Macroevolutionary dynamics along with the innovations of raptorial insect forelimbs

Evolutionary innovations are often identified as the drivers of adaptive radiations; however, not all innovations have such positive effects. Here we use the raptorial appendages of Mantispoidea, comprising ~530 species (Insecta, Neuroptera), as a case study in the evolution of a powerful predatory appendage, based on a detailed phylogeny and rich evidence of the raptorial appendages in modern and fossil forms, of which we present 14 new species based on exceptionally preserved fossils. We show a single origin of raptorial forelegs with key innovations triggering early adaptive radiation during the Late Triassic. However, after that, further evolution of the raptorial foreleg did not always promote lineage diversification. At times, it limited the morphological diversity of other body parts and led to lineage constraint by intense competition, e.g., in Rhachiberothidae. Conversely, in Mantispidae, reduced emphasis on the foreleg and increased modularity in other body parts to optimize predator-prey interactions and respond to environmental changes, accelerated diversification. Significant oscillations of diversification were also probably influenced by major environmental changes through the Mesozoic. Our results uncover the intricate evolutionary patterns and profound significance of raptorial specializations, providing insights into the role of innovations in shaping evolutionary trajectories.