Amber is fossilized tree resin, and inclusions usually comprise terrestrial and, rarely, aquatic organisms. Marine fossils are extremely rare in Cretaceous and Cenozoic ambers. Here, we report a record of an ammonite with marine gastropods, intertidal isopods, and diverse terrestrial arthropods as syninclusions in mid-Cretaceous Burmese amber. We used X-ray–microcomputed tomography (CT) to obtain high-resolution 3D images of the ammonite, including its sutures, which are diagnostically important for ammonites. The ammonite is a juvenile Puzosia (Bhimaites) and provides supporting evidence for a Late Albian–Early Cenomanian age of the amber. There is a diverse assemblage (at least 40 individuals) of arthropods in this amber sample from both terrestrial and marine habitats, including Isopoda, Acari (mites), Araneae (spiders), Diplopoda (millipedes), and representatives of the insect orders Blattodea (cockroaches), Coleoptera (beetles), Diptera (true flies), and Hymenoptera (wasps). The incomplete preservation and lack of soft body of the ammonite and marine gastropods suggest that they were dead and underwent abrasion on the seashore before entombment. It is most likely that the resin fell to the beach from coastal trees, picking up terrestrial arthropods and beach shells and, exceptionally, surviving the high-energy beach environment to be preserved as amber. Our findings not only represent a record of an ammonite in amber but also provide insights into the taphonomy of amber and the paleoecology of Cretaceous amber forests. Significance Aquatic organisms are rarely found in amber, but when they occur they provide invaluable evidence for the better understanding of amber taphonomy and past ecosystems. We report an ammonite and several marine gastropods alongside a mixed assemblage of intertidal and terrestrial forest floor organisms in mid-Cretaceous Burmese amber. Our discovery indicates that the Burmese amber forest was living near a dynamic and shifting coastal environment. The ammonite also provides supporting evidence for the age of the amber, which is still debated, and represents a rare example of dating using fossils present inside the amber.

Insect faunas are extremely rare near the latest Cretaceous with a 24-million-year gap spanning from the early Campanian to the early Eocene. Here, we report a unique amber biota from the Upper Cretaceous (uppermost Campanian ~72.1 Ma) of Tilin, central Myanmar. The chemical composition of Tilin amber suggests a tree source among conifers, indicating that gymnosperms were still abundant in the latest Campanian equatorial forests. Eight orders and 12 families of insects have been found in Tilin amber so far, making it the latest known diverse insect assemblage in the Mesozoic. The presence of ants of the extant subfamilies Dolichoderinae and Ponerinae supports that tropical forests were the cradle for the diversification of crown-group ants, and suggests that the turnover from stem groups to crown groups had already begun at ~72.1 Ma. Tilin amber biota fills a critical insect faunal gap and provides a rare insight into the latest Campanian forest ecosystem.

A diverse insect assemblage of exceptionally preserved debris carriers is reported from Cretaceous Burmese, French, and Lebanese ambers.

Myrmeleontiformia are an ancient group of lacewing insects characterized by predatory larvae with unusual morphologies and behaviours. Mostly soil dwellers with a soft cuticle, their larvae fossilize only as amber inclusions, and thus their fossil record is remarkably sparse. Here, we document a disparate assemblage of myrmeleontiform larvae from the mid-Cretaceous amber (99 Ma) of Myanmar, evidence of a considerable diversification. Our cladistic analysis integrating extant and extinct taxa resolves the fossils as both stem- and crown-groups. Similarities between extinct and extant species permit inferences of larval ethology of the fossil species through statistical correlation analyses with high support, implying that morphological disparity matched behavioural diversity. An improved understanding of the evolutionary history of antlions and relatives supports the conclusion that hunting strategies, such as camouflage and fossoriality, were acquired early within the lineage.

Mantispoidea (Insecta, Neuroptera) are well-known for the hypermetamorphic larval development and for most adults having praying mantis-like raptorial forelegs. Currently, this superfamily comprises Berothidae (beaded lacewings) and three raptorial mantispoid families: Rhachiberothidae (thorny lacewings), Dipteromantispidae and Mantispidae (mantidflies or mantid lacewings). It includes about 530 extant species in 74 genera, and 143 extinct species in 97 genera from the Upper Triassic to the Miocene. Berothidae, well-known for some adults with scale-like setae on the female wings, currently includes 119 extant species in 26 genera, and 59 extinct species in 37 genera from the Upper Triassic to the Eocene. Rhachiberothidae represents the relictual group of Mantispoidea, comprising only 14 extant species across four genera, which are confined to the Afrotropical Region. However, the abundant fossil records (28 species and 21 genera), especially from the Cretaceous, highlight the past glory of this family. The Cretaceous dipteran-like family Dipteromantispidae, comprising ten species across nine genera, remains enigmatic in terms of its phylogenetic status. Mantispidae, the largest family within Mantispoidea, comprises approximately 395 extant species across 44 genera and 46 extinct species in 30 genera, ranging from the Lower Jurassic to the Miocene. This family is distinctive from other raptorial families for its highly mobile and variously elongated prothorax. Here, we describe several new genera and species from mid-Cretaceous Kachin amber, Myanmar: Three new species of Osmyloberotha Khramov, 2021 (O. dispersa sp. nov., O. chenzuyini Zhuo, Li & Liu sp. nov. and O. magnimaculata sp. nov.) in Berothidae, with a detailed redescription of O. simpla Khramov, 2021; two new genera and three new species (Paraberothinae: Paraberothoides longispina Li, Zhang & Liu gen. et sp. nov.; Subfamily unknown: Dicranoberotha zhangzhiqiae Zhuo, Li & Liu gen. et sp. nov., Dicranoberotha liumohanae Zhuo, Li & Liu gen. et sp. nov.) of Rhachiberothidae, three new species (Enigmadipteromantispa dilatata Li, Nakamine, Yamamoto & Liu sp. nov., Kurtodipteromantispa relicta Li, Nakamine, Yamamoto & Liu sp. nov. and Kurtodipteromantispa univenula sp. nov.) of Dipteromantispidae, as well as four new genera and five new species (Symphrasinae: Parvosymphrasites aploneura Li, Lin, Liu & Wang gen. et sp. nov. and Proplega evelynae Zhuo, Li & Liu gen. et sp. nov.; Subfamily unknown: Haplacantha robusta gen. et sp. nov., Haplacantha tenuis gen. et sp. nov. and Mesomantispoides felixoporcus gen. et sp. nov.) of Mantispidae. Sinuijumantispa So & Won, 2022, previously classified within Drepanicinae, is now recognized as a stem group of Mantispidae, which is possibly related to Mesomantispoides gen. nov. or Mesomantispinae. Our new findings offer crucial insights into the taxonomy, morphological diversity and evolution of Mantispoidea.

Chinese fossils reveal a Triassic insect radiation.