Root traces in fossil bones from the Huayquerian (Late Miocene) faunal assemblage of Telén, La Pampa, Argentina

One of the exposures of the Cerro Azul Formation in northern La Pampa (Argentina) has yielded a Huayquerian (Upper Miocene) faunal assemblage. The degree of bioerosion caused by roots on mandibles of Paedotherium minor (Mammalia, Notoungulata, Hegetotheriidae) was analyzed, in an attempt to throw light upon the events that affected the remains after deposition. According to the features observed on the specimens, two types of traces were dentified. These were referred to the ethological categories Sphenoichnia and Corrosichnia. The first type is interpreted as the marks produced by rootlets growing on the skeletal element/sediment boundary after burial. These traces would indicate the development of a herbaceous cover on the soil where the remains were deposited and later buried and may be another feature helpful in the identification of these paleosols. The second type implies a surface dissolution of the hard substrate, which in this case is the fossil itself. The characteristics of the remains that show this kind of trace may suggest that root growth has affected them only in recent stages

Effectiveness of an mHealth intervention combining a smartphone app and smart band on body composition in an overweight and obese population: Randomized controlled trial (EVIDENT 3 study)

Background: Mobile health (mHealth) is currently among the supporting elements that may contribute to an improvement in health markers by helping people adopt healthier lifestyles. mHealth interventions have been widely reported to achieve greater weight loss than other approaches, but their effect on body composition remains unclear. Objective: This study aimed to assess the short-term (3 months) effectiveness of a mobile app and a smart band for losing weight and changing body composition in sedentary Spanish adults who are overweight or obese. Methods: A randomized controlled, multicenter clinical trial was conducted involving the participation of 440 subjects from primary care centers, with 231 subjects in the intervention group (IG; counselling with smartphone app and smart band) and 209 in the control group (CG; counselling only). Both groups were counselled about healthy diet and physical activity. For the 3-month intervention period, the IG was trained to use a smartphone app that involved self-monitoring and tailored feedback, as well as a smart band that recorded daily physical activity (Mi Band 2, Xiaomi). Body composition was measured using the InBody 230 bioimpedance device (InBody Co., Ltd), and physical activity was measured using the International Physical Activity Questionnaire. Results: The mHealth intervention produced a greater loss of body weight (–1.97 kg, 95% CI –2.39 to –1.54) relative to standard counselling at 3 months (–1.13 kg, 95% CI –1.56 to –0.69). Comparing groups, the IG achieved a weight loss of 0.84 kg more than the CG at 3 months. The IG showed a decrease in body fat mass (BFM; –1.84 kg, 95% CI –2.48 to –1.20), percentage of body fat (PBF; –1.22%, 95% CI –1.82% to 0.62%), and BMI (–0.77 kg/m2, 95% CI –0.96 to 0.57). No significant changes were observed in any of these parameters in men; among women, there was a significant decrease in BMI in the IG compared with the CG. When subjects were grouped according to baseline BMI, the overweight group experienced a change in BFM of –1.18 kg (95% CI –2.30 to –0.06) and BMI of –0.47 kg/m2 (95% CI –0.80 to –0.13), whereas the obese group only experienced a change in BMI of –0.53 kg/m2 (95% CI –0.86 to –0.19). When the data were analyzed according to physical activity, the moderate-vigorous physical activity group showed significant changes in BFM of –1.03 kg (95% CI –1.74 to –0.33), PBF of –0.76% (95% CI –1.32% to –0.20%), and BMI of –0.5 kg/m2 (95% CI –0.83 to –0.19). Conclusions: The results from this multicenter, randomized controlled clinical trial study show that compared with standard counselling alone, adding a self-reported app and a smart band obtained beneficial results in terms of weight loss and a reduction in BFM and PBF in female subjects with a BMI less than 30 kg/m2 and a moderate-vigorous physical activity level. Nevertheless, further studies are needed to ensure that this profile benefits more than others from this intervention and to investigate modifications of this intervention to achieve a global effect

Late Miocene capybaras from Argentina: Skull anatomy, taxonomy, evolution, and biochronology

Fossil capybaras are morphologically extremely varied, but previous studies have disagreed on whether this diversity reflects intraspecific variation or the existence of multiple species. Here, we review the capybaras from the classic Argentinian Late Miocene localities of Paraná River cliffs (“conglomerado osífero” of the Ituzaingó Formation, Entre Ríos), and Chillhué and Guatraché shallow lakes (Cerro Azul Formation, La Pampa), and perform a morphometric analysis of their upper cheek teeth and the posterior portion of the rostrum. Our results confirm that all of the specimens from the “conglomerado osífero” belong to the single species Cardiatherium paranense. In addition, we refer a specimen from Tupungato (Río de los Pozos Formation, Mendoza) to C. paranense, thus expanding its geographical range. The material from La Pampa represents a different taxon, and is here preliminary referred to Cardiatherium aff. orientalis. Our systematic interpretation of Late Miocene capybaras suggests that the early radiation of this group was not as explosive as previously thought, and was likely constrained by the early acquisition of large size, increasing complexity of the cheek teeth, and probably semi-aquatic habits

