‘Mediterranean Province' hyoliths from the middle Cambrian and Upper Ordovician of Sweden

Abstract

Nine species of hyoliths are described based on material collected in Skåne, southern Sweden, during the first half of the last century. The material derives from the middle Cambrian (Cambrian provisional Series 3) Exsulans Limestone Bed at Almbacken east of Lund and the Upper Ordovician (Katian–Hirnantian) Lindegård Formation at Tommarp west of Simrishamn. The Almbacken assemblage consists of three taxa; Nephrotheca ruderalis Marek, 1989?, Buchavilites sp., and Orthothecid sp. 3. The Tommarp assemblage comprises Bactrotheca deleta Novák, 1891, Circotheca sp., Sololites sp., Orthothecid sp. 1 and 2, and one species of Quadrotheca Sysoev, 1958. Albeit small, the collections, altogether comprising some twenty specimens, have important paleobiogeographic implications for these metazoans. All hyoliths documented herein were formerly regarded as occurring solely in the ‘Mediterranean’ paleobiogeographic province, encompassing central and southwestern Europe, and North Africa. The material at hand reveals that the distribution of Buchavilites Marek, 1975, Circotheca Sysoev, 1958, Nephrotheca Marek, 1967, Quadrotheca, and Sololites Marek, 1967 is now extended to Baltica, further eroding the assumed strongly provincial nature of these organisms.

Keywords:

• Hyoliths
• ‘Mediterranean Province’
• Cambrian
• Ordovician
• Baltica
• Skåne
• Sweden

Acknowledgements

The Swedish Geological Survey (SGU) and Department of Palaeobiology, Uppsala University in Uppsala generously provided working facilities for JMM. MEE and PA thank the Swedish Research Council for funding their research. Niklas Axheimer, Kvidinge, kindly offered digital files of the Fågelsång map and the Cambrian stratigraphy for us to modify and use. Loren E. Babcock, Columbus, and Artem Kouchinsky, Stockholm, critically reviewed and improved the manuscript.