Rapid facial mimicry in Platyrrhini: Play face replication in spider monkeys (Ateles fusciceps, Ateles hybridus, and Ateles paniscus).

Rapid facial mimicry (RFM), the rapid and automatic replication of facial expression perceived, is considered a basic form of empathy and was investigated mainly during play. RFM occurs in Catarrhini (Old World primates), but it is not still demonstrated in Platyrrhini (New World primates). For this reason, we collected video data on playful interactions (Nplay_interactions = 149) in three species of spider monkeys (Ateles fusciceps-N = 11, Ateles hybridus-N = 14, and Ateles paniscus-N = 6) housed at La Vallée des Singes and the ZooParc de Beauval (France). For the first time, we demonstrated the occurrence of RFM in Platyrrhini (analyzing 175 events). Players' sex, age, species, relationship quality, and kinship did not modulate RFM probably due to the species' complex fission-fusion dynamics and flexible interindividual social relationships. Compared to the absence of any playful expressions or the presence of only not replicated play face, RFM prolonged the session duration and was sequentially associated with more types of more intense offensive playful patterns (patterns aimed at attacking/pursuing the playmate). We proposed that RFM may favor synchronization and context sharing between players, thus decreasing the risk of behavior misinterpretation while simultaneously fostering a more competitive nature of play. In conclusion, this study stimulates additional research on the evolutionary origins of motor mimicry in primates, possibly dating back to before the divergence of New and Old World monkeys. Furthermore, it also points toward the possibility that RFM may not always lead to cooperation but also to competition, depending on the context and species' social and cognitive features.

Chromatic discrimination in fixed saturation levels from tufted capuchin monkeys with different color vision genotypes.

Recent research has proposed new approaches to investigate color vision in Old World Monkeys by measuring suprathreshold chromatic discrimination. In this study, we aimed to extend this approach to New World Monkeys with different color vision genotypes by examining their performance in chromatic discrimination tasks along different fixed chromatic saturation axes. Four tufted capuchin monkeys were included in the study, and their color vision genotypes were one classical protanope, one classical deuteranope, one non-classical protanope, and a normal trichromat. During the experiments, the monkeys were required to perform a chromatic discrimination task using pseudoisochromatic stimuli with varying target saturations of 0.06, 0.04, 0.03, and 0.02 u'v' units. The number of errors made by the monkeys along different chromatic axes was recorded, and their performance was quantified using the binomial probability of their hits during the tests. Our results showed that dichromatic monkeys made more errors near the color confusion lines associated with their specific color vision genotypes, while the trichromatic monkey did not demonstrate any systematic errors. At high chromatic saturation, the trichromatic monkey had significant hits in the chromatic axes around the 180° chromatic axis, whereas the dichromatic monkeys had errors in colors around the color confusion lines. At lower saturation, the performance of the dichromatic monkeys became more challenging to differentiate among the three types, but it was still distinct from that of the trichromatic monkey. In conclusion, our findings suggest that high saturation conditions can be used to identify the color vision dichromatic phenotype of capuchin monkeys, while low chromatic saturation conditions enable the distinction between trichromats and dichromats. These results extend the understanding of color vision in New World Monkeys and highlight the usefulness of suprathreshold chromatic discrimination measures in exploring color vision in non-human primates.

Reversible deactivation of motor cortex reveals that areas in parietal cortex are differentially dependent on motor cortex for the generation of movement.

