In 1937, the Swedish palynologist Gunnar Erdtman (1897–1973) mounted two adapted vacuum cleaners atop an ocean-going liner and set out to obtain air samples as he crossed the Atlantic Ocean. The devices were able to capture samples of airborne pollen which were related to air volume and distance from land. The results of this investigation are still cited in the scientific literature, but a study of publications demonstrates that the ocean study had land-based antecedents. Furthermore, archival investigation reveals the background to such studies, including the technical plans for Erdtman’s ‘aerosol collector’, records of raw data from the voyage, draft portions of the key publication, photographs and the precise location of the land-based equipment. A storage loft in the Swedish Museum of Natural History in Stockholm has been found to house a surviving aerosol collector.

Ctenodactylid rodents prospered during the Paleogene in East and Central Asia, and due to their high diversification, they are important for biostratigraphic correlations. Here, we present new and diverse material from the late early Oligocene Nanpoping mammal fauna of the Lower Member of the Xianshuihe Formation from the Lanzhou Basin, Central China. Nine species – Tataromysplicidens, Tataromys sigmodon, Tataromys minor, Yindirtemys ulantatalensis, Yindirtemys shevyrevae, Alashania tengkoliensis, Karakoromys decessus, ?Euryodontomys ampliatus and Helanshania deserta – were recognized and described here in detail, the latter five species for the first time from early Oligocene Nanpoping fauna of the Lanzhou Basin. For the Lanzhou Basin, ctenodactylids show the maximum richness in the early Oligocene and have a comparatively high diversity compared with other contemporaneous faunas until the abrupt decline at the late Oligocene, with only Yindirtemys left. Ctenodactylid diversification in the early Oligocene may be related to the semi-arid climate with episodes of higher precipitation, and the following niche partitioning.