The Eumetabola (Endopterygota (also known as Holometabola) plus Paraneoptera) have the highest number of species of any clade, and greatly contribute to animal species biodiversity. The palaeoecological circumstances that favoured their emergence and success remain an intriguing question. Recent molecular phylogenetic analyses have suggested a wide range of dates for the initial appearance of the Holometabola, from the Middle Devonian epoch (391 million years (Myr) ago) to the Late Pennsylvanian epoch (311 Myr ago), and Hemiptera (310 Myr ago). Palaeoenvironments greatly changed over these periods, with global cooling and increasing complexity of green forests. The Pennsylvanian-period crown-eumetabolan fossil record remains notably incomplete, particularly as several fossils have been erroneously considered to be stem Holometabola (Supplementary Information); the earliest definitive beetles are from the start of the Permian period. The emergence of the hymenopterids, sister group to other Holometabola, is dated between 350 and 309 Myr ago, incongruent with their current earliest record (Middle Triassic epoch). Here we describe five fossils--a Gzhelian-age stem coleopterid, a holometabolous larva of uncertain ordinal affinity, a stem hymenopterid, and early Hemiptera and Psocodea, all from the Moscovian age--and reveal a notable penecontemporaneous breadth of early eumetabolan insects. These discoveries are more congruent with current hypotheses of clade divergence. Eumetabola experienced episodes of diversification during the Bashkirian-Moscovian and the Kasimovian-Gzhelian ages. This cladogenetic activity is perhaps related to notable episodes of drying resulting from glaciations, leading to the eventual demise in Euramerica of coal-swamp ecosystems, evidenced by floral turnover during this interval. These ancient species were of very small size, living in the shadow of Palaeozoic-era 'giant' insects. Although these discoveries reveal unexpected Pennsylvanian eumetabolan diversity, the lineage radiated more successfully only after the mass extinctions at the end of the Permian period, giving rise to the familiar crown groups of their respective clades.

The molecular composition of 10 Cretaceous and one Eocene ambers from France was analyzed by infrared spectroscopy, solid-state (13)C nuclear magnetic resonance spectroscopy, and thermochemolysis gas chromatography-mass spectrometry. The terpenoids identified in the samples were used as biomarkers for the botanical origin of the resins. The Cretaceous samples, comprising the so-called Alpine, Anjou, Charentese, Provence, Pyrenean, and Vendean ambers, ranged from the Albian-Cenomanian transition to the early Santonian (100 to 85 Ma) and correspond to class Ib resins typical of conifers. The extinct conifer family Cheirolepidiaceae was proposed as the plant source of Pyrenean and brown Charentese ambers. Araucariaceae or Cheirolepidiaceae were the plant sources of the Cenomanian Alpine, Anjou, and yellow Charentese ambers. The Santonian ambers of Provence and Vendée were found to derive from the Cupressaceae. The Eocene Oise amber (ca. 53 Ma) is a class Ic resin typical of angiosperms and was produced by a Fabaceae. The evolution of resin sources from the early Cretaceous to the Eocene periods is discussed. Finally, a possible fingerprint hitherto unveiled is proposed for cheirolepidiaceous resins, defined by the simultaneous presence of phenolic diterpenoids, labdanoic acids, callitrisate structures, and their respective derivatives.

This paper overviews more than 39 families of fossil Coleoptera from Lower Cretaceous Lebanese amber from nine outcrops. Lebanese amber contains the oldest representatives of the families Scydmaenidae (considered by some as a subfamily of Staphylinidae), Ptiliidae, Elodophalmidae, Clambidae, Throscidae, Lebanophytidae fam. n., Ptilodactylidae, Cantharidae, Melyridae, Dasytidae, Dermestidae, Ptinidae, Kateretidae, Erotylidae, Latridiidae, Laemophloeidae, Salpingidae, Anthicidae, Melandryidae, Aderidae, Curculionidae (Scolytinae). The families Chelonariidae and Scraptiidae are known from both Lebanese amber and Baissa, with both sites having a comparable age. The subfamilies Trechinae (Carabidae), Euaesthetinae (Staphylinidae) and Liparochrinae (Hybosoridae) first appear in the fossil record in Lebanese amber. The Coleoptera in Lebanese amber mostly belong to groups with arboreal habits (as found today in wood and tree fungi).Eochelonarium bellegen. et sp. n.,Rhizophtoma synchrotronicasp. n.,Rhizobactron marinaegen et sp. n. andAtetrameropsis subglobosagen. et sp. n. are described from Lebanese amber. A new subfamily in the family Cerophytidae is proposed forAphytocerus communisZherichin, 1977 (Aphytocerinae subfam. n.) and new genusBaissopsisgen.nov. is erected forBaissophytum amplusChang, Kirejtshuk et Ren, 2011. Also a new interpretation of the taxon “Lasiosynidae” is provided by placing it as a subfamily in the family Eulichadidae with two genera (LasiosyneTan, Ren et Shih, 2007 andBupredactylaKirejtshuk, Chang, Ren et Shih, 2010), while the other genera initially regarded as “Lasiosynidae” were tentatively transferred into Eulichadinae sensu n. (MesodascillaMartynov, 1926;TarsomegamerusZhang, 2005;BrachysyneTan et Ren, 2009;AnacapitisYan, 2009;ParelateriformiusYan et Wang, 2010 andCretasyneYan, Wang et Zhang, 2013) with the new synonymy ofTarsomegamerusandParelateriformiussyn. n. The genusMesaplusHong, 1983 described in the family Triaplidae is also transvered to Eulichadinae. The generaArtematopoditesPonomarenko, 1990;DzeregiaPonomarenko, 1985 andGlaphyropteroidesHandlirsch, 1906 proposed for species known only by separate elytra and recently included in the “family” Lasiosynidae (Yan et al., 2013) are regarded as Elateriformiaincertae sedis. The first insect from the newly discovered outcrops of Nabaa Es-Sukkar – Brissa: Caza (District) Sir Ed-Danniyeh, Mouhafazet (Governorate) Loubnan Esh-Shimali (North Lebanon) is described and the first general description of this outcrop is made.