated to remove overlapping structures. Draining sinuses are especially visible on the bottom right image. The vertebral pedicle and spinous processes have been removed to allow visualization of the posterior aspect of the vertebral body. General disorganization of bone with collapse, minimal new bone formation, and draing sinuses are notable.

Disruption of vertebral centra with subsequent angulation and fusion is characteristic of Mycobacterium tuberculosis in humans [1, 2] and of M. avium in macropods [1, 3, 4]. Trauma and osteoporotic compression fractures do not produce lytic lesions [1, 2]. Cancer produces lytic lesions but not fusion. Spondyloarthropathy produces vertebral fusion but not transverse process lytic lesions or vertebral collapse. Brucellosis and fungal disease (such as that caused by Blastomycosis species) can produce lytic lesions. but collapse with fusion has not been observed [2].

Thus, mycobacterial disease seems to be the most reasonable diagnosis. The earliest previous example [5] was in a 6000-year-old Egyptian mummy. Queensland F178989 substantially extends the antiquity of mycobacterial infection (existent in contemporary macropods) to 5 million years and seems to represent the earliest notation of this infection [1].