Martin Brasier's contribution to the palaeobiology of the Ediacaran–Cambrian transition

Martin Brasier's work spanned almost the entire geological column, but the origin of animals and the nature of the Cambrian explosion were areas of particular interest to him. Martin adopted a holistic approach to the study of these topics that considered the interplay between multiple geological and biological phenomena and he sought to interpret the fossil record within the broad context of geological, biogeochemical and ecological changes in the Earth system. Here we summarize Martin's main contributions to this area of research and assess the impact of his findings on the development of this field

John Salter and the Ediacara Fauna of the Longmyndian Supergroup

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 theLongmynd for our understanding of late Ediacaran palaeobiology. © Taylor and Francis Group, LLC

Deciphering pyritization-kerogenization gradient for fish soft-tissue preservation

LNNano (SEM)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)LNNano (SEM): Quanta-18363Processo FAPESP: 2012/18936-0Processo FAPESP: 2012/00202-0CNPq: 154062/2014-6Soft-tissue preservation provides palaeobiological information that is otherwise lost during fossilization. In Brazil, the Early Cretaceous Santana Formation contains fish with integument, muscles, connective tissues, and eyes that are still preserved. Our study revealed that soft-tissues were pyritized or kerogenized in different microfacies, which yielded distinct preservation fidelities. Indeed, new data provided the first record of pyritized vertebrate muscles and eyes. We propose that the different taphonomic pathways were controlled by distinct sedimentation rates in two different microfacies. Through this process, carcasses deposited in each of these microfacies underwent different residence times in sulphate-reduction and methanogenesis zones, thus yielding pyritized or kerogenized soft-tissues, and a similar process has previously been suggested in studies of a late Ediacaran lagerstatte

Depositional dynamics of a bituminous carbonate facies in a tectonically induced intra-platform basin: the Shibantan Member (Dengying Formation, Ediacaran Period)

The Ediacaran Shibantan Member (Dengying Formation, South China) is characterised by a black, laminated bituminous limestone facies with diverse Ediacara-type organisms and trace fossils. However, still little is known about the evolution of the Shibantan basin and its sedimentary dynamics. A detailed sedimentological characterisation revealed that the Shibantan Member was deposited on a carbonate ramp system linked to an intra-platform basin. Evaporitic dolomites of the Hamajing Member (representing sub- to supratidal inner ramp environments above fair weather wave base) are sharply overlain by black, laminated limestones of the lower Shibantan Member, representing a subtidal lower- to middle ramp environment close to the storm wave base. This facies-shift implies a sudden local deepening event, probably due to a tectonically induced increase in subsidence. The Shibantan basin was subsequently filled as evidenced by the gradual transition into dark wavy dolomites deposited in a subtidal middle-ramp environment (i.e. between storm- and fair weather wave bases) and, eventually, the upper Dengying Formation (i.e. the Baimatuo Member), which represents the same depositional environments as the Hamajing Member. Sedimentation in the Shibantan basin was highly dynamic as evidenced by a distinct slumping horizon and mass-flow deposits, partly possibly due to synsedimentary tectonic processes. A microbial mat associated biota which includes Ediacara-type fossils is restricted to the lower Shibantan Member. The close spatial relationship between allochthonous event deposits and autochthonous fossil associations in this setting implies that the event deposits were not only important for the preservation of fossils, but probably also for the supply of nutrients