Primates are characterized by specializations for manual manipulation, including expansion of posterior parietal cortex (PPC) and, in Catarrhines, evolution of a dexterous hand and opposable thumb. Previous studies examined functional interactions between motor cortex and PPC in New World monkeys and galagos, by inactivating M1 and evoking movements from PPC. These studies found that portions of PPC depend on M1 to generate movements. We now add a species that more closely resembles humans in hand morphology and PPC: macaques. Inactivating portions of M1 resulted in all evoked movements being reduced (28%) or completely abolished (72%) at the PPC sites tested (in areas 5L, PF, and PFG). Anterior parietal area 2 was similarly affected (26% reduced and 74% abolished) and area 1 was the least affected (12% no effect, 54% reduced, and 34% abolished). Unlike previous studies in New World monkeys and galagos, interactions between both nonanalogous (heterotopic) and analogous (homotopic) M1 and parietal movement domains were commonly found in most areas. These experiments demonstrate that there may be two parallel networks involved in motor control: a posterior parietal network dependent on M1 and a network that includes area 1 that is relatively independent of M1. Furthermore, it appears that the relative size and number of cortical fields in parietal cortex in different species correlates with homotopic and heterotopic effect prevalence. These functional differences in macaques could contribute to more numerous and varied muscle synergies across major muscle groups, supporting the expansion of the primate manual behavioral repertoire observed in Old World monkeys.NEW & NOTEWORTHY Motor cortex and anterior and posterior parietal cortex form a sensorimotor integration network. We tested the extent to which parietal areas could initiate movements independent of M1. Our findings support the contention that, although areas 2, 5L, PF, and PFG are highly dependent on M1 to produce movement, area 1 may constitute a parallel corticospinal pathway that can function somewhat independently of M1. A similar functional architecture may underlie dexterous tool use in humans.

Growth and microanatomy of the paranasal sinuses in two species of New World monkeys.

Paranasal sinuses of living apes and humans grow with positive allometry, suggesting a novel mechanism for bone enlargement. Here, we examine the paranasal sinuses of the owl monkey (Aotus spp.) and a tamarin (Saguinus midas) across postnatal development. The prediction that paranasal sinuses grow disproportionately faster than the main nasal chamber is tested. We used diffusible iodine-based contrast-enhanced computed tomography and histology to study sinuses in eight Aotus and three tamarins ranging from newborn to adult ages. Sinuses were segmented at the mucosa-air cavity interface and measured in volume. All sinuses were lined by a ciliated respiratory epithelium, except for the ethmoid air cells in Aotus, which are lined in part by olfactory epithelium. An age comparison indicates that only the maxillary sinus and ethmoid air cells are present in newborns, and two additional sinuses (invading the orbitosphenoid and the frontal bone), do not appear until late infancy or later. Comparing newborns and adults, the main nasal airway is 10 times larger in the adult Aotus and ~ 6.5 times larger in adult Saguinus. In contrast, the maxillary sinus far exceeds this magnitude of difference: 24 times larger in the adult Aotus and 46 times larger in adult Saguinus. The frontal sinuses add significantly to total paranasal space volume in both species, but this growth is likely delayed until juvenile age. Results suggest ethmoid air cells expand the least. These results support our prediction that most paranasal sinuses have a distinctly higher growth rate compared to the main nasal chamber.

Isolation and Genetic Characterization of Toxoplasma gondii from a Patas Monkey (Erythrocebus patas) in China.

Many cases of Toxoplasma gondii infection have been reported worldwide in non-human primates (NHPs), especially in captive New World monkeys. However, few studies on toxoplasmosis in Old World monkeys have been conducted. In this study, serological and molecular biological analyses were carried out to look for T. gondii antibodies and T. gondii infection in 13 NHPs from China. T. gondii infection was confirmed in 8 NHP cases. T. gondii antibodies were detected in 1/5 New World monkeys and in 4/7 Old World monkeys. T. gondii DNA was detected in 3/5 New World monkeys and 5/7 Old World monkeys. The one ring-tailed lemur was negative for both antibodies and DNA of T. gondii. The most common clinical manifestations of T. gondii infection were malaise, poor appetite, emaciation, and foamy nasal discharge. The most common histopathological findings were interstitial pneumonia, necrotic hepatitis, necrotizing myocarditis, lymphadenitis, and necrotic splenitis. One viable T. gondii strain was successfully isolated from the myocardium of a patas monkey (Erythrocebus patas) by bioassay in mice. T. gondii tachyzoites were obtained from cell cultures and were designated as TgMonkeyCHn2. The genotype of this strain belongs to ToxoDB genotype #9, and the allele of ROP18/ROP5 gene was 3/6. TgMonkeyCHn2 tachyzoites were avirulent in Swiss mice. To our knowledge, this is the first report of fatal toxoplasmosis in a patas monkey. T. gondii infection in patas monkeys may indicate environmental contamination by oocysts. The patas monkey is a new host record for T. gondii.

