Over the past two decades, the development of methods for visualizing and analysing specimens digitally, in three and even four dimensions, has transformed the study of living and fossil organisms. However, the initial promise that the widespread application of such methods would facilitate access to the underlying digital data has not been fully achieved. The underlying datasets for many published studies are not readily or freely available, introducing a barrier to verification and reproducibility, and the reuse of data. There is no current agreement or policy on the amount and type of data that should be made available alongside studies that use, and in some cases are wholly reliant on, digital morphology. Here, we propose a set of recommendations for minimum standards and additional best practice for three-dimensional digital data publication, and review the issues around data storage, management and accessibility.

2012. SPIERS and VAXML; A software toolkit for tomographic visualisation and a format for virtual specimen interchange. ABSTRACT'Virtual palaeontology', the study of fossils through the medium of digital models, is an increasingly important palaeontological technique. The vast majority of such work is tomographic, based around serial-slice datasets generated either physically or via scanning technologies. There are, however, no general-purpose software packages for tomographic reconstruction that are freely available and tuned to the needs of palaeontological data. In addition to its value in the primary study of specimens, virtual palaeontology has the potential to become a powerful medium for online data-dissemination, greatly increasing the degree to which palaeontologists are able to inspect each other's data. The absence of a standardised data-format for these datasets, however, has been a primary factor impeding such data exchange. We describe here solutions to both problems. The SPIERS software suite is a complete, free, multi-platform and fully documented software toolkit for the reconstruction of any tomographic data into threedimensional models. While capable of rapid reconstruction, it is especially well suited to the production of carefully prepared models from difficult data. We argue that virtualspecimen dissemination should take the form of triangle-mesh datasets, which can be generated from a maximally broad range of data sources. We introduce here the VAXML data format for such datasets, a candidate for a standard dissemination format for virtual specimens, both palaeontological and biological. The SPIERS suite includes a package capable of both visualising and exporting VAXML files, designed to support the viewing of complex datasets on relatively low-powered systems.

The evolutionary events during the Ediacaran-Cambrian transition (~541 Myr ago) are unparalleled in Earth history. The fossil record suggests that most extant animal phyla appeared in a geologically brief interval, with the oldest unequivocal bilaterian body fossils found in the Early Cambrian. Molecular clocks and biomarkers provide independent estimates for the timing of animal origins, and both suggest a cryptic Neoproterozoic history for Metazoa that extends considerably beyond the Cambrian fossil record. We report an assemblage of ichnofossils from Ediacaran-Cambrian siltstones in Brazil, alongside U-Pb radioisotopic dates that constrain the age of the oldest specimens to 555-542 Myr. X-ray microtomography reveals three-dimensionally preserved traces ranging from 50 to 600 μ m in diameter, indicative of small-bodied, meiofaunal tracemakers. Burrow morphologies suggest they were created by a nematoid-like organism that used undulating locomotion to move through the sediment. This assemblage demonstrates animal-sediment interactions in the latest Ediacaran period, and provides the oldest known fossil evidence for meiofaunal bilaterians. Our discovery highlights meiofaunal ichnofossils as a hitherto unexplored window for tracking animal evolution in deep time, and reveals that both meiofaunal and macrofaunal bilaterians began to explore infaunal niches during the late Ediacaran. NATuRE ECoLoGy & EvoLuTIoN Articles Nature ecology & evolutioNsupport for these suggestions is limited to purported body fossils of sponges 19 and demosponge biomarkers 20 . A considerable gap therefore remains between the fossil record of the late Ediacaran and molecular clock estimates for deep splits in the animal tree, for example the origin of Metazoa and Eumetazoa 3 . Assuming that contemporary molecular clock analyses yield accurate, if imprecise 18 , node ages for animal divergences, a small body size and concomitant limited fossilization potential 21 could reconcile these discordant records of animal evolution (but see ref. 22 ).The small body size of the ancestral bilaterian is supported by recent phylogenomic analyses of deep animal relationships, with acoel flatworms and xenoturbellids (Xenacoelomorpha) being a sister group to all remaining bilaterians (Nephrozoa) 23 , and smallbodied spiralian taxa (the 'Platyzoa') recognized as a paraphyletic grade with respect to macroscopic trochozoans 24 . This suggests that early bilaterians and spiralians were small bodied, possibly meiofaunal, and moved using ciliary gliding.Meiofauna comprises all organisms between 32 and 1,000 μ m in size that inhabit pore-water-rich sediments in freshwater to deepmarine environments 25 . Modern meiofaunal communities include animals, foraminifera and some ciliates, and contribute significantly to sediment bioturbation and bioirrigation 26,27 . The meiofauna can be divided into permanent members (that is, animals with organisms of a small size adapted and restricted to the meiofaunal, interstitial realm) and temporary meiofauna (for example, the ...