Abstract We reanalyse the global distribution of gullies in order to provide a set of observational constraints that models of gully formation must explain. We validate our results derived from the global data with four detailed case studies. We show that the availability of steep slopes is an essential factor to consider when assessing the spatial distribution and abundance of gullies. When the availability of steep slopes is taken into account, it reveals, with a few exceptions, that gullies are found almost uniformly across the whole 30°–90° latitude band. Our analysis also reveals that massive ice deposits are anti-correlated with gullies, and that the undulations in the equatorwards limits of the gully distribution could be explained by longitudinal variations in maximum surface temperatures (controlled by variations in surface properties, including thermal inertia and albedo). We find a sharp transition in both hemispheres between pole-facing gullies, which extend from 30° to 40°, to a more mixed, but dominantly equator-facing orientation of gullies polewards of 40°. We have no definitive explanation for this transition but, based on previous studies, we suggest it could be linked to the availability of near-surface ice deposits.

ABSTRACT Florissant fossil beds ranks among the best documented Cenozoic fossil deposits in the world in number of scientific publications and named species. The history of geoscience research on the Upper Eocene Florissant Formation spans nearly one and a half centuries. New excavations and transfers of historic collections have spread Florissant fossils to nearly 30 natural history museums during that period. The history of acquisition, conservation, and taxonomic study of each museum’s collection is unique, so Florissant collections provide examples of how taxonomic diversity, physical conservation, and public exhibition of collections vary with provenance. Dispersal of fossils among museums, including separation of type specimen parts and counterparts, has led to a variety of challenges for research on Florissant fossils. First, an exploratory, quantitative analysis of taxonomic diversity in four collections of fossil insects from Florissant uncovers a pattern of identification bias. Some taxonomists preferentially identify common taxa or consistently misidentify rare taxa, for instance. In light of this result, it is recommended that researchers vet any set of identifications made by multiple researchers or, ideally, identify specimens anew. Second, observations of Florissant specimens at different museums show that a large number of fossils have been lost, damaged, or destroyed due to actions such as travel on loan, display in exhibits, or application of non-archival conservation techniques. Through the digitization process, including cataloging and imaging specimens, curatorial staffs have discovered the extent of uncatalogued or missing material. Digitization has mitigated some of the challenges associated with dispersion of specimens. Collaborative projects across museums have led to rediscovery of lost specimens or discovery for the first time of parts and counterparts that correspond to the same fossil but are housed at different institutions. Online databases that serve specimen images allow researchers to assign new taxonomic determinations, controlling for bias from earlier researchers, or to examine fossils remotely from photographs, reducing the need to handle and ship fragile material for loans. Moreover, providing public access to museum specimen records through collaborative digitization projects expands the opportunities to exhibit and develop specimen-based educational curricula.

ABSTRACT Museum collections provide a tremendous wealth of data bearing on biogeography, the field that focuses on the study of the distribution of organisms in space and time. Biogeography is a discipline that played a fundamental role in the development of ideas on evolution in the nineteenth century, and it still is a vibrant research area today. One way that biogeography has remained vibrant is through the burgeoning area of biodiversity science. There are many aspects of biodiversity science relevant to paleontology, running the gamut from conservation paleobiology to ecosystem observations, etc. Our especial focus here is on biodiversity science approaches involving the analysis of museum specimen records using mapping and analytical approaches, such as the geographic information system (GIS) and ecological niche modeling (ENM), to quantify how climate change has caused (and will continue to cause) species to move across the face of the globe through time. Initial efforts considered extant taxa, but now analyses of extinct taxa are becoming more commonplace. These analyses of fossil taxa offer extensive opportunities to gain increased insight into biogeography and also macroevolution. This contribution focuses specifically on approaches using fossil taxa and their associated museum specimen data. Such approaches have shown how invasive species have contributed to ancient biodiversity crises, how species niches largely remain stable over geological time scales, how it is predominately abiotic factors, as opposed to competition, that influence species distributions and determine species survival in the long term, and finally how extant species that have been present in marine ecosystems for millions of years are now in grave peril due to impending climate changes projected to occur in the near term. Each of these discoveries will be highlighted in order to help show the value that museum collections of fossils continue to have in the twenty-first century.

Abstract Interpretation of sparse or incomplete datasets is a fundamental part of geology, particularly when building models of the subsurface. Available geological data are often remotely sensed (seismic data) or very limited in spatial extent (borehole data). Understanding how different datasets are interpreted and what makes an interpreter effective is critical if accurate geological models are to be created. A comparison of the interpretation outcome and techniques used by two cohorts interpreting different geological datasets of the same model, an inversion structure, was made. The first cohort consists of interpreters of the synthetic seismic image data in Bond et al. (‘What do you think this is?: “Conceptual uncertainty” in geoscience interpretation’, GSA Today , 2007, 17 , 4–10, http://dx.doi.org/10.1130/GSAT01711A.1 ); the second cohort is new and interpreted borehole data. The outcomes of the borehole interpretation dataset support earlier findings that technique use, specifically evidence of geological evolution thought processes, results in more effective interpretation. The results also show that the borehole interpreters were more effective at arriving at the correct interpretation. Analysis of their final interpretations in the context of psychological and medical image analysis research suggests that the clarity of the original dataset, the amount of noise and white space may play a role in interpretation outcome, through enforced geological reasoning during data interpretation.