The Burgess Shale Formation in the Canadian Rockies of British Columbia is world-famous for its abundance of soft-bodied fossils. Mt. Stephen is a classic fossil locality to the south of the best Burgess Shale quarries. The rocks of Mt. Stephen are also Burgess Shale Formation, but soft-bodied fossils are far less common. The most common fossils seen in rocks on the slopes of Mt. Stephen are decent-sized specimens of Ogygopsis klotzi trilobites. Disarticulated pygidia, cranidia, thoracic segments, and partially- to fully-articulated specimens are common in these rocks. The area is now a national park, but vintage specimens are sometimes available for examination.
The fossil shown below is an Ogygopsis tail + three thoracic segments. The larger slab of which this is a part has many other fossils, including additional Ogygopsis material, other polymeroid trilobites, orbiculoid brachiopods, and Selkirkia worm tubes.
Ogygopsis klotzi pygidium (tail) (2.1 cm across) in slightly calcareous mudshale. From the “Ogygopsis beds” of the Burgess Shale Formation on Mt. Stephen, British Columbia, southwestern Canada (vintage specimen).
Photo by Nicole Byrd.