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Sequence stratigraphy and palaeontology of the upper Miocene Pisco Formation along the western side of the lower Ica Valley (Ica Desert, Peru)
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RBINS Staff Publications 2017
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Serial population extinctions in a small mammal indicate Late Pleistocene ecosystem instability
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The Late Pleistocene global extinction of many terrestrial mammal species has been a subject of intensive scientific study for over a century, yet the relative contributions of environmental changes and the global expansion of humans remain unresolved. A defining component of these extinctions is a bias toward large species, with the majority of small-mammal taxa apparently surviving into the present. Here, we investigate the population-level history of a key tundra-specialist small mammal, the collared lemming (Dicrostonyx torquatus), to explore whether events during the Late Pleistocene had a discernible effect beyond the large mammal fauna. Using ancient DNA techniques to sample across three sites in North-West Europe, we observe a dramatic reduction in genetic diversity in this species over the last 50,000 y. We further identify a series of extinction-recolonization events, indicating a previously unrecognized instability in Late Pleistocene small-mammal populations, which we link with climatic fluctuations. Our results reveal climate-associated, repeated regional extinctions in a keystone prey species across the Late Pleistocene, a pattern likely to have had an impact on the wider steppe-tundra community, and one that is concordant with environmental change as a major force in structuring Late Pleistocene biodiversity.
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RBINS Staff Publications
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Seven new species and two new genera of Physocypria sensu latu (Crustacea, Ostracoda) from Brazilian floodplains
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We describe seven new species in two new genera of the Physocypria sensu latu clade (Cyclocypridinae) from three of the main Brazilian floodplains. Brasilocypria pea gen. et spec. nov. and Brasilocypria ricardopintoi gen. et spec. nov. occur in the Upper Paraná River floodplain and the South Matogrossense Pantanal, Claudecypria mesquitai gen. et spec. nov., Brasilocypria alisonae gen. et spec. nov. and Claudecypria rochei gen. et spec. nov. were found in the South Matogrossense Pantanal, and Brasilocypria lordi gen. et spec. nov. and Brasilocypria namiotkoi gen. et spec. nov. occur in the Amazon River floodplain. All new species here described were found as sexual populations. Generally, they have a short and suboval carapace, with the left valve overlapping the right valve on all sides, except for the dorsal side in some species. The morphology of the hemipenis and the prehensile palps, together with the shape of the valves, were the most important characters to distinguish the species. Size differences between species can be substantial. Several characters, such as the absence in all new species of the short accompanying seta of the five natatory setae on the antenna; the presence in all new species of a long seta next to the two a-setae on the first thoracopod, and the presence/absence or differences in length of specific setae on the second and third thoracopod, are relevant for the generic diagnoses. We also redefine Keysercypria Karanovic, 2011.
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RBINS Staff Publications 2023
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Seven new species and two new subspecies of Sclerocypris SARS, 1924 from Africa, with new records of some other Megalocypridinis (Crustacea, Ostracoda)
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RBINS Staff Publications
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Seven new species of Trichodorus (Diphtherophorina, Trichodoridae) from Spain, an apparent centre of speciation.
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Sex determination using the Probabilistic Sex Diagnosis (DSP: Diagnose Sexuelle Probabiliste) tool in a virtual environment.