An eosimiid primate of South Asian affinities in the Paleogene of Western Amazonia and the origin of New World monkeys.

Recent fossil discoveries in Western Amazonia revealed that two distinct anthropoid primate clades of African origin colonized South America near the Eocene/Oligocene transition (ca. 34 Ma). Here, we describe a diminutive fossil primate from Brazilian Amazonia and suggest that, surprisingly, a third clade of anthropoids was involved in the Paleogene colonization of South America by primates. This new taxon, Ashaninkacebus simpsoni gen. et sp. nov., has strong dental affinities with Asian African stem anthropoids: the Eosimiiformes. Morphology-based phylogenetic analyses of early Old World anthropoids and extinct and extant New World monkeys (platyrrhines) support relationships of both Ashaninkacebus and Amamria (late middle Eocene, North Africa) to the South Asian Eosimiidae. Afro-Arabia, then a mega island, played the role of a biogeographic stopover between South Asia and South America for anthropoid primates and hystricognathous rodents. The earliest primates from South America bear little adaptive resemblance to later Oligocene-early Miocene platyrrhine monkeys, and the scarcity of available paleontological data precludes elucidating firmly their affinities with or within Platyrrhini. Nonetheless, these data shed light on some of their life history traits, revealing a particularly small body size and a diet consisting primarily of insects and possibly fruit, which would have increased their chances of survival on a natural floating island during this extraordinary over-water trip to South America from Africa. Divergence-time estimates between Old and New World taxa indicate that the transatlantic dispersal(s) could source in the intense flooding events associated with the late middle Eocene climatic optimum (ca. 40.5 Ma) in Western Africa.

Molecular Evidence Supports Five Lineages within Chiropotes (Pitheciidae, Platyrrhini).

Pitheciines have unique dental specializations among New World monkeys that allow them to feed on fruits with hard pericarps, thus playing a major role as seed predators. The three extant pitheciine genera, Pithecia, Cacajao and Chiropotes, are all endemic to the Amazon region. Because of the uncertainties about interspecific relationships, we reviewed the systematics and taxonomy of the genus Chiropotes. The phylogenetic analyses were performed based on Maximum Likelihood and Bayesian Inference, while species delimitation analyses were carried out using multispecies coalescent methods. In addition, we estimated genetic distances, divergence time and the probable ancestral distribution of this genus. Our results support five species of Chiropotes that emerged during the Plio-Pleistocene. Biogeographic estimates suggest that the ancestor of the current Chiropotes species occupied the endemism areas from Rondônia and Tapajós. Later, subsequent radiation and founder effects associated with the formation of the Amazonian basins probably determined the speciation events within Chiropotes.

Manual action expectation and biomechanical ability in three species of New World monkey.

Being able to anticipate another's actions is a crucial ability for social animals because it allows for coordinated reactions. However, little is known regarding how hand morphology and biomechanical ability influences such predictions. Sleight of hand magic capitalizes on the observer's expectations of specific manual movements,1,2 making it an optimal model to investigate the intersection between the ability to manually produce an action and the ability to predict the actions of others. The French drop effect involves mimicking a hand-to-hand object transfer by pantomiming a partially occluded precision grip. Therefore, to be misled by it, the observer ought to infer the opposing movement of the magician's thumb.3 Here, we report how three species of platyrrhine with inherently distinct biomechanical ability4,5,6-common marmosets (Callithrix jacchus), Humboldt's squirrel monkeys (Saimiri cassiquiarensis), and yellow-breasted capuchins (Sapajus xanthosternos)-experienced this effect. Additionally, we included an adapted version of the trick using a grip that all primates can perform (power grip), thus removing the opposing thumb as the causal agent of the effect. When observing the French drop, only the species with full or partial opposable thumbs were misled by it, just like humans. Conversely, the adapted version of the trick misled all three monkey species, regardless of their manual anatomy. The results provide evidence of a strong interaction between the physical ability to approximate a manual movement and the predictions primates make when observing the actions of others, highlighting the importance of physical factors in shaping the perception of actions.

