Abstract The Stoer, Sleat and Torridon groups lie unconformably on Palaeoproterozoic Lewisian metamorphic rocks. They contain organic carbon microfossils claimed to be non-marine and to include eukaryotes. We consider the evidence for terrestrial interpretations from each formation of the Torridonian Supergroup. The range of sedimentary structures and the boron content of illite led us to the overall conclusion that, based on the currently available evidence, the Torridonian Supergroup was probably entirely non-marine. Evidence for terrestrial life in these rocks comes from microbially induced sedimentary structures, including wrinkle structures with reticulate and elephant skin fabrics. Organic remains and microscopic carbonaceous compressions mostly reported from phosphates in the grey shales of the Stoer, Aultbea and Applecross formations are dominated by sphaeromorph acritarchs. The Diabaig phosphatic lagerstätte includes three-dimensional preservation of eukaryotic and prokaryotic organisms, providing remarkable insights into non-marine life around 1 billion years ago. Supplementary material: Taxonomy of Torridon Group microfossils from thin sections of phosphatic material (adapted from Battison 2012) is available at https://doi.org/10.6084/m9.figshare.c.3522753

Abstract Complete metamorphosis evolved in insects towards the end of the Palaeozoic Era. A wide range of pupation strategies existed and numerous biosedimentary structures associated with these have been described. The fossil record of endogenous materials associated with pupation, e.g. cocoons, is more limited. Here we report six amber-coloured specimens from the earliest Cretaceous of southern England that were tentatively identified on collection as insect cocoons. These were analysed by Fourier transform infrared spectrometry, stereomicroscopy and X-ray microtomography to elucidate their origin. The interpretation of the Fourier transform infrared spectrometry data was inconclusive because the spectra showed some differences from those of amber. A seed pod origin seems likely for at least two of the objects based on their size, shape and the lineations on their surfaces. Three specimens are more cocoon-like based on their overall morphology and a fibrous surface texture. Although plant megaspore membranes have features analogous with these specimens and cannot be ruled out, the similarity to and variability found within insect cocoons, coupled with the range of potential insect architects present at the time of origin, make an insect origin more likely. We review a number of hymenopteran clades whose extant members construct comparable cocoons. The possible cocoons may have been resin-coated to protect the larva inside from predation, or they may have passively come into contact with resin prior to burial. Supplementary material: All TIFF computed tomography slices from the scan, the computed tomography log file, a surface model of the specimen and digital visualizations of both the whole specimen and the perforations are available at https://doi.org/10.6084/m9.figshare.c.3704794

Abstract Amber is known for its remarkably well-preserved fossils, but the chemical complexity of amber and its history are less well known. Amber is highly variable in both its physical and chemical properties, which are dependent on factors such as the source tree and the diagenetic history. Amber from a given locality therefore has a unique chemical composition. Fourier transform infrared (FTIR) spectroscopy is often used to determine the chemical composition of amber and to provide a fingerprint for amber samples. We used FTIR spectroscopy to analyse samples spanning the time period from the Early Cretaceous to the Oligo-Miocene from 17 localities in the Americas, Europe and Asia. We then used cluster analysis to examine the trends in amber chemistry and to increase our understanding of its formation through time. A detailed analysis of the clustering followed by modelling of the variables of importance suggested that the exocyclic methylene group content and conformation play a major part in explaining the clustering. Other variables, such as the ester and alkyl contents, contribute to identification. Placed in a broader perspective, our study indicates that the dominant factor in clustering is the age of the amber, followed by the locality. Supplementary material: Detailed sample list and combined spectra of all samples are available at https://doi.org/10.6084/m9.figshare.c.3704920

Abstract The Ediacara biota of the late Neoproterozoic is justly famous as a biological puzzle. Studies of Ediacaran biology have commonly used analogy with living organisms as a cipher for the decoding of biological affinity, and consequently the life mode and habit. Here, we discuss the problems of using such analogous reasoning and put forward our alternative approach, that of using Morphospace Analysis for the study of growth, form and phylogeny. This tool, we suggest, has the potential to be used for testing the unity of an evolutionary clade, such as ‘rangeomorphs’ and ‘dickinsoniomorphs’. Preliminary data from the members of the Ediacara biota do indeed show such a unity within our preliminary morphospace model (all k values are low). This method reveals no clear relationships, between these forms and more recent biological groups such as the sea pens or the Foraminifera.