The earliest evidence for the alouattine clade, howler monkeys, can be found at the Middle Miocene site of La Venta in Huila Department, Colombia. La Venta has yielded over 100 vertebrate species including 12 primates representing all extant platyrrhine families and is notable as the site that provides the earliest evidence of a proto-Amazonian primate community. Currently, two alouattine species have been described: Stirtonia victoriae and Stirtonia tatacoensis. Stirtonia victoriae is found in the older La Victoria Formation and was previously known only from maxillary and cranial fragments. Stirtonia tatacoensis has been recovered from sediments in the younger Villavieja Formation and is primarily known from isolated teeth and partial mandibular remains. Here, we report the first mandibular specimens of S. victoriae, which preserve canines, premolars, and molars as well as the mandibular symphysis and portions of the mandibular ramus. We use three-dimensional geometric morphometric (3DGM) analysis of second lower molars to reconstruct diet as well as 3DGM analysis of mandibular shape to examine S. victoriae morphology within the evolutionary context of the platyrrhine radiation. Our dental analyses indicate that S. victoriae likely consumed leaves as a substantial portion of its diet. Its mandibular shape is broadly similar to that observed among atelids and howler monkeys, genus Alouatta, more specifically. Body mass reconstruction using lower first molar area and a phylogenetic least squares regression approach indicate that S. victoriae was around 6.6–8.7 kg. New body mass estimates using this method are also provided for other extinct platyrrhine species. The fossil evidence of S. victoriae described here provides the earliest example of committed leaf-eating among platyrrhines.

Cebus malitiosus Elliot, 1909 occurs along the north-eastern slopes of the Sierra Nevada de Santa Marta, Magdalena, Colombia. The species was described from material collected by Herbert H. Smith on 27 October 1898 near Bonda, at the northwestern base of the Sierra Nevada. The holotype is in the American Museum of Natural History, New York, accession number AMNH 14620. During a review of gracile capuchin monkey specimens, we found that the holotype of C. malitiosus is composed of two individuals: one the skin of a female and the other a skull of a male. Three other specimens collected on the same day have similar mismatches in their labelling, with two also having specimens from different individuals. Here we comment on the diagnosis of C. malitiosus since the original description assigned two individuals as the species' holotype. Based on J. A. Allen's report on H. H. Smith's expedition, which indicates that specimen AMNH 14620 was a male, we recommend retaining the skull as the holotype and removing the female skin from the type series.

Plasmodium malariae is a neglected human malaria parasite that causes persistent, often asymptomatic infections and remains difficult to diagnose. Despite being generally associated with lower prevalence and severity than other malaria parasites, P. malariae represents a significant public health concern, particularly in Africa, but also as a zoonosis in South America with monkey-adapted Plasmodium brasilianum. Plasmodium malariae and P. brasilianum population genetic structure, evolutionary history, and adaptive potential remain poorly understood, largely due to the historical scarcity of whole-genome data. By screening 226 monkey samples from two Latin American countries, we identified 20 Plasmodium-positives across multiple primate species, highlighting the persistence of this parasite in sylvatic transmission cycles. We also investigated the evolutionary history and genetic diversity of P. malariae using whole-genome sequencing data. By combining 79 newly sequenced genomes with 248 publicly available genomes, we analyzed a filtered dataset comprising 179 P. malariae, two P. brasilianum, and two P. malariae-like genomes. Population structure analyses revealed the presence of two genetically distinct but recombining clusters across African P. malariae populations. These clusters occur across multiple African countries at varying frequencies, without clear geographic segregation. Genome-wide scans of genetic differentiation and selection further identified numerous cluster-specific signatures of adaptation, including loci putatively involved in interactions with human hosts and mosquito vectors. Our results provide the first evidence for fine-scale population substructure within African P. malariae and reveal ongoing adaptive processes that may contribute to its persistence and transmission. By uncovering previously unrecognized genetic diversity and selection patterns, this study highlights the importance of population genomic approaches for understanding the evolutionary dynamics of this neglected malaria parasite.