Comparative gastrointestinal organ lengths among Amazonian primates (Primates: Platyrrhini).

OBJECTIVES: The morphological features of the gastrointestinal tract (GIT) in mammals reflect a species' food niche breadth and dietary adaptations. For many wild mammals, the relationship between the structure of the GIT and diet is still poorly understood, for example, the GIT for frugivorous primates is usually classified as unspecialized and homogeneous. Here, we compare the GIT structure of 13 primate species from the three families of extant platyrrhines (Atelidae, Pitheciidae, and Cebidae) in Amazonia, and discuss possible evolutionary adaptations to different diets and trophic niches. METHODS: We measured the length of the esophagus, stomach, small intestine, large intestine, cecum, colon, and rectum of the digestive tracts of 289 primate specimens. We determined the allometric relationships of the different tubular organs with the total length of the GIT as a proxy of specimen body size. Allometric parameters were used to establish the quotients of differentiation of every organ for each primate specimen. RESULTS: There was a high differentiation in structure of the digestive organs among genera. Alouatta specimens clearly separated from the other genera based on dissimilarities in gastric, colonic, and rectal quotients, likely linked to the fermentation of plant contents. In contrast, all cebines (Sapajus, Cebus, and Saimiri) and Cacajao species had similar small intestine quotients, which is expected due to their high rates of animal matter consumed. CONCLUSIONS: We show that diverse adaptations in digestive structure exist among frugivorous primates, which in turn reflect different dietary patterns within this group that may enable the geographic coexistence of different primate species.

Potentially reduced fusogenicity of syncytin-2 in New World monkeys.

Syncytin-2 is a membrane fusion protein involved in placenta development that is derived from the endogenous retrovirus envelope gene acquired in the common ancestral lineage of New World and Old World monkeys (OWMs). It is known that syncytin-2 is conserved between apes and OWMs, suggesting its functional importance; however, syncytin-2 of common marmosets (Callithrix jacchus) exhibits lower fusogenic activity than those of humans and OWMs in human cell lines. To obtain insight into the functional diversity of syncytin-2 genes in primates, we examined the syncytin-2 gene in New World monkeys (NWMs). We experimentally evaluated the cell fusion ability of syncytin-2 in humans, C. jacchus, and tufted capuchins (Sapajus apella). We found that the cell fusion ability of S. apella was lower than that of human syncytin-2. Chimeric syncytin-2 constructs revealed that the amino acid differences in the surface unit of S. apella syncytin-2 were responsible for the weak cell fusion activity. In addition, genomic sequence analyses of syncytin-2 revealed that the open reading frames (ORFs) of syncytin-2 were highly conserved in seven apes and 22 OWMs; however, the syncytin-2 ORFs of three of 12 NWM species were truncated. Our results suggest that syncytin-2 in several NWMs may be of less importance than in OWMs and apes, and other syncytin-like genes may be required for placental development in various NWM species.

Total evidence phylogeny of platyrrhine primates and a comparison of undated and tip-dating approaches.

There have been multiple published phylogenetic analyses of platyrrhine primates (New World monkeys) using both morphological and molecular data, but relatively few that have integrated both types of data into a total evidence approach. Here, we present phylogenetic analyses of recent and fossil platyrrhines, based on a total evidence data set of 418 morphological characters and 10.2 kilobases of DNA sequence data from 17 nuclear genes taken from previous studies, using undated and tip-dating approaches in a Bayesian framework. We compare the results of these analyses with molecular scaffold analyses using maximum parsimony and Bayesian approaches, and we use a formal information theoretic approach to identify unstable taxa. After a posteriori pruning of unstable taxa, the undated and tip-dating topologies appear congruent with recent molecular analyses and support largely similar relationships, with strong support for Stirtonia as a stem alouattine, Neosaimiri as a stem saimirine, Cebupithecia as a stem pitheciine, and Lagonimico as a stem callitrichid. Both analyses find three Greater Antillean subfossil platyrrhines (Xenothrix, Antillothrix, and Paralouatta) to form a clade that is related to Callicebus, congruent with a single dispersal event by the ancestor of this clade to the Greater Antilles. They also suggest that the fossil Proteropithecia may not be closely related to pitheciines, and that all known platyrrhines older than the Middle Miocene are stem taxa. Notably, the undated analysis found the Early Miocene Panamacebus (currently recognized as the oldest known cebid) to be unstable, and the tip-dating analysis placed it outside crown Platyrrhini. Our tip-dating analysis supports a late Oligocene or earliest Miocene (20.8-27.0 Ma) age for crown Platyrrhini, congruent with recent molecular clock analyses.

