Gelada Research Articles

Variation in Craniodental Pathologies Among Cercopithecoid Primates.

Pathologies of the skull and teeth are well documented for many human populations, but there are fewer studies of other primates. We contrast lesion prevalence and patterning among cercopithecoid primates and map variation onto socioecological variables. We compare craniodental lesions in six species: Nasalis larvatus (n = 54), Colobus polykomos (n = 64), Cercopithecus mitis (n = 65), Macaca fascicularis (n = 109), Theropithecus gelada (n = 13), and Papio anubis (n = 76). One of us (C.A.K.) evaluated each adult skull for multiple lesion types using standard criteria. We also tested for a relationship between lesion prevalence and cranial suture fusion (age proxy). We used nonparametric tests for sex and species differences as well as pathology co-occurrence in SPSS. Socioecological data come from previous studies. Sex differences in lesion prevalence were only detected in P. anubis. Within taxa, some lesion types co-occurred. In Macaca, the presence of caries was associated with several other lesion types. Pulp cavity exposure co-occurred with TMJ osteoarthritis in multiple taxa. Among taxa, male P. anubis had higher lesion prevalences, particularly related to the anterior dentition and facial trauma. Because we did not detect a relationship between suture fusion and lesion prevalence, we propose that craniodental lesions may also be influenced by socioecological variables such as group composition and ratio of fruit to leaves in the diet. Our findings suggest that pain from pulp cavity exposure and related dental infections may alter chewing biomechanics and contribute to onset of TMJ osteoarthritis in nonhuman primates, as seen in humans. Further, we suggest that higher lesion prevalence in male baboons is likely related to male-male competition. Skeletal lesion analysis provides useful insight into primate socioecology, particularly for rare or difficult-to-observe phenomena, and provides additional biological context for our own species.

Gelada genomes highlight events of gene flow, hybridisation and local adaptation that track past climatic changes.

Theropithecus gelada, the last surviving species of this genus, occupy a unique and highly specialised ecological niche in the Ethiopian highlands. A subdivision into three geographically defined populations (Northern, Central and Southern) has been tentatively proposed for this species on the basis of genetic analyses, but genomic data have been investigated only for two of these groups (Northern and Central). Here we combined newly generated whole genome sequences of individuals sampled from the population living south of the East Africa Great Rift Valley with available data from the other two gelada populations to reconstruct the evolutionary history of the species. Integrating genomic and paleoclimatic data we found that gene-flow across populations and with Papio species tracked past climate changes. The isolation and climatic conditions experienced by Southern geladas during the Holocene shaped local diversity and generated diet-related genomic signatures.

Bridging Species Divides: Affiliative Interactions between Theropithecus gelada and Papio anubis in an Unprotected Area in Ethiopia

Bridging Species Divides: Affiliative Interactions between Theropithecus gelada and Papio anubis in an Unprotected Area in Ethiopia

Cellular Redox Status of Dermal fibroblasts as a Model to Explore Hypoxia Responses Across Diverse Mammals

