Early evolution of the weevils (Coleoptera: Curculionoidea): evidence from the Yixian Formation, China, and the Karatau site, Kazakhstan

The current classification of weevils (Curculionoidea), despite having witnessed numerous hypotheses, is still quite unstable at the higher levels and even more so at the lower levels. Although there is severe discordance among hypotheses of classification of extant weevils, this incongruence becomes more apparent when extinct groups are considered. Due to the lack of a robust morphological character system defining the major weevil clades, placement of fossil taxa has been difficult at best. According to the current understanding of the fossil record, weevils are believed to have diverged from their non-weevil ancestor sometime during the Middle to Late Jurassic. Many of the important fossils supporting these findings are from the Karatau site of South Kazakhstan, as well as the Yixian Formation in northeastern China. Weevils of these sites are under study here and represent the most primitive groups within the superfamily, such as Nemonychidae and Belidae. In addition to these families, the Karatau site also contains fossils of the extinct families Eobelidae, Obrieniidae, and Ulyanidae. Although their exact phylogenetic positions are still under examination, there appears to be a mixture of taxa representing some of the clades as they are defined today, as well as some mosaic taxa displaying characters suggestive of stem lineages.