First discovery of Small Shelly Fossils and new occurrences of brachiopods and trilobites from the early Cambrian (Stage 4) of the Swedish Caledonides, Lapland

ABSTRACT New fossil discoveries are reported from the Grammajukku Formation at Luobákte south of Lake Torneträsk in northern Swedish Lapland, including a fauna of Small Shelly Fossils (SSF) from a limestone bed in the uppermost part of the formation and new occurrences of brachiopods and trilobites in siltstones of the lower part of the formation. The moderately diverse SSF fauna is the first of its kind reported from the Swedish Caledonides and includes the first record of the tommotiid Lapworthella schodackensis and the bradoriid spine Mongolitubulus spinosus from Baltica, together with fragmentary specimens of Bradoria sp. and remains of one additional bradoriid arthropod, a protoconodont and a helcionelloid mollusc. In addition, the limestone bed yields abundant specimens of the brachiopods Botsfordia cf. caelata and Eoobolus cf. priscus and an unidentified ellipsocephalid trilobite. Lower down in the Grammajukku Formation, specimens of both brachiopod taxa, orthothecid hyoliths, the trilobite Ellipsocephalus cf. gripi and an unidentified holmiid trilobite were found at several levels in a siltstone, previously regarded as unfossiliferous. These discoveries markedly increase the known diversity of the palaeobiota from the Grammajukku Formation in northern Lapland and provide new insights into the biostratigraphy and palaeoenvironment of the lower Cambrian in Scandinavia and the palaeobiogeography of Cambrian faunas in general.