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The hip bone is one of the most reliable indicators of sex in the human body due to the fact it is the most dimorphic bone. Probabilistic Sex Diagnosis (DSP: Diagnose Sexuelle Probabiliste) developed by Murail et al., in 2005, is a sex determination method based on a worldwide hip bone metrical database. Sex is determined by comparing specific measurements taken from each specimen using sliding callipers and computing the probability of specimens being female or male. In forensic science it is sometimes not possible to sex a body due to corpse decay or injury. Skeletalization and dissection of a body is a laborious process and desecrates the body. There were two aims to this study. The first aim was to examine the accuracy of the DSP method in comparison with a current visual sexing method on sex determination. A further aim was to see if it was possible to virtually utilise the DSP method on both the hip bone and the pelvic girdle in order to utilise this method for forensic sciences. For the first part of the study, forty-nine dry hip bones of unknown sex were obtained from the Body Donation Programme of the Universite´ Libre de Bruxelles (ULB). A comparison was made between DSP analysis and visual sexing on dry bone by two researchers. CT scans of bones were then analysed to obtain three-dimensional (3D) virtual models and the method of DSP was analysed virtually by importing the models into a customised software programme called lhpFusionBox which was developed at ULB. The software enables DSP distances to be measured via virtually-palpated bony landmarks. There was found to be 100% agreement of sex between the manual and virtual DSP method. The second part of the study aimed to further validate the method by analysing thirty-nine supplementary pelvic girdles of known sex blind. There was found to be a 100% accuracy rate further demonstrating that the virtual DSP method is robust. Statistically significant differences were found in the identification of sex between researchers in the visual sexing method although both researchers identified the same sex in all cases in the manual and virtual DSP methods for both the hip bones and pelvic girdles.
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RBINS Staff Publications
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Sex in space! The importance of reproductive modes in astrobiology
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RBINS Staff Publications
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Sex in the city: uncovering sex-specific management of equine resources from prehistoric times to the modern period in France
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Sex identification from fragmentary archeozoological assemblages is particularly challenging in the Equid family, including for horses, donkeys and their hybrids. This limitation has precluded in-depth investigations of sex-ratio variation in various temporal, geographic and social contexts. Recently, shallow DNA sequencing has offered an economical solution to equine sex determination, even in environments where DNA preservation conditions is not optimal. In this study, we applied state-of-the-art methods in ancient DNA-based equine sex determination to 897 osseous remains in order to assess whether equal proportions of males and females could be found in a range of archeological contexts in France. We found Magdalenian horse hunt not focused on isolated bachelors, and Upper Paleolithic habitats and natural traps equally balancing sex ratios. In contrast, Iron Age sacrificial rituals appeared to have been preferentially oriented to male horses and this practice extended into the Roman Period. During Antiquity, the Middle Ages and the Modern Period, cities emerged as environments largely dominated by horse males. This strong sex-bias was considerably reduced, and sometimes even absent, in various rural contexts. Combined with previous archaeozoological work and textual evidence, our results portray an urban economy fueled by adult, often old, males, and rural environments where females and subadults of both sexes were maintained to sustain production demands.
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RBINS Staff Publications 2022
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Sex ratio bias caused by endosymbiont infection in the dwarf spider Oedothorax retusus
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RBINS Staff Publications
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Sexing the bony labyrinth: A morphometric investigation in a subadult and adult Belgian identified sample
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In forensic anthropology, sex estimation is a fundamental step in assessing individual biological profiles when analyzing human skeletons. Yet, current methods are not reliable enough to allow an accurate sex identification of highly fragmented, burnt, or subadult remains. This paper aims to investigate sexual dimorphism of the bony labyrinth on both identified subadult and adult individuals. The bony labyrinth is of particular interest for sex estimation since it is alleged to complete size and maturation pre-pubertally and is located inside the petrous part of the temporal bone which protects it from taphonomic processes. The study was performed on 93 CT scans of identified individuals from two Belgian osteological collections (19-20th century) and from current pediatric images (Erasme hospital, Brussels). Linear and angular measurements were taken on 2D slices of right bony labyrinths. Intra- and interobservers error measurements were calculated. Statistical tests were used to unravel any morphological variations between subadult and adult bony labyrinths and to highlight differences between females and males, separately in subadults and adults. Linear discriminant functions were established by cross-validation and tested on an independent sample from Belgium. Some measurements were significantly different between subadults and adults, and between females and males within both subadult and adult samples. Univariate functions achieved 72.7% in subadults and 68.4% in adults whereas multivariate equations increased accuracy respectively up to 84.9% and 78.4%. This study entails promising results to design a sex estimation method suitable for fragmented and/or subadult remains. Further metric approaches are needed to explore bony labyrinth sexual dimorphism.
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RBINS Staff Publications 2021 OA
