Evidence for an earliest late carboniferous divergence time and the early larval ecology and diversification of major Holometabola lineages

Abstract

Four fossil taxa of earliest Holometabola recently were identified based on a variety of determinative evidence and assigned to a stem-group or a basal lineage within a modern order. One consequence of these new discoveries is that the divergence date between the Holometabola and its sister clade has been set earlier than previously thought on the basis of fossils or molecular phylogenetic evidence. This new date provides a minimal calibration date pegged to the Early Carboniferous-Late Carboniferous boundary, and approximates an absolute date of 318 million years. The four taxa provide new insights into the life habits, particularly feeding habits, of early holometabolan larvae. Additionally, they require an explanation of why there is an 80 million year lag between the origin and the taxonomic dominance of this profound developmental innovation in early terrestrial ecosystems. An earlier lead time is likely present for these earliest holometabolan fossils, which can be extrapolated conservatively to the Late Mississippian, 328 to 318 million years ago. Consequently, a focused investigation on earlier, Late Mississippian strata to search for ancestral holometabolan insects is imperative. © New York Entomological Society.