 |
| Proceratopyge rectispinata |
Trilobites, as you no doubt already know, are extinct marine arthropods that lived in Earth’s oceans for over 270 million years, first appearing in the Early Cambrian and disappearing at the end of the Permian.
They are named for their three-lobed, segmented exoskeleton, which is divided lengthwise into a central axis and two pleural lobes.
The Upper Cambrian strata of the McKay Group near Cranbrook, southeastern British Columbia, preserve a modest but scientifically important assemblage of trilobites that record life along the western margin of Laurentia roughly 497–485 million years ago.
During this interval, the region lay beneath a warm, shallow epicontinental sea, where fine-grained siliciclastic sediments accumulated on a broad continental shelf.
The trilobite faunas from the McKay Group are dominated by polymerid trilobites typical of Upper Cambrian shelf environments, including representatives of the families Pterocephaliidae and Elviniidae, with taxa comparable to Pterocephalia, Elvinia, and allied genera documented elsewhere in the Cordilleran margin.
They are characterised by well-developed cephalic borders, pronounced glabellar furrows, and reduced or effaced pygidia—morphological features commonly associated with soft-substrate, low-energy settings.
Preservation is generally as disarticulated sclerites—isolated cephala, thoracic segments, and pygidia—suggesting post-mortem transport or periodic storm reworking on the Cambrian seafloor.
As a guest of Chris New and Chris Jenkins (and collecting with great friends from the VIPS & VanPS) I have gleefully explored these Upper Cambrian exposures.
Most of my earlier travels in the area focused on the Lower Cambrian Eager Formation, and it was only in the early 2000s that I first explored the bounty nearby.
The McKay group offers a tantalizing selection of fauna and vastly different preservation than what we find in the Eager Formation.
Much of my collecting benefited from natural erosion, leaving the fossils sitting pretty on the surface. Excavation did yield some finds, including my best specimen of all my trips. I'll find that lovely and share a photo with all of you.
The assemblage provides valuable biostratigraphic control, allowing correlation of the McKay Group with coeval Upper Cambrian successions in the western United States and other parts of British Columbia.
A huge thank you to Dan Bowden and Chris Jenkins (who are both deeply awesome) for their help with the ID! Appreciate you two!
