John Salter and the Ediacara Fauna of the Longmyndian Supergroup

Abstract

John W. Salter's papers of 1856 and 1857 reported trace and body fossils from rocks of the Longmyndian Supergroup, Shropshire, that conventional wisdom had deemed literally “Azoic.” The significance of this work is reflected by its mention in On the Origin of Species, where it is cited as evidence for the existence of life prior to the Cambrian radiation. This study of Salter's historic specimens combined with recent field studies confirms that these structures likely represent microbial rather than metazoan markings. Nevertheless, this review confirms Salter as the unheralded founder of Precambrian palaeontology, many years before the existence of a Precambrian fossil record was widely known. This study also gives credit to a highly skilled palaeontologist, who appears to have struggled with psychological problems throughout his life. Salter had once been Adam Sedgwick's “youthful and cheerful companion” in the field, prior to embarking on an initially successful Geological Survey career. He was a widely renowned expert on Palaeozoic palaeontology, especially trilobites, but eventually fell into serious depression, which culminated in his suicide in 1869. Study and reinterpretation of his original materials reaffirms the importance of Salter's discoveries, and the Longmynd for our understanding of late Ediacaran palaeobiology.

Keywords:

• Ediacaran
• Longmyndian
• Palaeontology
• Trace fossil
• Microbial mats
• MISS

ACKNOWLEDGMENTS

This work has benefited from the support of Alex Liu and Liam Herringshaw. Dr. Len Hill provided invaluable help in tightening up the medical terminology. John Cope and Soren Jensen are thanked for their help, advice, and critical thoughts on an earlier version of the manuscript. The authors also acknowledge the support of staff at the National Trust at Carding Mill Valley, the British Geological Survey Palaeontology Unit, and the Oxford University Museum of Natural History. This work was completed during the doctoral research of R. Callow at Oxford University. R. Callow acknowledges the support of the Burdett-Coutts Fund (Oxford), the Isle of Man Department of Education and St Edmund Hall, Oxford. D. McIlroy acknowledges the financial support of the Canada Research Chairs Program and a NSERC Discovery grant. We thank Murray Gingras and two anonymous reviewers for comments that greatly improved the manuscript.