Paradoxides jemtlandicus Wiman, 1903, from strata near the boundary between the oelandicus Stage and the paradoxissimus Stage of the middle Cambrian in central Sweden, is redescribed using more complete specimens than were known hitherto. It is one of the earliest species of the genus Paradoxides sensu stricto, and though the form of the dorsal exoskeleton and the transverse shape of the hypostome are normal for the genus, compared with typical Paradoxides such as P. paradoxissimus it shows features that can be regarded as primitive. These features include the shape of the glabella, the lack of strong fusion of the rostrum with the hypostome, the acute inner spine angle of the librigena and the short pygidium; they are reminiscent of some species of Hydrocephalus.

The Upper Ordovician Kyrkås Quartzite Formation at the Nifsåsen Quarry (Jämtland, Sweden) exhibits c. 90 m of siliciclastic sedimentary rocks deposited on a shallow shelf at the craton-attached part of the Caledonian foreland basin. Five lithologies are distinguished, including claystone, mudstone, siltstone, subarkose and sublitharenite. Based on these five lithologies, sedimentary structures and biota, three marine facies associations are defined: the Mudstone association (FA1) deposited close to storm wave base, the Sandstone/mudstone association (FA2) formed between storm and fair-weather wave bases, and the Sandstone association (FA3) accumulated above fair-weather wave base. The facies associations are arranged in two sequences, c. 50 and 40 m thick, separated by a transgressive surface, indicating repeated shoreline progradation. Both sequences commence with marine heterolithic shales and siltstones, with upwardly increasing frequency of tempestites. Continued shoaling is indicated by a dominance of hummocky and trough (locally tabular) cross-stratified sandstone beds in the upper part of each sequence. Sand beds are increasingly amalgamated up-sequence, reflecting progressively diminishing accommodation space. The depositional style and sedimentary structures indicate that the study area was storm-dominated with an abundant supply of siliciclastic material. Biostratigraphic data tie the depositional changes to the globally recognized Late Ordovician (Hirnantian) glacial interval. These data suggest that the first sequence was formed during the initial phase of regression in the earliest Hirnantian. The lowermost part of the overlying sequence contains elements of a typical Hirnantia fauna followed by beds yielding Normalograptus persculptus, suggesting a second regressive cycle in the Jämtland basin during the early N. persculptus Biozone.