Coprolitos en la Formación Monte Hermoso (Mioceno tardío-Plioceno temprano), Farola Monte Hermoso, Buenos Aires, Argentina

Los bromatolitos forman parte de un grupo de trazas fósiles que incluye a los coprolitos o excrementos fósiles, las egagrópilas o regurgitaciones y los cololitos, es decir restos que contienen material retenido “in situ” dentro del tracto intestinal (Hunt et al., 1994). Al igual que otras trazas constituyen una evidencia directa del comportamiento de antiguos organismos, aportando información referida a paleodietas, diversidad de biotas y relaciones interespecíficas tales como predador-presa y parasitosis, entre otras (Pollard, 1990; Andrews y Fernández Jalvo, 1998; Chin, 2002; Duarte et al., 1999). Los coprolitos producidos por vertebrados son notablemente variables en composición, forma y tamaño, dependiendo de la masa corporal del productor, tipo de alimentación y condiciones de depositación, diagénesis y preservación a las que fueron sometidos. Estas características dificultan la asignación de los mismos a un productor en particular (Häntzschel et al., 1968; Pollard, 1990; Chin, 2002). En esta oportunidad se describen y analizan tres coprolitos, con material fósil muy fragmentario incluido en ellos, provenientes de los niveles inferiores de la Formación Monte Hermoso (Zavala, 1993). Sobre la base de sus características se definieron dos morfotipos distintos.Fil: Tomassini, Rodrigo Leandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Montalvo, Claudia Inés. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentin

Histotaphonomy of a Pleistocene megamammal assemblage from Argentine Pampas

This work involves a multy-proxy approach of taphonomic features of the extinct giant ground sloth Lestodon armatus (Xenarthra, Mylodontidae). The study is based on paleohistological, mineralogical, and geochemical analyses from the Late Pleistocene Playa del Barco site (Buenos Aires Province, Argentina). Transverse thin sections of ribs and vertebrae were studied under light microscope, polarizing petrographic microscope, and scanning electron microscope (SEM), combined with chemical analysis using energy dispersive spectroscopy (EDS) and micro-X-ray diffraction (μXRD). The internal crystalline structure and mineral composition remains almost unaltered. The bone microstructure is well preserved in all the samples, although it was affected by different types of microfractures and infillings. Numerous radial microcracks were identified in the secondary osteons of all specimens evidencing wet depositional environment. The mineralogical and geochemical composition of the infillings and encrustations indicates that the enrichment with new elements was due to direct exchange with the sediments in which they were buried. Mineralogical evidence from the infillings allows to identify different diagenetic pathways; most of the skeletal elements were quickly buried in the vadose zone, while others were buried in the phreatic zone, directly or after some time immersed in a continental aquatic context. The fossildiagenetic information obtained from the Lestodon armatus fossils provides novel information to interpret and reconstruct the whole taphonomic history and the environmental and climatic conditions that favored the preservation of the Playa del Barco fossil assemblage during the end of the Last Glacial Maximum.This work was supported by the Secretaría de Ciencia y Tecnología, Universidad Nacional del Sur, Argentina [PGI 24H/154], the Universidad Nacional de La Pampa, Argentina [21G], and the Ministerio de Ciencia e Innovación, Spain [PID 2021-126933NB-I00 and COOPB20589]. This study is framed in a postdoctoral grant awarded by CONICET Research Council of Argentina [2020-134-APN-DIR# CONICET] to DMM.Peer reviewe

Understanding the Impact of Trampling on Rodent Bones

International audienceExperiments based on the premise of uniformitarism are an effective tool to establish patterns of taphonomic processes acting either before, or after, burial. One process that has been extensively investigated experimentally is the impact of trampling to large mammal bones. Since trampling marks caused by sedimentary friction strongly mimic cut marks made by humans using stone tools during butchery, distinguishing the origin of such modifications is especially relevant to the study of human evolution. In contrast, damage resulting from trampling on small mammal fossil bones has received less attention, despite the fact that it may solve interesting problems relating to site formation processes. While it has been observed that the impact of compression depends on the type of substrate and dryness of the skeletal elements, the fragility of small mammal bones may imply that they will break as a response to compression. Here, we have undertaken a controlled experiment using material resistance compression equipment to simulate a preliminary experiment, previously devised by one of us, on human trampling of owl pellets. Our results demonstrate that different patterns of breakage can be distinguished under wet and dry conditions in mandibles, skulls and long bones that deform or break in a consistent way. Further, small compact bones almost always remain intact, resisting breakage under compression. The pattern obtained here was applied to a Pleistocene small mammal fossil assemblage from Wonderwerk Cave (South Africa). This collection showed unusually extensive breakage and skeletal element representation that could not be entirely explained by excavation procedures or digestion by the predator. We propose that trampling was a significant factor in small mammal bone destruction at Wonderwerk Cave, partly the product of trampling caused by the raptor that introduced the microfauna into the cave, as well as by hominins and other terrestrial animals that entered the cave and trampled pellets covering the cave floor. © 2022 by the authors. Licensee MDPI, Basel, Switzerland