Specializations in energy production pathways can define phenotype in mammals, enabling resilience to environmental stressors and survival in extreme habitats. Most mammals rely on oxygen-based mitochondrial respiration to sustain high rates of ATP production necessary for homeothermy; oxidative phosphorylation is fueled by donation of reducing equivalents (NADH, FADH2) to the electron transport chain. As such, relative redox levels within the cell (NAD+/NADH ratio) indicate cell health and metabolic status. In hypoxic conditions, cells can experience reductive stress, evidenced by a buildup of NADH and altered NAD+/NADH ratio. We are using primary dermal fibroblasts isolated from skin biopsies in n=9 species to compare metabolic changes via the ratio between NAD+ and NADH when exposed to 0.5% O2 for 6-h and 24-h. Species were selected to encompass diverse phylogeny as well as to include species that are adapted to low oxygen environments (high altitude gelada baboons, diving humpback whales and Weddell seals). Control species without adaptation to hypoxic environments included human, dromedary camel, little brown bat, honey badger, and rhinoceros. We expect fibroblasts from species adapted to living with variable oxygen availability to have more stability in NAD+/ NADH ratios when exposed to hypoxia in cell culture compared to those from species that are not adapted to low oxygen environments. We quantified NAD+ and NADH following exposure to hypoxia as well as control normoxic samples. Preliminary data with n=3 biological replicates per species show that fibroblasts from the control animals display significant differences in NAD+/NADH ratio between normoxic and hypoxic treatments (Kruskal-Wallis test, p=0.01), however, there are no significant differences in the ratios presented for tolerant animals (Kruskal-Wallis test, p=0.518). This finding supports our hypothesis that animals adapted to low oxygen reduce variability in the NAD+/NADH ratios. Understanding the metabolic patterns when cells are exposed to reduced oxygen levels can provide a framework for estimating a species resilience to environmental variation. Funded by NSF #2022046, CSUN-OUR Summer Undergraduate Fellowship. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The sound of yawns makes geladas yawn

Yawning is undeniably contagious and hard to resist. Interestingly, in our species, even the mere sound of a yawn can trigger this contagious response, especially when the yawner is someone familiar. Together with humans, one other mammal species is known to produce loud and distinct vocalisations while yawning, Theropithecus gelada. Geladas are known for their complex social interactions and rich vocal communication, making them intriguing subjects for studying yawning behaviour. To explore the contagious effect of yawn sounds on geladas, we conducted playback experiments in a zoo-housed colony with animals living in two groups. We exposed them to yawn sounds (Test) or affiliative grunts (Control) produced by males from either their own group or the other one. The results were remarkable, as simply hearing yawn sounds led to yawn contagion in geladas, with multiple responses observed when the yawns came from members of their own group. This finding adds a significant contribution to the research on mimicry and behavioural contagion in primates. Moreover, it raises intriguing questions about the involvement of sensory modalities beyond visual perception in these phenomena.

Species Diversity, Abundance, and Habitat Association of Medium‐ and Large‐Sized Mammals in Harego Forest, South Wollo, Ethiopia

Despite the importance of the knowledge of mammals’ diversity, abundance, and habitat association for designing feasible conservation measures, most of the studies so far are emphasized in protected areas which in turn affects due understanding of the faunal records and conservation endeavors. Hence, we aimed to investigate species diversity, abundance, and habitat association of medium‐ and large‐sized mammals at Harego Forest, South Wollo, Ethiopia, from November 2020 to October 2021, covering both wet and dry seasons. We classified the study area into natural forest, bushland, and Erica woodland habitat types based on the topography and vegetation cover. The line transect technique was employed to study the diversity, abundance, and distribution of mammals. The counting of mammals was carried out along 16 transect lines from 06:00 to 10:00 h in the morning and from 15:00 to 18:00 h late in the afternoon when most animals are active in the study area. A total of 260 individual of medium‐ and large‐sized mammals belonging to 15 species, 10 families, and 5 orders were recorded. Among the recorded mammal species, Theropithecus gelada was the most abundant species while Felis serval was the least in the study area. The abundance of mammals varied significantly among the different habitat types. The highest and lowest mammalian species richness was recorded in the forest and Erica woodland habitats, respectively. The highest species similarity was observed between forest and bushland habitats. The study area is home to different species of mammals including the endemic mammals of Ethiopia that urges conservation stakeholders to design effective conservation measures to sustain the habitat and the mammalian species.

