Hard ticks in Burmese amber with Australasian affinities

Three examples of metastriate hard ticks (Ixodida: Ixodidae) with apparent affinities to modern Australasian genera are described from the mid-Cretaceous (ca. 100 Ma) Burmese amber of Myanmar. Two nymphs of Bothriocroton muelleri sp. nov. represent the oldest (and only) fossil record of this genus, living members of which are restricted to Australia and predominantly feed on monitor lizards, snakes and echidnas. A female of Archaeocroton kaufmani sp. nov. shares its basis capitulum shape with the tuatara tick Archaeocroton sphenodonti (Dumbleton, 1943), the only extant member of this genus and an endemic species for New Zealand. The presence of 2 Australasian genera in Burmese amber is consistent with a previous record of an Ixodes Latreille, 1795 tick from this deposit which resembles Australian members of this genus. They further support an emerging hypothesis that fauna of the amber forest, which may have been on an island at the time of deposition, was at least partly Gondwanan in origin. A revised evolutionary tree for Ixodida is presented compiling data from several new Burmese amber ticks described in the last few years

A Systematic Investigation Into the Control of Roughness on the Flow Properties of 3D-Printed Fractures

Heterogeneous fracture aperture distribution, dictated by surface roughness, mechanical rock and fracture properties, and effective stress, limits the predictive capabilities of many reservoir‐scale models that commonly assume smooth fracture walls. Numerous experimental studies have probed key hydromechanical responses in single fractures; however, many are constrained by difficulties associated with sample preparation and quantitative roughness characterisation. Here, we systematically examine the effect of roughness on fluid flow properties by 3D printing seven self‐affine fractures, each with controlled roughness distributions akin to those observed in nature. Photogrammetric microscopy was employed to validate the 3D topology of each printed fracture surface, enabling quantification using traditional roughness metrics, namely the Joint Roughness Coefficient (JRC). Core‐flooding experiments performed on each fracture across eight incremental confining pressure increases (11 to 25 bar), shows smoother fractures (JRC 7) show as much as a 219% permeability increase. Micro‐computed tomography imaging of the roughest fracture under varying effective stresses (5 to 13.8 bar), coupled with inspection into the degree of similarity between fracture closure behaviour in 3D‐printed and natural rock fractures, highlight the capabilities of 3D‐printed materials to act as useful analogues to natural rocks. Comparison of experimental data to existing empirical aperture‐permeability models demonstrates that fracture contact area is a better permeability predictor than roughness when the mechanical aperture is below ∼20 μm. Such findings are relevant for models incorporating the effects of heterogeneous aperture structures and applied stress to predict fracture flow in the deep subsurface