Crossed tracks: Mesolimulus, Archaeopteryx, and the nature of fossils

摘要

Organisms leave a variety of traces in the fossil record. Among these traces, vertebrate and invertebrate paleontologists conventionally recognize a distinction between the remains of an organism's phenotype (body fossils) and the remains of an organism's life activities (trace fossils). The same convention recognizes body fossils as biological structures and trace fossils as geological objects. This convention explains some curious practices in the classification, as with the distinction between taxa for trace fossils and for tracemakers. I consider the distinction between parallel taxonomies, or parataxonomies, which privileges some kinds of fossil taxa as natural and others as artificial. The motivations for and consequences of this practice are inconsistent. By comparison, I examine an alternative system of classification used by paleobotanists that regards all fossil taxa as artificially split. While this system has the potential to inflate the number of taxa with which paleontologists work, the system offers greater consistency than conventional practices. Weighing the strengths and weaknesses of each system, I recommend that paleontologists should adopt the paleobotanical system more broadly.