Diversity, abundance, and habitat utilization of medium and large-sized mammals in Debre-Libanos Monastery Forest, central part of Ethiopia

Abstract The present study aimed to estimate the diversity, abundance, and habitat utilization patterns of medium and large-sized mammals in the Debre-libanos Monastery forest, Ethiopia. The survey was conducted from December 2019 to October 2020, considering the wet and dry seasons. A stratified sampling design was applied, dividing the study area into four habitat types based on the vegetation composition and cover (i.e., Natural forest, Plantation, Cliff/Rocky, and Settlement). Both direct and indirect observations were used along the transect lines to identify mammal species. Indirect evidence included tracks, dens, droppings, hair, and other signs. Nineteen transect lines of 0.5‒1 km in length were established. The distance between transects was 200 m to avoid double counting. A total of 11 medium and large-sized mammal species belonging to 6 orders and eight families were identified during the study period. Carnivores and primates were the dominant orders, accounting for 36.4% and 27.3% of the species, respectively. Among primates, the Gelada baboon (Theropithecus gelada) is endemic to Ethiopia. The highest diversity of medium and large-sized mammals was observed in the natural forest during the dry season (Hʹ = 1.44), and the lowest diversity was recorded in the settlement during the dry season (Hʹ = 0.77). The abundance of different mammal species varied significantly from an even distribution (χ2 = 7344.9, df = 10, p < 0.001) and was not consistent among the four habitat types (Species × Habitat type interaction; Fisher-Freeeman-Halton exact test; χ2 = 649.3, df = 30, p < 0.001). High similarity in species composition was observed between the natural forest and plantation (SI = 0.94), whereas low similarity occurred between the cliff/rocky and settlement habitat types (SI = 0.18). Gelada baboon abundance was high; therefore, communities and government bodies must pay attention and conserve this species in the area.

Potential changes in the extent of suitable habitats for geladas (Theropithecus gelada) in the Anthropocene

BackgroundClimate change coupled with other anthropogenic pressures may affect the extent of suitable habitat for species and thus their distributions. This is particularly true for species occupying high-altitude habitats such as the gelada (Theropithecus gelada) of the Ethiopian highlands. To explore the impact of climate change on species distributions, Species Distribution Modelling (SDM) has been extensively used. Here we model the current and future extent of sutibale habitat for geladas. Our modelling was based on 285 presence locations of geladas, covering their complete current distribution. We used different techniques to generate pseudoabsence datasets, MaxEnt model complexities, and cut-off thresholds to map the potential distribution of gelada under current and future climates (2050 and 2070). We assembled maps from these techniques to produce a final composite map. We also evaluated the change in the topographic features of gelada over the past 200 years by comparing the topography in current and historical settings.ResultsAll model runs had high performances, AUC = 0.87–0.96. Under the current climate, the suitable habitat predicted with high certainty was 90,891 km2, but it decreased remarkably under future climates, -36% by 2050 and − 52% by 2070. However, since the habitats of geladas already extend to mountaintop grasslands, no remarkable range shifts across elevation gradients were predicted under future climates.ConclusionsOur findings indicated that climate change most likely results in a loss of suitable habitat for geladas, particularly south of the Rift Valley. Currently geladas are confined to higher altitudes and steep slopes compared to historical sightings, probably qualifying geladas as refugee species. The difference in topography is potentially associated with anthropogenic pressures that drove niche truncation to higher altitudes, undermining the climatic and topographic niche our models predicted. We recommend protecting the current habitats of geladas even when they are forecasted to become climatically unsuitable in the future, in particular for the population south of the Rift Valley.

Migration of a harem in search of a new leader following the loss of the former adult male leader from a one-male unit of geladas (Theropithecus gelada).

Geladas (Theropithecus gelada) live in social groups consisting of one-male units (sometimes referred to as "harems"), bands, and all-male units. Takeover by a new male affects the reproductive success and mating strategies of the individuals in a harem. However, to the best of my knowledge, there is no information available on the fate of the females in a one-male unit whose leader dies or disappears and is not replaced by another adult male. In 2017, I observed the migration of a male-less unit into the home range of my study group at Kosheme, in Wollo, Ethiopia. The unit consisted of 14 individuals. I observed the harem leader of my study group desert his unit and join the new unit, which appeared to peacefully accept him as their leader. These observations are in agreement with information from local residents, who told me that if the leader male of a unit dies, the male-less group (the "survivors") will soon migrate in search of a new adult male leader. To the best of my knowledge, this is the first documented case of the migration of a gelada harem in search of an adult male leader after the loss of the unit's former leader. This report contributes toward a better understanding of the reproductive behavior of geladas in particular, and of primates in general.