Evidence linking APOBEC3B genesis and evolution of innate immune antagonism by gamma-herpesvirus ribonucleotide reductases.

Viruses have evolved diverse mechanisms to antagonize host immunity such as direct inhibition and relocalization of cellular APOBEC3B (A3B) by the ribonucleotide reductase (RNR) of Epstein-Barr virus. Here, we investigate the mechanistic conservation and evolutionary origin of this innate immune counteraction strategy. First, we find that human gamma-herpesvirus RNRs engage A3B via largely distinct surfaces. Second, we show that RNR-mediated enzymatic inhibition and relocalization of A3B depend upon binding to different regions of the catalytic domain. Third, we show that the capability of viral RNRs to antagonize A3B is conserved among gamma-herpesviruses that infect humans and Old World monkeys that encode this enzyme but absent in homologous viruses that infect New World monkeys that naturally lack the A3B gene. Finally, we reconstruct the ancestral primate A3B protein and demonstrate that it is active and similarly engaged by the RNRs from viruses that infect humans and Old World monkeys but not by the RNRs from viruses that infect New World monkeys. These results combine to indicate that the birth of A3B at a critical branchpoint in primate evolution may have been a driving force in selecting for an ancestral gamma-herpesvirus with an expanded RNR functionality through counteraction of this antiviral enzyme.

Size reduction and skull shape parallelism following the evolutionary forest-to-savanna transition in Platyrrhini monkeys.

There are strong physiological and behavioral differences that allow animals to live in forests versus savannas. For example, terrestrial forest-dwelling mammals tend to be small compared to species living in savannas. Robust capuchin monkeys (genus Sapajus) are widespread in tropical South America, occurring in both forest and savanna environments, with forest species considered basal in an evolutionary context. Whether or not skull shape and size variations are associated with variation in resource use remains unknown, particularly for the two species living in savanna (Sapajus libidinosus and S. cay). Here we show that savanna species present convergent size and skull characteristics that may facilitate living in this new environment. Geometric morphometric methods were used to assess skull size and shape variation for 184 Sapajus specimens distributed across South America. We used phylogenetic generalized least squares to test size against environmental variables and multivariate morphological trajectories/partial least square analyses on the skull shape to detect shape differences in specimens between forest and savanna biomes. Our findings reveal Sapajus size reduction in the evolutionary transition from forest to savanna, a process related to increasing seasonality. Moreover, we found morphological parallelism in the skull (e.g., muzzle shortening) and (large) molars in the two savanna species, features that may facilitate the processing of harder food such as fallback resources. We associate these phenotypic differences to the evolutionary process of colonizing the savannas by primates (including early hominins), leading to morphological adaptations to tolerate stressful, seasonal environments, such as body size reduction and ingestion and mastication of tough foods.

Immunoglobulin heavy constant gamma gene evolution is modulated by both the divergent and birth-and-death evolutionary models.

Immunoglobulin G (IgG) is one of the five antibody classes produced in mammals as part of the humoral responses accountable for protecting the organisms from infection. Its antibody heavy chain constant region is encoded by the Ig heavy-chain gamma gene (IGHG). In humans, there are four IGHG genes which encode the four subclasses, each with a specialized effector function. Although four subclasses of IgG proteins have also been reported in macaques, this does not appear to be the rule for all primates. In Platyrrhini, IgG has been stated to be encoded by a single-copy gene. To date, it remains unknown how the IGHG has expanded or contracted in the primate order; consequently, we have analyzed data from 38 primate genome sequences to identify IGHG genes and describe the evolution of IGHG genes in primate order. IGHG belongs to a multigene family that evolves by the birth-death evolutionary model in primates. Whereas Strepsirrhini and Platyrrhini have a single-copy gene, in Catarrhini, it has expanded to several paralogs in their genomes; some deleted and others pseudogenized. Furthermore, episodic positive selection may have promoted a species-specific IgG effector function. We propose that IgG evolved to reach an optimal number of copies per genome to adapt their humoral immune responses to different environmental conditions. This study has implications for biomedical trials using non-human primates.

