First report of amber with spider webs and microbial inclusions from the earliest Cretaceous (c. 140 Ma) of Hastings, Sussex

摘要

Early Cretaceous amber resins with macroscopic inclusions are extremely rare, as are ambers with inclusions from the parent plant. Here, we report earliest Cretaceous amber resins found within alluvial soils of the Ashdown Formation near Hastings in Sussex. In contrast to younger Cretaceous examples, this Hastings amber was arguably deposited shortly before the emergence of the earliest flowering plant communities c. 140 Ma BP. Preliminary studies reveal plentiful organic inclusions, including vascular tissues, tracheid cells and putative resin ducts of the parent coniferous trees. We also report remarkably preserved soil microbes, including structures comparable with actinobacterial colonies, putative fungal or cyanobacterial filaments, and the earliest examples of spider silk webs. The last includes threads that are twisted, paired and coated with sticky fluid droplets, comparable with those of araneoid spider webs studied by us in modern cherry tree resins. Together, these Hastings amber inclusions became entombed within resins that seeped through the charred bark of coniferous trees subjected to severe fire damage, whose logs were then swept onto fluvial wetlands by floods. Embalming resins of this kind may have evolved to combat damage associated with insects, fungi and widespread forest fires.