Behavioral activity and range patterns of the endemic Gelada monkey (Theropithecus gelada) in and around Jer Silase Monastery in North Shoa Zone, Ethiopia

Abstract The present study investigated the activity, range, and habitat utilization patterns of the Endemic Gelada Monkey (Theropithecus gelada) in and around Jer Silase Monastery in North Shoa Zone, Ethiopia. The study was conducted from January 2021 to October 2021 by considering the dry and wet seasons and stratifying the study area into natural forest, cliff/rocky, and farmland habitats. An instantaneous scan sampling method was employed to collect behavioral data. The activity patterns of three selected focal groups of Gelada monkeys were studied. GPS points of their predominant behavioral activities were recorded daily every 15 minutes from 7:00 to 18:00 for 12 days every month. A total of 5,592 individual activity records were obtained from 2312 scan samplings taken over 120 study days. Feeding comprised 54.52% of the activity time, followed by moving at 20.67% and socialization at 11.95%. A multivariate analysis of variance (MANOVA) revealed that the time allocated to different activity types varied significantly over the year with the month (Roy’s Largest Root = 2.7, F4,22 = 13.2, p < 0.001, partial η2 = 0.653). The longest mean monthly travel distance was 2817.61 ± 582.57 m, recorded at the Cliff/rocky habitat during the wet season. Gelada monkeys’ daily range length and home range size extended more in the dry season. These findings may be explained by reduced habitat quality associated with livestock grazing, agricultural expansion, and charcoal production. Therefore, appropriate conservation measures should be implemented to minimize such adverse effects and conserve the endemic Gelada Monkey.

Aggression rates increase around seasonally exploited resources in a primarily grass-eating primate

Abstract Female social relationships are often shaped by the distribution of dietary resources. Socioecological models predict that females should form strict linear dominance hierarchies when resources are clumped and exhibit more egalitarian social structures when resources are evenly distributed. While many frugivores and omnivores indeed exhibit dominance hierarchies accompanied by differential resource access, many folivores deviate from the expected pattern and display dominance hierarchies despite evenly distributed resources. Among these outliers, geladas (Theropithecus gelada) present a conspicuous puzzle; females exhibit aggressive competition and strict dominance hierarchies despite feeding primarily on non-monopolizable grasses. However, these grasses become scarce in the dry season and geladas supplement their diet with underground storage organs that require relatively extensive energy to extract. We tested whether female dominance hierarchies provide differential access to underground storage organs by assessing how rank, season, and feeding context affect aggression in geladas under long-term study in the Simien Mountains National Park, Ethiopia. We found that the likelihood of receiving aggression was highest when feeding belowground and that the inverse relationship between rank and aggression was the most extreme while feeding belowground in the dry season. These results suggest that aggression in geladas revolves around belowground foods, which may mean that underground storage organs are an energetically central dietary component (despite being consumed less frequently than grasses), or that even “fallback” foods can influence feeding competition and social relationships. Further work should assess whether aggression in this context is directly associated with high-ranking usurpation of belowground foods from lower-ranking females following extraction.