Origin and Deep Evolution of Human Endogenous Retroviruses in Pan-Primates.

Human endogenous retroviruses (HERVs) are viral "fossils" in the human genome that originated from the ancient integration of exogenous retroviruses. Although HERVs have sporadically been reported in nonhuman primate genomes, their deep origination in pan-primates remains to be explored. Hence, based on the in silico genomic mining of full-length HERVs in 49 primates, we performed the largest systematic survey to date of the distribution, phylogeny, and functional predictions of HERVs. Most importantly, we obtained conclusive evidence of nonhuman origin for most contemporary HERVs. We found that various supergroups, including HERVW9, HUERSP, HSERVIII, HERVIPADP, HERVK, and HERVHF, were widely distributed in Strepsirrhini, Platyrrhini (New World monkeys) and Catarrhini (Old World monkeys and apes). We found that numerous HERVHFs are spread by vertical transmission within Catarrhini and one HERVHF was traced in 17 species, indicating its ancient nature. We also discovered that 164 HERVs were likely involved in genomic rearrangement and 107 HERVs were potentially coopted in the form of noncoding RNAs (ncRNAs) in humans. In summary, we provided comprehensive data on the deep origination of modern HERVs in pan-primates.

Sex chromosome systems in Neotropical Primates: What have we learnt so far from cytogenetics and genomics?

Neotropical Primates (Platyrrhini) show great diversity in their life histories, ecology, behaviour and genetics. This diversity extends to their chromosome complements, both to autosomes and to sex chromosomes. In this contribution, we will review what is currently known about sex chromosomes in this group, both from cytogenetic and from genomic evidence. The X and Y chromosomes in Neotropical Primates, also known as New World Monkeys, have striking structural differences compared with Old World Monkeys when Catarrhini sex chromosomes are considered. The XY bivalent displays a different meiotic behaviour in prophase I, and their Y chromosome shows extensive genomic differences. Even though the most widespread sex chromosome system is the XX/XY and thus considered the ancestral one for Platyrrhini, modifications of this sexual system are observed within this group. Multiple sex chromosome systems originated from Y-autosome translocations were described in several genera (Aotus, Callimico and Alouatta). In the howler monkeys, genus Alouatta, an independent origin of the sexual systems in South American and Mesoamerican species was postulated. All the above-mentioned evidence suggests that the Y chromosome of Platyrrhini has a different evolutionary history compared with the Catarrhini Y. There is still much to understand regarding their sex chromosome systems.

IgG subclasses in New World Monkeys: an issue for debate?

Immunoglobulin G (IgG) is an essential antibody in adaptive immunity; a differential expansion of the gene encoding the Fc region (IGHG) of this antibody has been observed in mammals. Like humans, animal biomedical models, such as mice and macaques, have four functional genes encoding 4 IgG subclasses; however, the data for New World monkeys (NWM) seems contentious. Some publications argue for the existence of a single-copy gene for IgG Fc; however, a recent paper has suggested the presence of IgG subclasses in some NWM species. Here, we evaluated the genetic distances and phylogenetic relationships in NWM to assess the presence of IgG subclasses using the sequences of IGHG genes from 13 NWM species recovered from genomic data and lab PCR and cloning-based procedures available in GenBank. The results show that several sequences do not cluster into the expected taxon, probably due to cross-contamination during laboratory procedures, and consequently, they appear to be wrongly assigned. Additionally, several sequences reported as subclasses were shown to be 100% identical in the CH domains. The data presented here suggests that there is not enough evidence to establish the presence of IgG subclasses in NWM.

Unique nasal turbinal morphology reveals Homunculus patagonicus functionally converged on modern platyrrhine olfactory sensitivity.

