Delving into the early Cambrian Cranbrook Lagerstätte of western Canada: an ichnologic analysis

New research from PhD candidate Alejandro Corrales-García, Gabriela Mángano and Jean Benard-Canon was just published on Burgess-shale type deposits from southeastern British Columbia.

A 2015 investigation of a 2.65 m interval recovered 12 ichnotaxa and three types of trace fossils left in open nomenclature, the most frequent including Helminthoidichnites tenuis, Palaeophycus tubularis, Diplocraterion isp., and finger-like structures (FLS). Overall, the Cranbrook assemblages do not present well-defined tiering structures and represent surficial epifauna and shallow-tier infauna that colonized the sea bottoms during brief windows between episodic flows and inhabited dysoxic to relatively well-oxygenated outer shelf environments. This study gives us additional insight into the behavior of soft-bodied organisms in some of the most recognizable deposits representing early animal life.

Figure 2. Trace fossils and physical sedimentary structures in the Diplocraterion isp. Ichnocoenosis. (1) General bedding-plane view of Bergaueria isp. (Be) and Diplocraterion isp. (Di) and close-ups of polished cross section showing typical claystone with thin intercalations of coarser grains in thin and discontinuous laminae displaying starved ripples and associated cross-lamination (yellow arrows), passively filled burrows (white arrow), and ruptured laminae of fine-grained sand (red arrows). (2) Bedding-plane view with close-up of Diplocraterion isp. with fine-grained sand fill. (3) Bedding-plane view displaying Diplocraterion isp. with fine-grained sand fill in incidental association with a Tuzoia carapace. Notice deformation of Tuzoia-bearing laminae by the overprinting burrow. (4) Bedding-plane view displaying stick-like individuals. Notice common individuals having slightly broader ends. All scale bars = 10 mm.

To learn more, check out the paper published in The Journal of Paleontology here.

Written by Zane Gabriel Goodell

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