Friday, 1 January 2021

EAGER FORMATION: TUZOIA

This specimen of the arthropod Tuzoia sp. is from the Lower Cambrian Eager Formation of British Columbia. 

Tuzoia is an extinct genus of large bivalved arthropod known from Early to Middle Cambrian marine environments in what is now the Burgess Shale, Emu Bay Shale, Kaili, the Rockslide Formation, the Spence Shale, Wheeler Formation, and Marjum Formation, and the Kinzers Formation. 

As you can see here, they are also known from the Lower Cambrian Eager Formation. This particular specimen is from the Rifle Range outcrop near Cranbrook where you can also find numerous fragments and complete specimens of the olenellid trilobites Ollenellus sp. and the larger, more robust Wanneria dunnae, along with Mesonacis eagerensis (Best, 1952).

The site outcrops at a few locations as you head east out of Cranbrook towards Fort Steele. The first trilobites were discovered with the building of the Kootenay Highway connecting Cranbrook to Fort Steele and beyond. Several other localities, including the outcrops at the Silhouette Rife Range — which is literally on a Rifle Range where folks go to shoot at things — is a shade older than the Middle Cambrian Burgess Shale but the fauna here is much less varied. 

The site has been known and collected since the 1920s. Back in the day, fossil collecting was a family affair with folks heading out in their lightly coloured finery to picnic and surface collect the eroding exposures. Cranbrook local, Clement Hungerford Pollen was an engineer and avocational palaeontologist. He promoted collecting the exposures of the Eager Formation around 1921. As a pedigreed Englishman of considerable means, he had invested in the Kootenay Central Railway, revitalizing the town by opening up railway access within the region.