Leucism is a hereditary genetic trait characterized by total or partial body hypopigmentation. This condition has been described across several taxa but is rarely observed in mammals. The environmental factors influencing the distribution of leucism and their impacts on the survival and fitness of individuals are still poorly understood. We present reports retrieved from peer-reviewed articles and fieldwork studies, according to the adaptive relevance of this condition in each species and the potential influence of environments under leucism. The reported number of leucistic primates has recently been increasing, likely due to citizen science and the widespread use of smartphones. We identified 23 records of leucistic primates, from at least eight different species and hybrids, related especially to forested biomes of South America. Given its contribution to understanding the ecology of these variations, we highlight the importance of a collaborative effort between the scientific community and the general public to report new cases of polymorphic phenotypes discovered in nature. Also, information on exact geographic coordinates is essential for the reports to be scientifically relevant. Our database can serve as a baseline for better understanding the spatial patterns of leucism in Neotropical primates and to comprehend the evolutionary ecology of genetically controlled polymorphic phenotypes and their persistence in wild populations.

Reconstructing ecological interactions within extinct vertebrate communities remains challenging, particularly for taxa such as South American native ungulates (SANUs) and caviomorph rodents that lack modern analogs. The Middle Miocene site of La Venta in Colombia hosts one of the most diverse tropical vertebrate assemblages in South America, but little is known about the paleocological interactions of its taxa. We present stable isotope (δ13C and δ18O) analyses of fossil tooth enamel from SANUs (n = 51) and caviomorph rodents (n = 16) to reconstruct paleodiet and niche partitioning. Minimal diagenetic alteration was confirmed using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy. All taxa exhibited C₃-dominated diets, consistent with forested tropical environments. However, inter-taxon isotopic variation revealed ecological differentiation: Miocochilius anomopodus (a typothere notoungulate) showed the narrowest niche breadth and highest δ13C values, suggesting occupation of more open habitats, while astrapotheres, toxodont notoungulates, and litopterns displayed broader niches indicative of closed-canopy forest browsing. The two rodent taxa showed distinct δ13C values despite morphological similarities, supporting niche differentiation within sympatric caviomorphs. These results provide the first isotope-based evidence for resource partitioning among Middle Miocene neotropical herbivores from Colombia and support paleoenvironmental reconstructions of La Venta as a heterogeneous mosaic of mainly forested areas with open habitats adjacent to large water bodies that hosted some of the largest vertebrates during the Miocene in South America.

Cryptic species are genetically distinct but morphologically similar lineages, frequently found in geographically complex regions where mountains and rivers serve as isolating barriers. In American primates, such as night monkeys (Aotus), cryptic speciation has been proposed but remains poorly understood due to limited sampling. In northwestern South America, members of the Aotus lemurinus complex (A. griseimembra, A. lemurinus, and A. zonalis) have been assumed to occupy distinct elevations, although no clear geographic boundaries have been identified. To clarify their evolutionary relationships, we integrated mitochondrial DNA data from 93 sites, ecological niche modeling, and analyses of hair length variation. Phylogenetic analyses recovered four major clades—one cis-Andean and three trans-Andean—showing strong geographic structure largely associated with the Magdalena River. Riverine barriers, rather than elevation, appear to have played a primary role in lineage divergence. Ecological niche modeling revealed potential distributions on opposite riversides across a broad elevational gradient, with a narrow zone of potential sympatry in the lower section of the Magdalena River. Niche similarity tests indicated no significant ecological divergence between clades. Hair length increased with elevation in wild populations inhabiting the Colombian Andes, on opposite sides of the Magdalena River, suggesting convergent morphological responses to highland ecosystems. These findings challenge previous taxonomic hypotheses that separated A. griseimembra and A. lemurinus by elevation and instead emphasize the role of riverine isolation—particularly along the upper and middle sections of the Magdalena River—in shaping the diversification of Aotus in northwestern South America.

