The Spence Shale Lagerstatte: an important window into Cambrian biodiversity

The Spence Shale Member of the Langston Formation is a Cambrian (Miaolingian: Wuliuan) Lagerstatte in northeastern Utah and southeastern Idaho. It is older than the morewell-known Wheeler and Marjum Lagerstatten from western Utah, and the Burgess Shale from Canada. The Spence Shale shares several species with these younger deposits, yet it also contains a remarkable number of unique species. Because of its relatively broad geographical distribution, and the variety of palaeoenvironments and taphonomy, the fossil composition and likelihood of recovering weakly skeletonized (or soft-bodied) taxa varies across localities. The Spence Shale is widely acknowledged not only for its soft-bodied taxa, but also for its abundant trilobites and hyoliths. Recent discoveries from the Spence Shale include problematic taxa and provide insights about the nature of palaeoenvironmental and taphonomic variation between different localities.