Growth rate, extinction and survival amongst late Cenozoic bivalves of the North Atlantic

ABSTRACT

Late Cenozoic bivalve extinction in the North Atlantic area has been attributed to environmental deterioration. Within scallops and oysters – groups with a high growth rate – certain taxa which grew exceptionally fast became extinct, while others which grew slower survived. Those which grew exceptionally fast would have obtained protection from predators thereby, so their extinction may have been due to the detrimental effect of environmental change on growth rate and ability to avoid predation, rather than environmental change per se. We investigated some glycymeridid and carditid bivalves – groups with a low growth rate – to see whether extinct forms grew faster than extant forms. Extinct Glycymeris subovata grew at about the same rate as the slowest-growing living glycymeridid and much slower than late Cenozoic examples of extant G. americana, which grew at about the same rate as the fastest-growing living glycymeridid. Extinct G. obovata and extinct Cardites squamulosa ampla also grew slower than G. americana. These findings indicate that within bivalve groups with a low growth rate, extinction or survival of taxa through the late Cenozoic was not influenced by whether they were relatively fast or slow growers. By implication, environmental change acted directly to cause extinctions in these groups.

KEYWORDS:

• Growth rate
• extinction
• Glycymeris
• Cardites
• late Cenozoic
• North Atlantic

Acknowledgments

We thank Lauck (‘Buck’) Ward for guiding ALAJ at field sites in the US and Patricia Kelley for donating a specimen from North Carolina; Bridget Kelly for permission to refer to unpublished information; Matt Riley for the loan of specimens from eastern England held at the Sedgwick Museum, Cambridge; Matt Hunt and Mark Dean for assistance in preparing material; Bernd Schöne for allowing use of the software Panopea; and the University of Derby for financial support of laboratory work and data analysis (URSS17-028 and URSS17-029). The comments of the two reviewers led to a significant improvement in the clarity, conciseness and scientific value of this paper, and we are very grateful for their contribution.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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Additional information

Funding

This work was supported by the University of Derby [URSS17-028,URSS17-029].