Malaria in Latin America is largely caused by Plasmodium vivax, but the closely related monkey parasite Plasmodium simium has recently been observed in humans, thus raising new public health concerns. By screening 719 monkey samples from five Latin America countries, we identified 23 Plasmodium-positives. However, only four samples yielded sufficient mitochondrial DNA sequencing data to allow reliable species identification, and their inclusion in genome-wide population analyses. Using whole-genome variation data from these samples together with whole genome variations of 19 P. simium and 405 P. vivax isolates, we investigated their evolutionary history and population genetics. P. vivax, typically restricted to humans, was identified in three Colombian and one Brazilian monkeys, suggesting possible host niche expansion. Genetic analyses reveal recent genetic exchanges between both species and indicate that P. simium originated from a host jump approximately one to two centuries ago. Also other alternatives are possible, this host shift may have followed P. vivax migration from Central/North America to Brazil. Genome-wide scans revealed signals of positive selection in P. simium genes implicated in interactions with primate hosts, including PvRBP2a and PvRBP1b, as well as genes involved in interactions with mosquito vectors, such as PvCMRP1, PvPAT, and Pvs47. These findings shed light on P. simium evolutionary history. They also underscore the zoonotic risks, and the need to include monkeys in malaria prevention measures while ensuring human-wildlife coexistence.

Sloths (Mammalia, Xenarthra, Folivora) are one of the most diverse clades of mammals that can be found in the Middle Miocene assemblage of La Venta site (Laventan South American Land Mammal Age, SALMA; ca.13.5-11.8 Ma), in central Colombia. Here, we provide a description of a new a ground sloth, Megatherioidea gen. et sp. indet. from La Venta site, represented by a partial maxilla with teeth that exhibit shared characteristics with other sloths found in the Early Miocene (Santacrucian SALMA; ca. 18-16 Ma) from Argentina: Schismotherium, Pelecyodon, Hyperleptus, Hapalops, and Analcimorphus. The new specimen likely represents a new taxon, however additional and more complete material is necessary to properly evaluate this taxonomic hypothesis. We consider the specimen to be important due to its possible links with other sloth lineages from southern South America. The new specimen increases the taxonomic diversity of folivores from the Middle Miocene of the La Venta site, Colombia and provides further evidence that Megatherioidea were widely distributed throughout South America since the Middle Miocene.

Intestinal protozoan and metazoan parasites of public health concern have been found infecting non-human primates (NHPs). Since zoonotic parasite transmission can be linked to ecosystem transformation due to close contact between human and NHPs, this study aimed to morphologically identify intestinal parasites infecting NHPs living in seven forest fragments in Colombia and to molecularly characterise selected parasite taxa of zoonotic interest (Giardia sp. and Ascaris sp.). Building on and updating previous parasite surveys on free-ranging platyrrhines, 212 faecal samples were collected from wild Alouatta seniculus, Ateles hybridus, Aotus griseimembra, Cebus versicolor, Saimiri cassiquiarensis, and Sapajus apella. Flotation and faecal smears were performed in order to identify parasites based on morphological characteristics. Samples microscopically classified as positive for Giardia sp. and Ascaris sp. were then processed for molecular characterisation. Amplification of the triosephosphate isomerase (TPI) and the 18S genes was done for Giardia sp., while for Ascaris sp. a PCR-RPLF of the entire ITS region was carried out. About 96% of the samples were positive for intestinal parasites, including: protozoans (Blastocystis sp., Balantidium sp., Dientamoeba fragilis-like, Entamoeba sp., Giardia sp., Eimeria sp.), nematodes (Ascaris sp., strongyliform larvae, Trypanoxyuris sp., Ancylostomatidae), trematodes (Controrchis sp., Trematoda), cestodes (Hymenolepis sp., Cestoda), and acanthocephalans. By microscopy, the prevalence of Giardia sp. and Ascaris sp. was 16.5% and 0.9%, respectively. Later on, Giardia duodenalis (Assemblages A and B) and Ascaris lumbricoides were identified through molecular techniques. This study provides new information of intestinal parasites infecting free-ranging NHPs exposed to anthropogenic disturbance. The finding of parasites with zoonotic potential suggests epidemiological implications in NHP conservation and human health, at the human-NHP interface.

