The first record of a Konservat‐Lagerstätten in which early post‐settlement stages of fossil archaeobalanids (Cirripedia: Balanomorpha) are preserved.

A diverse sessile barnacle fauna from a Miocene shallow‐water deposit at Dolnja Stara vas in Slovenia is described. It includes the first descriptions of early post settlement juveniles of Actinobalanus sloveniensis attached to mangrove leaves. These represent three distinct growth phases, the earliest being interpreted as being less than 24 h post settlement, the others being 1 to 2 days post settlement. An assessment of their taphonomy is provided. Associated adult balanomorphs are attached to a variety of organic substrates, including mangrove leaves and branches, fragments of the conifers ?Taxodioxylon, Carapoxylon, pine cones, molluscs, and cetacean bones. The barnacles include A. sloveniensis, Amphibalanus venustus, and Perforatus perforatus—many with opercula retained within the shells. A. venustus retains some of the original shell color. This is the second record of barnacle–plant associations from the Central Paratethys from Kamnik and Trbovlje. The paleoecology and paleogeography of the site are discussed. [ABSTRACT FROM AUTHOR]