EARLY HISTORY OF ARTHROPOD AND VASCULAR PLANT ASSOCIATIONS

Although research on modern plant-arthropod associations is one of the cornerstones of biodiversity studies, very little of that interest ha s percolated down to the fossil record. Much of this neglect is attrib utable to dismissal of Paleozoic plant-arthropod interactions as being dominated by detritivory, with substantive herbivory not emerging unt il the Mesozoic. Recent examination of associations from some of the e arliest terrestrial communities indicates that herbivory probably exte nds to the Early Devonian, in the form of spore feeding and piercing-a nd-sucking. External feeding on pinnule margins and the intimate and i ntricate association of galling are documented from the Middle and Lat e Pennsylvanian, respectively. During the Early Permian, the range of external foliage feeding extended to hole feeding and skeletonization and was characterized by the preferential targeting of certain seed pl ants. At the close of the Paleozoic, surface fluid feeding was establi shed, but there is inconclusive evidence for mutualistic relationships between insect pollinivores and seed plants. These data are gleaned f rom the largely separate trace-fossil records of gut contents, coproli tes, and plant damage and the body-fossil records of plant reproductiv e and vegetative structures, insect mouthparts, and ovipositors. While these discoveries accentuate the potential for identifying particular associations, the greatest theoretical demand is to establish the spe ctrum and level of intensity for the emergence of insect herbivory in a range of environments during the Pennsylvanian and Permian.