Small carnivore activity is usually constrained by multiple factors, including moonlight, rainfall seasonality, intraguild relationships, and availability of prey. This study aimed to analyze the effects of such factors on the activity of clouded tiger-cats (Leopardus pardinoides). Data (time-stamp detections) were collected via 58 camera traps in three protected cloud forests of the Middle Cauca, Colombia. Differences in activity among seasons and species were tested using Watson-two-tests. The temporal overlap between clouded tiger-cats and their intraguild predators/competitors and prey was estimated using kernel density functions. All species were seasonally invariant in their activities. Clouded tiger-cats were mainly nocturnal and lunarphobic. There was high temporal overlap (80 %) between the daily activity of clouded tiger-cats and small mammals, which increased during the nocturnal activity (92 %). Contrastingly, low temporal overlap was found between clouded tiger-cats and tayras (19 %), weasels (19 %), and dogs (20 %). Ocelots were cathemeral and showed a moderate temporal overlap (65 %) with the daily activity of clouded tiger-cats. However, temporal overlap between the nocturnal activity of both felids was found to be higher (81 %). Nocturnal behavior in clouded tiger-cats can favor prey encounters during darker nights while avoiding diurnal predators/competitors. The evidence of diurnal activity in domestic dogs could be indicative of a free-roaming population that rely on human subsides in the surroundings of protected areas, suggesting the need for management actions. Competitive pressures exerted by ocelots on clouded tiger-cats may be alleviated through the differential use of space, or by the apparent rarity of the former in highland cloud forests.

Direct evidence of predation and other trophic relationships provide valuable information about trophic interactions between species in palaeo-communities. Data on ecological interactions amongst extant apex predators open a unique opportunity to better understand how sympatric apex predators coexisted or interacted with each other in the past. Here, we describe direct evidence of a predation or scavenging event in which we hypothesize that a medium-sized caiman (possibly Purussaurus neivensis ) consumed (either through scavenging or through direct predation) a large terror bird. The distal part of a left tibiotarsus from a phorusrhacid had four pits inflicted on the cortical bone, and no signs of healing, suggesting it did not survive this trophic event. This record contributes to our current understanding of prey consumed by P. neivensis in the wetlands of the Pebas System of South America and indicates that large phorusrhacids might have had higher predation risk than previously expected. This study provides evidence of a trophic relation between apex predators and the complexity of trophic interactions in the diverse vertebrate palaeo-community of La Venta in the Middle Miocene of northern South America.

In mammals, competition for resources is known to be one of the most important determinants of grouping patterns. As a result, some animals have evolved fission-fusion strategies that allow them to balance the benefits and costs of living in large groups. In this study, we evaluated the influence of fruit availability on fruit consumption and grouping patterns in two species of spider monkeys living in ecosystems with different levels of habitat degradation: brown spider monkeys (Ateles hybridus) living in a fragmented tropical forest in the inter-Andean Rio Magdalena valley of Colombia, and white-bellied spider monkeys (Ateles belzebuth) living in a continuous tropical evergreen forest in Amazonian Ecuador. Through focal animal sampling, we recorded diet, subgroup size, and fission/fusion events involving the subgroup that contained the focal animal, and we estimated habitat-wide fruit availability every 2 weeks on phenological transects in the two habitats. We recorded behavioral and ecological data for brown spider monkeys from July 2009 to November 2012 obtaining 2270 hours of focal sampling, and for white-bellied spider monkeys from August 2006 to February 2017 obtaining 7000 hours of focal sampling. We used generalized linear mixed effects models to evaluate the relationship between fruit availability and both fruit consumption and subgroup size. In the relatively undisturbed Ecuadorian rainforest site, both fruit consumption and subgroup size of white-bellied spider monkeys were positively correlated with seasonal fruit availability. By contrast, in the fragmented Colombian tropical forest, we found no significant relationship between fruit availability and either fruit consumption or subgroup size for brown spider monkeys. Although differences between our two study groups may be due to species differences, the two species are very closely related, and spider monkeys in general show similar responses to degraded habitats. Thus, we argue that our results support the hypothesis that grouping patterns in fission-fusion species are influenced by food availability and suggests that habitat degradation might disrupt this relationship.