Assessing the recovery of Y chromosome microsatellites with population genomic data using Papio and Theropithecus genomes

Y chromosome markers can shed light on male-specific population dynamics but for many species no such markers have been discovered and are available yet, despite the potential for recovering Y-linked loci from available genome sequences. Here, we investigated how effective available bioinformatic tools are in recovering informative Y chromosome microsatellites from whole genome sequence data. In order to do so, we initially explored a large dataset of whole genome sequences comprising individuals at various coverages belonging to different species of baboons (genus: Papio) using Y chromosome references belonging to the same genus and more distantly related species (Macaca mulatta). We then further tested this approach by recovering Y-STRs from available Theropithecus gelada genomes using Papio and Macaca Y chromosome as reference sequences. Identified loci were validated in silico by a) comparing within-species relationships of Y chromosome lineages and b) genotyping male individuals in available pedigrees. Each STR was selected not to extend in its variable region beyond 100 base pairs, so that loci can be developed for PCR-based genotyping of non-invasive DNA samples. In addition to assembling a first set of Papio and Theropithecus Y-specific microsatellite markers, we released TYpeSTeR, an easy-to-use script to identify and genotype Y chromosome STRs using population genomic data which can be modulated according to available male reference genomes and genomic data, making it widely applicable across taxa.

The first large-scale record of gelada's spatial distribution and population size in Mountain chains of Tigray, Northern Ethiopia

Gelada (Theropithecus gelada) is an Ethiopian endemic mammal whose range was previously believed to be limited to the Bale and Simien Mountain national parks. However, knowledge of the range of the species is still not satisfactory. This study was designed to investigate the distribution and population size of the gelada in selected highlands in Tigray. To achieve this, study areas were divided into census tracts identified for a direct field assessment using habitat-based counting approaches. Moreover, informal interviews were conducted parallel to the direct field assessment in different villages. Our large spatial scale survey, the first of its kind for the region, confirmed the presence of T. gelada in three mountain clusters in Tigray for the first time. A total of 223 individual geladas were recorded in Ganta Afeshum, Hawzen and Welkait escarpments. The highest number of individuals (35.7 ± 3.8) was recorded in Hawzen (with 6.99 individuals/km2), followed by Ganta Afeshum (with 4.3 individuals/km2). Agricultural expansion, settlement and a lack of community awareness are the key threats operating against the conservation of the gelada in its current range in Tigray. Further research on the overall ecology, feeding, and spatial distribution of the species should be projected.

Best practices for genotype imputation from low-coverage sequencing data in natural populations.

Monitoring genetic diversity in wild populations is a central goal of ecological and evolutionary genetics and is critical for conservation biology. However, genetic studies of nonmodel organisms generally lack access to species-specific genotyping methods (e.g. array-based genotyping) and must instead use sequencing-based approaches. Although costs are decreasing, high-coverage whole-genome sequencing (WGS), which produces the highest confidence genotypes, remains expensive. More economical reduced representation sequencing approaches fail to capture much of the genome, which can hinder downstream inference. Low-coverage WGS combined with imputation using a high-confidence reference panel is a cost-effective alternative, but the accuracy of genotyping using low-coverage WGS and imputation in nonmodel populations is still largely uncharacterized. Here, we empirically tested the accuracy of low-coverage sequencing (0.1-10×) and imputation in two natural populations, one with a large (n = 741) reference panel, rhesus macaques (Macaca mulatta), and one with a smaller (n = 68) reference panel, gelada monkeys (Theropithecus gelada). Using samples sequenced to coverage as low as 0.5×, we could impute genotypes at >95% of the sites in the reference panel with high accuracy (median r2 ≥ 0.92). We show that low-coverage imputed genotypes can reliably calculate genetic relatedness and population structure. Based on these data, we also provide best practices and recommendations for researchers who wish to deploy this approach in other populations, with all code available on GitHub (https://github.com/mwatowich/LoCSI-for-non-model-species). Our results endorse accurate and effective genotype imputation from low-coverage sequencing, enabling the cost-effective generation of population-scale genetic datasets necessary for tackling many pressing challenges of wildlife conservation.

Vascularization underlies differences in sexually selected skin coloration in a wild primate.

