Life-restorations of ammonites and the challenges of taxonomic uniformitarianism

Ammonites were among the first life restorations of invertebrate fossil animals. These restorations appeared at around the same time (the 1830s)—and were executed by some of the same artists and scientists—as the earliest restorations of fossil vertebrates. As was the case for many of these vertebrates, ammonite restorations underwent major changes over the next century. These changes were associated with shifts in which living species were used as the basis for comparison with the extinct ammonites. The first models were argonauts (paper nautilus), because at the time they were better known than living Nautilus. By the mid-nineteenth century, Nautilus began to be used as a model, but with an ‘argonaut mode’ of life (floating on the surface). More modern-looking, subsurface restorations first appeared in the late nineteenth and early twentieth centuries. The issue of ‘taxonomic uniformitarianism’ remains a fundamental challenge for efforts to understand ammonite biology today, and this is reflected in the continuing variety of their restorations.