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.

摘要

在瑞典拉普兰北部 Torneträsk 湖以南的罗巴克特的 Grammajukku 地层报告了新的化石发现，包括来自地层最上部石灰岩层的小型雪莱化石 (SSF) 动物群以及粉砂岩中新出现的腕足动物和三叶虫地层下部。适度多元化的SSF动物群的先河，从瑞典加里东报道，并包括托莫特壳类的第一条记录Lapworthella schodackensis和bradoriid脊柱Mongolitubulus刺从波罗的海，加上零碎的标本Bradoriasp. 以及另外一种短尾节肢动物、一种原牙形动物和一种螺旋形软体动物的遗骸。此外，石灰岩床产生丰富的腕足动物标本Botsfordia cf. caelata和Eoobolus参见。priscus和一种身份不明的椭圆头三叶虫。在 Grammajukku 组下方，腕足动物分类群、正足类动物标本、三叶虫Ellipsocephalus 的标本参见。格里皮并且在一块粉砂岩中的多个层面发现了一种身份不明的三叶虫三叶虫，以前被认为是无化石的。这些发现显着增加了拉普兰北部 Grammajukku 组古生物群的已知多样性，并为了解斯堪的纳维亚下寒武统的生物地层和古环境以及一般寒武纪动物群的古生物地理提供了新的见解。