Abstract

The distribution and significance of lingulide brachiopods (Lingularia selwyni Whiteaves) and the trace fossil Lingulichnus in storm-generated, subtidal sandstone beds in the upper Toad and Liard formations of northeastern British Columbia is summarized. Storm-generated sandstone beds from two depositional environments (proximal offshore to offshore transition and lower shoreface) were analyzed. Lingulide material is present in only a small proportion of the storm-generated sandstone beds in the study interval. This distribution is interpreted to reflect the inherent patchiness of infaunal communities both in pre- and post-event communities. Middle Triassic lingulides, like their extant relatives, were capable of (1) surviving storm-induced burial by extending their burrows upward and reconnecting with the sediment-water interface; (2) surviving storm-induced exhumation and transport; and (3) reinhabiting the sediment and reestablishing themselves in new settings after relocation by storms. Depositional environment played a pivotal role in the likelihood that individual lingulides survived storm events. Lingulide faunas deposited in the proximal offshore to offshore transition experienced up to 15%–25% mortality during storm events with most storm survivors (90%–95%) able to reestablish themselves in feeding position at the sediment-water interface. Lingulide faunas deposited in lower shoreface settings experienced considerably higher mortality, with ∼60%–75% of the animals dying prior to the end of the storm and a further ∼45% surviving the storm events but failing to reestablish themselves at the sediment-water interface in life position. Escape burrowing and reburrowing following exhumation, entrainment, and transport are fundamental adaptations for infauna occupying such dynamic depositional settings as the subtidal littoral zone (neritic zone). This ability was likely integral in the long-term success of lingulides in Phanerozoic marine successions.

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