Male reproductive competition can select for condition-dependent, conspicuous traits that signal some aspect of fighting ability and facilitate assessment of potential rivals. However, the underlying mechanisms that link the signal to a male's current condition are difficult to investigate in wild populations, often requiring invasive experimental manipulation. Here, we use digital photographs and chest skin samples to investigate the mechanisms of a visual signal used in male competition in a wild primate, the red chest patch in geladas (Theropithecus gelada). We analysed photographs collected during natural (n = 144) and anaesthetized conditions (n = 38) to understand variability in male and female chest redness, and we used chest skin biopsies (n = 38) to explore sex differences in gene expression. Male and female geladas showed similar average redness, but males exhibited a wider within-individual range in redness under natural conditions. These sex differences were also reflected at the molecular level, with 10.5% of genes exhibiting significant sex differences in expression. Subadult males exhibited intermediate gene expression patterns between adult males and females, pointing to mechanisms underlying the development of the red chest patch. We found that genes more highly expressed in males were associated with blood vessel development and maintenance but not with androgen or oestrogen activity. Together, our results suggest male gelada redness variability is driven by increased blood vessel branching in the chest skin, providing a potential link between male chest redness and current condition as increased blood circulation to exposed skin could lead to heat loss in the cold, high-altitude environment of geladas.

Infanticide by male gelada leader and group counterstrategies

AbstractInfanticide by males following the takeover and the acquisition of females with unweaned offspring has been observed in primate species. Like many other primate species, geladas (Theropithecus gelada) commit infanticide by nonsire males to enhance their reproductive success. Direct observation of infanticide is a rare phenomenon in geladas. During my stay in the field, I observed clear evidence of infanticide by nonsire male gelada. Adult females and juveniles of the group tried to stop the killing through scrambling, shouting, loudness, caustic and aggression. However, they could not save the infant's life. After they confirmed the death of the infant the group left the area. This direct observation confirms to provide reliable information on the occurrences of infanticide by male geladas in the wild. Such infanticide by nonsire male geladas most probably occurs to hasten mating receptivity in the females. Mass physical group defence strategy is counter adaptations to reduce the likelihood of infanticide by nonsire male geladas.

The earliest most complete skeleton of Theropithecus

The middle Pliocene site of Woranso-Mille in the Afar Region of Ethiopia has yielded numerous significant early hominin fossils representing multiple, coexisting taxa. Here we report on another significant discovery, the oldest partial skeleton of the papionin, Theropithecus. The specimen was recovered from the Aralee Issie collection area over multiple field seasons from 2004 through 2019. The specimen was unearthed in situ from the fluvial facies of the Mesgid Dora Tuff dated to 3.66–3.57 Ma. The partial skeleton, ARI-VP-1/26, is that of a subadult male lacking a skull. In the absence of unambiguously associated craniodental remains, the male status of the specimen was established from the dimensions of the long bones in comparison to those of other Theropithecus from Woranso-Mille. ARI-VP-1/26 is noteworthy because it preserves partial hand and foot skeletons, including a complete set of metacarpals from the left side. The theropith status of ARI-VP-1/26 was established based on the detailed anatomy of the postcranial skeleton, especially the proximal and distal humerus, proximal radius, and proximal femur. The morphology of the postcranium of ARI-VP-1/26 is consistent with that of recognized Theropithecus from Woranso-Mille and, specifically, with specimens recognized as Theropithecus oswaldi cf. darti from other sites. The ratio of the lengths of the first metacarpal to metacarpals 2–5 in ARI-VP-1/26 is intermediate between that seen in extant Papio and Theropithecus. In Theropithecus gelada and Theropithecus brumpti, the pairing of pollical and indical metacarpals of near equal length contributes to the species' high opposability index and is associated with a ‘manual grazing’ feeding habit. Cercopithecids constitute 43% of the identified vertebrates at Aralee Issie, and T. oswaldi cf. darti is the most common mammalian species. The monkeys of Aralee Issie lived in an open shrubland habitat, but the specific reasons for their high prevalence at the site are unclear.

