PALEONTOLOGIC DEVIATES: TAPHONOMY VERSUS PATHOLOGY

If individual specimen pathology were studied for its own sake, its scientific value might not be sufficient to expend significant energies in distinguishing the effect of taphonomy. However, the field has extended to epidemiologic representation of disease and has allowed significant insights to ancient behaviors. Recent suggestions of extraordinary preservation also would have major implications for the field, once taphonomic influences have been discredited. If bridge is according to Hoyle, pathology is according to Doyle. Once you have eliminated the impossible, what remains, no matter how improbable, must be the standing hypothesis.

Macroscopic alterations: Mosasaur bones frequently illustrate grooves attributed to shark bites. Accompanying new bone formation allows at least some to be attributed to attacks on the living mosasaur. The process of recognition of the new bone formation in response to injury is similar to that for distinguishing articular joint erosions and periosteal reaction from taphonomic change.

Chemical: Protein (both structural and immunologic, DNA and isotope preservation are critical to study of phylogeny and of pathology. Tuberculosis was the first pathogen to be documented by actual identification of its DNA. This revised the entire paradigm related to its phylogeny and provides insight to Pleistocene extinction.

Radiologic: Bone density proved so subject to taphonomic influences as to be uninterpretable. However, x-rays can provide a surrogate for density information and provide hypothesis testing. Computerized tomography (CT) has application is specific areas to distinguish pathology and taphonomy. This is exemplified by apparent spearing of a mosasaur by a swordfish, which proved to be taphonomic collapse of the spinal process. Magnetic resonance imaging (MRI) proved feasible in fossils, as long as mobile protons were provided.

Pathology, and indeed organism preservation) will only be confidently recognized if we can confidently exclude taphonomic changes. They are the subject of this symposium.