Taxonomic classifications of the gracile capuchin monkeys, Cebus, have traditionally been based on cranio-dental and pelage characters. Advances in molecular biology have provided information on the evolutionary history of the genus but the taxonomy and distribution limits of taxa in the northern Andes are still under debate. To assess morphometric disparities and compare the results with hypotheses based on genetic evidence for Cebus taxonomy, we used 2D geometric morphometrics on 206 adult specimens (127 males, 77 females, 2 unsexed) belonging to 12 taxa by assigning Type I landmarks in the frontal (11), lateral (18) and ventral (16) views of the skull, and 14 in the mandible. Our results show that skull shape is more variable than centroid size and that morphometric disparities exist across and within all three geographic groups (Central America, Andes, and Amazon). Although skull shape in Cebus tends to vary slightly, our results suggest differences among some taxa and highlight the utility of studying shape in addition to methods that have focused on size. Some results concur with the taxonomic classifications based on molecular evidence but it is important to note that Cebus species are wide-ranging with high inter- and intraspecific phenotypic variability in diverse ecological conditions. This makes it difficult to provide species diagnoses based just on morphometric or morphological characters and suggests the need to integrate different sources of evidence to resolve uncertainties about the taxonomy and the evolutionary relationships in the genus.

Presentamos registros recientes y novedosos (a través de fototampeo) del pecarí de labio blanco (Tayassu pecari) en una localidad del Magdalena Medio (DRMI Ciénaga de Barbacoas, Yondó, Colombia) donde la especie se reporta como extinta localmente. Los registros provienen de una única localidad a lo largo de tres muestreos, sin embargo, no se reportaron más sitios con presencia de la especie en nuestros trabajos a lo largo de diferentes localidades del Magdalena Medio o en otros estudios publicados. Esto sugiere que la especie tiene baja abundancia y ocupación en el paisaje altamente transformado de este valle interandino. Una búsqueda de registros adicionales en plataformas digitales arrojó colectas históricas en el Caribe Colombiano y un registro reciente en el valle del rio Cauca en Antioquia (Colombia), el cual debe ser confirmado en campo. La presencia de pecarí de labio blanco, junto con otras especies amenazadas como el Mono Araña Café, la Danta colombiana, el Jaguar y el Oso Hormiguero Gigante, resaltan la necesidad de restaurar el paisaje fragmentado del Magdalena Medio para mantener su diversidad a largo plazo.