The phyletic position of early Miocene platyrrhine Homunculus patagonicus is currently a matter of debate. Some regard it to be an early member of the Pitheciidae, represented today by the sakis, uakaris, and titi monkeys. Others view Homunculus as a stem platyrrhine, part of a group that diversified in Patagonia and converged in some respects on modern pitheciine dental and gnathic morphology and perhaps seed-eating specialization. New details of its internal nasal anatomy are pertinent to resolving this debate. In addition, they provide a new perspective on how modern platyrrhine olfactory sensitivity evolved. Here we reconstruct the internal nasal anatomy of Homunculus from high-resolution computed tomography scans. This species has three ethmoturbinals, the scrolls of bone in the nasal fossa that were covered in sensory epithelium in vivo. This condition stands in stark contrast to extant platyrrhines, and indeed to all other haplorhines, which have only two ethmoturbinals or, in the case of all pitheciid platyrrhines, only one ethmoturbinal. Quantitatively, however, Homunculus has an olfactory turbinal surface area that falls within the modern platyrrhine distribution, suggesting that while turbinal numbers differ, olfactory sensitivity in this taxon was likely comparable to that of modern platyrrhines. These new data from the fossil record provide further support for the hypothesis that Homunculus is a stem platyrrhine that functionally converged on modern platyrrhines rather than being an early representative of any extant clade.

Identification and evolutionary analysis of papillomavirus sequences in New World monkeys (genera Sapajus and Alouatta) from Argentina.

OBJECTIVE: In this study, we investigated the occurrence of papillomavirus (PV) infection in non-human primates (NHPs) in northeastern Argentina. We also explored their evolutionary history and evaluated the co-speciation hypothesis in the context of primate evolution. METHODS: We obtained DNA samples from 57 individuals belonging to wild and captive populations of Alouatta caraya, Sapajus nigritus, and Sapajus cay. We assessed PV infection by PCR amplification with the CUT primer system and sequencing of 337 bp (112 amino acids) of the L1 gene. The viral sequences were analyzed by phylogenetic and Bayesian coalescence methods to estimate the time to the most common recent ancestor (tMRCA) using BEAST, v1.4.8 software. We evaluated viral/host tree congruence with TreeMap v3.0. RESULTS: We identified two novel putative PV sequences of the genus Gammapapillomavirus in Sapajus spp. and Alouatta caraya (SPV1 and AcPV1, respectively). The tMRCA of SPV1 was estimated to be 11,941,682 years before present (ybp), and that of AcPV1 was 46,638,071 ybp, both before the coalescence times of their hosts (6.4 million years ago [MYA] and 6.8 MYA, respectively). Based on the comparison of primate and viral phylogenies, we found that the PV tree was no more congruent with the host tree than a random tree would be (P > 0.05), thus allowing us to reject the model of virus-host coevolution. CONCLUSION: This study presents the first evidence of PV infection in platyrrhine species from Argentina, expands the range of described hosts for these viruses, and suggests new scenarios for their origin and dispersal.

Endocranial asymmetry in New World monkeys: a comparative phylogenetic analysis of morphometric data.

Brain lateralization is a widespread phenomenon although its expression across primates is still controversial due to the reduced number of species analyzed and the disparity of methods used. To gain insight into the diversification of neuroanatomical asymmetries in non-human primates we analyze the endocasts, as a proxy of external brain morphology, of a large sample of New World monkeys and test the effect of brain size, home range and group sizes in the pattern and magnitude of shape asymmetry. Digital endocasts from 26 species were obtained from MicroCT scans and a set of 3D coordinates was digitized on endocast surfaces. Results indicate that Ateles, Brachyteles, Callicebus and Cacajao tend to have a rightward frontal and a leftward occipital lobe asymmetry, whereas Aotus, Callitrichinae and Cebinae have either the opposite pattern or no directional asymmetry. Such differences in the pattern of asymmetry were associated with group and home range sizes. Conversely, its magnitude was significantly associated with brain size, with larger-brained species showing higher inter-hemispheric differences. These findings support the hypothesis that reduction in inter-hemispheric connectivity in larger brains favors the lateralization and increases the structural asymmetries, whereas the patterns of shape asymmetry might be driven by socio-ecological differences among species.