Bromalites from the Cambrian (Series 2 and 3) of North Greenland

Abstract

Six assemblages of phosphatized bromalites from the Cambrian (Series 2 and 3) of North Greenland provide added insight into community structure in fossil assemblages otherwise dominated by microscopic skeletonized organisms. The bromalites, picked from acetic acid residues, display a wide range of morphologies, including pellets, segmented rods, wrinkled, smooth and segmented convoluted strings. Most are interpreted as extruded faecal material (coprolites) but moulds from the digestive tract (cololites) are also recognized. Most of the coprolites probably were produced by deposit-feeding invertebrates but rare specimens dominated by carapace fragments of bradoriid? arthropods are coprolites from predators. Zigzag-folded bromalites are interpreted as cololites of orthothecid hyoliths and are also recognized in inequivalent strata in China. Longitudinally wrinkled forms may be cololites of unknown origin. Minute spheres (Arenigiapella) forming one coprolite are interpreted as microcrystalline phosphatic coatings of bacteria. Post-diagenetic boring attributed to endolithic cyanobacteria is widespread.

Keywords::

• coprolites
• cololites
• bacteria
• endoliths
• Cambrian
• Greenland

Acknowledgements

Samples were collected during the North Greenland Project (1978–1980, 1984–1985) organized by the GGU. Scanning electron microscope facilities were provided by the Microscopy and Imaging unit, Evolutionary Biology Centre, Uppsala University; Miloš Bartol (Uppsala) carried out the Electron Dispersive Analysis. Reviews by Mats E. Eriksson (Lund) and an anonymous referee are gratefully acknowledged.