BACKGROUND: The Middle Miocene fauna of La Venta, Colombia, offers a grand opportunity to understand low-latitude South American ecosystems prior to the late Cenozoic Great American Biotic Interchange (GABI). We present new material of two proterotheriid litopterns, Villarroelia totoyoi and Mesolicaphrium sanalfonense, and a macraucheniid litoptern, Theosodon, from La Venta. During the GABI, North and South American faunas intermixed, after which some lineages proliferated and others died out. We conducted an ecomorphological analysis of 11 North and South American faunas pre-dating and post-dating the GABI by scoring all mid- to large-sized mammalian herbivores on their body size, tooth morphology, and feeding height. RESULTS: The fossils studied here offer new information on the deciduous dentition of M. sanalfonense and mandible of the La Venta Theosodon. Pre-GABI South American faunas were more ecomorphologically diverse than their North American counterparts. The post-GABI Pleistocene fauna exhibited similar ecomorphological diversity to pre-GABI South American faunas, but modern faunas show this diversity was mostly lost in the end-Pleistocene extinctions. CONCLUSIONS: The new litoptern fossils provide previously unknown information on these species’ morphology, but they do not resolve outstanding systematic and phylogenetic questions. Discrepancies in ecomorphological diversity between pre-GABI North and South American faunas is attributable to the presence of small, high-feeding (arboreal) taxa and hypselodont (ever-growing cheek teeth) taxa in South America, which North America lacked. Arboreal herbivores (porcupines and primates) experienced some success in North America after dispersing during the GABI. Although hypselodont xenarthrans were successful in post-GABI North America, the fact that most other hypselodont lineages went extinct during and after the GABI suggests that dental morphology may not fully capture the ecomorphological diversity in diet of North American herbivores. Future studies could examine faunas immediately before and after the GABI to uncover the precise dynamics of the interchange and why certain lineages succeeded while others failed.

Phorusrhacids correspond to a group of birds considered to be apex predators, which are a common element of the American fossil Cenozoic avifauna, especially in Argentina, where it is not unusual to find at least two species of terror birds. Nevertheless, the presence of more than one species of terror bird outside Argentina is null. Here we report a second terror bird from the middle Miocene of La Venta locality. The new specimen could reach approximately 180 kg, being about 15% larger than the previous report of a terror bird for the locality. Although it is not possible to completely discard the possibility of these two specimens belonging to a dimorphic species, morphological differences may indicate so. Certainly, the presence of two gigantic terror birds coexisting in the La Venta locality represents an interesting scenario for further studies on their ecology and niche partitioning; this could be an argument for the presence of large open areas within the forests and wetlands of La Venta, further supporting the complex and diverse ecosystems in this region during the Middle Miocene period.

Tropical floodplain lakes are increasingly impacted by human activities, yet their pathways of spatial and temporal degradation, particularly under varying hydrological connectivity regimes and climate change, remain poorly understood. This study examines surface-sediment samples and 210Pb-dated sediment cores from six floodplain lakes, representing a gradient in hydrological connectivity in the lower Magdalena River Basin, Colombia. We analysed temporal and spatial variations in several sediment biogeochemical indicators: the concentration and flux of nutrients, heavy metals, and organic matter (OM), and redox conditions, flooding and erosion. Multiple factor analysis (MFA) of surface-sediments identified redox conditions, OM, flooding, heavy metals and lake connectivity as the main contributors to spatial variability within- and between-lakes sediments, accounting for 48 % of the total variation. Additionally, no clear distinction was found between littoral and open-water sediment characteristics. Isolated lakes sediments exhibited reductive conditions rich in OM and nutrients, whereas connected lakes sediments showed greater heavy metal enrichment and higher concentrations of coarse river-fed material. Generalised additive models identified significant changes in the biogeochemical indicators since the late 1800s, that accelerated post-1980s. Shifts in OM, erosion, flooding, redox conditions, land-cover change, heavy metals and climate were identified by MFA as the main drivers of change, explaining 60 %-71 % of the variation in the connected lakes and 53 %-72 % in the isolated lakes. Post-1980s, connected lakes transitioned from conditions of higher accumulation of OM and little erosion to higher accumulation of heavy metals and river-fed material. Conversely, isolated lakes, shifted from detrital-heavy metal-rich sediments to OM-, and nutrient-rich, reductive sediments. Sedimentation rates also surged post-1980s, particularly in highly connected lakes, from 0.14 ± 0.07 g cm² yr⁻¹ to 0.5 ± 0.5 g cm² yr⁻¹, with elevated fluxes of metals, OM and nutrients. These changes in sediment biogeochemistry align with deforestation, river regulation and prolonged dry periods, highlighting the complexities behind establishing reliable reference conditions for pollution assessments in large, human-impacted tropical river systems.