Diet composition and diurnal activity patterns of gelada baboon (Theropithecus gelada)

AbstractGelada baboons (Theropithecus gelada) are the only surviving species of the genus Theropithecus and endemic to the highlands of Ethiopia. The present study deals with feeding ecology and diurnal activity patterns of gelada (T. gelada) in Wof‐Washa Forest, central Ethiopia. It was conducted from September 2016 to August 2017. Focal sampling technique for 10 min observation was employed to study the feeding ecology. Type of plant species consumed and parts eaten by gelada were recorded using binoculars during dry and wet seasons. On the other hand, data on diurnal activity patterns were collected using scan sampling technique. The activity patterns of bands under study were quantified by scanning at every 15‐min interval from 06:00 to 18:00 h. A total of 11 plant species that belong to 10 families were foraged by gelada during the wet and dry seasons. Grass was the main food source for geladas that contributed about 81% and 68% of their diet during the wet and dry seasons, respectively, while Thymus schimperi was the least consumed plant species during both wet (0.5%) and dry (1%) seasons. Grass blades were the most preferable food items by almost all age and sex categories. Daily activities of gelada were mainly dominated by feeding during both seasons. Geladas spent 58% of their time on foraging activity during the wet season and 67.2% of their time spent during the dry season. Geladas mainly depend on grasses for their diet in the study area. Therefore, to implement successful management and conservation of the species, the area needs to be properly protected.

The anatomy of the hindlimb of Theropithecus brumpti (Cercopithecidae, Papionini): Morphofunctional implications

Theropithecus brumpti is a primate known from numerous craniodental specimens in the Plio-Pleistocene Shungura Formation (Lower Omo Valley, Ethiopia), but the anatomy of its hindlimb is documented only by a few associated and mostly incomplete postcranial specimens. The adaptations of T. brumpti are still debated, with its substrate preferences and its use of squatting postures recently discussed based on anatomical differences when compared with its extant representative, Theropithecus gelada. Here, we describe an associated femur and tibia (L 869-1 and L 869-2) of a presumed T. brumpti male and a partial foot (L 865-1r and L 865-1t) of a male T. brumpti, dated to ca. 2.6 Ma and ca. 2.32 Ma respectively. Based on univariate and bivariate morphometric analyses, we provide new data on the morphological correlates of substrate preferences and postural behaviors of this fossil species. Our results are in agreement with previous analyses and present T. brumpti as a predominantly terrestrial primate. We demonstrate the presence of osteological correlates associated with the use of squatting behaviors in T. brumpti but also point to significant anatomical differences between this paleontological species and T. gelada. These differences blur the functional value of characters previously identified as diagnostic of T. gelada and its postural behavior. We further document the postcranial distinctiveness of the Theropithecus clade in relation to the Papio clade. This study thus provides new insights into the postcranial anatomy and paleoecology of an abundant fossil primate from the Plio-Pleistocene of eastern Africa.

Quantifying the movement, behaviour and environmental context of group-living animals using drones and computer vision.

Methods for collecting animal behaviour data in natural environments, such as direct observation and biologging, are typically limited in spatiotemporal resolution, the number of animals that can be observed and information about animals' social and physical environments. Video imagery can capture rich information about animals and their environments, but image-based approaches are often impractical due to the challenges of processing large and complex multi-image datasets and transforming resulting data, such as animals' locations, into geographical coordinates. We demonstrate a new system for studying behaviour in the wild that uses drone-recorded videos and computer vision approaches to automatically track the location and body posture of free-roaming animals in georeferenced coordinates with high spatiotemporal resolution embedded in contemporaneous 3D landscape models of the surrounding area. We provide two worked examples in which we apply this approach to videos of gelada monkeys and multiple species of group-living African ungulates. We demonstrate how to track multiple animals simultaneously, classify individuals by species and age-sex class, estimate individuals' body postures (poses) and extract environmental features, including topography of the landscape and animal trails. By quantifying animal movement and posture while reconstructing a detailed 3D model of the landscape, our approach opens the door to studying the sensory ecology and decision-making of animals within their natural physical and social environments.