Description of a new type of trace fossils from nym­phs of mayflies (Ephemeroptera: Polymitarcidae) in bo­nes as Asthenopodichnium ossibiontum n. sp. The bones with the trace fossils occurred in sands and gravels of the Miocene (Badenian, Sarmatian and Pannonian) from northern Vienna Basin and from the Molassezone (Paratethys) of Lower Austria. The burrows are at first u-tubes with „Spreite“, but the preservation is in most of the cases a result of transport through water u-shaped notchs. The original environment of the producers of the trace fossils is a limnic biotop. It is suggested a warm-tempera­te climate for the Middle and Late Miocene in these latitudes.