THE EARLIEST PALEOBIOLOGICAL INSIGHTS ON TRILOBITES

Trilobite fossils have fascinated humans since the Late Pleistocene. Eighteenth century and earlier trilobite literature is relatively meager, but ranges from brief remarks to lengthy, in-depth, illustrated monographs. The first known published figures date to the late 1690s. Before this, only three Chinese works and possibly one European work are known to mention trilobites, principally as curiosities. Initial academic investigations focused on the inferred living analogues of trilobites, and published conclusions range from molluscs to arthropods to vertebrates. The discovery of only isolated sclerites (heads and tails) or enrolled specimens in the 1710s to 1770s was the basis for several early misinterpretations. Once the complete trilobite body plan was widely understood, early naturalists were puzzled at the perceived paradox of an arthropodan segmented body having a molluscan-style hard shell. The lack of preserved appendages allowed some naturalists to accept a chiton-like affinity for trilobites. In the 1750s, structures such as the anterior cranidial border or thoracic pleurae were sometimes misidentified as antennae or walking appendages. The most in-depth early attempts at understanding trilobite fossils as once-living animals (in the 1770s to the 1840s) used various modern crustaceans as analogues. The discovery of living crinoids in the 1750s prompted an expectation that trilobites would eventually be found still alive in modern oceans. Although this anticipated breakthrough in understanding trilobite biology never arrived, by the mid-1840s naturalists appeared comfortable with using the anatomies and lifestyles of certain living crustaceans as the principal basis for interpreting trilobites. Species descriptions and naming became the principal focus of many studies starting about 1820. Soft-part reconstructions, ontogenetic studies, and stratigraphic occurrences were first published in the 1840s and 1850s. Usually only passing references to trilobite taphonomy and paleoecology are found in works of the 1700s and early 1800s.