Fossil Anthropoids Research Articles

A proximal radius of Barberapithecus huerzeleri from Castell de Barberà: Implications for locomotor diversity among pliopithecoids

Pliopithecoids are a diverse group of Miocene catarrhine primates from Eurasia. Their positional behavior is still unknown, and many species are known exclusively from dentognathic remains. Here, we describe a proximal radius (IPS66267) from the late Miocene of Castell de Barberà (Vallès-Penedès Basin, NE Iberian Peninsula) that represents the first postcranial specimen of the pliopithecoid Barberapithecus huerzeleri. A body mass estimate based on the radius is compared with dental estimates, and its morphology is compared with that of extant and fossil anthropoids by qualitative means as well as by landmark-based three-dimensional geometric morphometrics. The estimated body mass of ∼5 kg for IPS66267 closely matches the dental estimates for the (female) holotype, thereby discounting an alternative attribution to the large-bodied hominoid recorded at Castell de Barberà. In multiple features (oval and moderately tilted head with a pronounced lateral lip and a restricted articular area for the capitulum; proximodistally expanded proximal radioulnar joint; and short, robust, and anteroposteriorly compressed neck), the specimen differs from hominoids and resembles instead extant nonateline monkeys and stem catarrhines. The results of the morphometric analysis further indicate that the Barberapithecus proximal radius shows closer similarities with nonsuspensory arboreal cercopithecoids and the dendropithecid Simiolus. From a locomotor viewpoint, the radius of Barberapithecus lacks most of the features functionally related to climbing and/or suspensory behaviors and displays instead a proximal radioulnar joint that would have been particularly stable under pronation. On the other hand, the Barberapithecus radius differs from other stem catarrhines in the less anteroposteriorly compressed and less tilted radial head with a deeper capitular fovea, suggesting a somewhat enhanced mobility at the elbow joint. We conclude that pronograde arboreal quadrupedalism was the main component of the locomotor repertoire of Barberapithecus but that, similar to other crouzeliids, it might have displayed better climbing abilities than pliopithecids.

Variation of bony labyrinthine morphology in Mio-Plio-Pleistocene and modern anthropoids.

The bony labyrinth of the inner ear has special relevance when tracking phenotypic evolution because it is often well preserved in fossil and modern primates. Here we track the evolution of the bony labyrinth of anthropoid primates during the Mio-Plio-Pleistocene-the time period that gave rise to the extant great apes and humans. We use geometric morphometrics to analyze labyrinthine morphology in a wide range of extant and fossil anthropoids, including New World and Old World monkeys, apes, and humans; fossil taxa are represented by Aegyptopithecus, Microcolobus, Epipliopithecus, Nacholapithecus, Oreopithecus, Ardipithecus, Australopithecus, and Homo. Our results show that the morphology of the anthropoid bony labyrinth conveys a statistically significant phylogenetic signal especially at the family level. The bony labyrinthine morphology of anthropoids is also in part associated with size, but does not cluster by locomotor adaptations. The Miocene apes examined here, regardless of inferred locomotor behaviors, show labyrinthine morphologies distinct from modern great apes. Our results suggest that labyrinthine variation contains mixed signals and alternative explanations need to be explored, such as random genetic drift and neutral phenotypic evolution, as well as developmental constraints. The observed pattern in fossil and extant hominoids also suggests that an additional factor, for example, prenatal brain development, could have potentially had a larger role in the evolutionary modification of the bony labyrinth than hitherto recognized.

Is the middle cranial fossa a reliable predictor of temporal lobe volume in extant and fossil anthropoids?

We investigate the suitability of middle cranial fossa (MCF) size as a proxy for temporal lobe volume (TLV), examining the strength of the association between TLV and MCF metrics and assess the reliability predicting TLV in fossil anthropoids. The temporal lobe of the primate brain is a multimodal association cortex involved in long-term memory, auditory, and visual processing with unique specializations in modern humans for language comprehension. The MCF is the bony counterpart for the temporal lobe providing inferences for fossil hominin temporal lobe evolution. We now investigate whether the MCF is a suitable proxy for the temporal lobe. A sample of 23 anthropoid species (n = 232, including 13 fossil species) from computed tomography (CT) scans of ex vivo crania and magnetic resonance imaging (MRI) of the in vivo brain were generated into three-dimensional (3D) virtual models. Seven linear metrics were digitally measured on the right MCF with right TLV calculated from in vivo MRI. Regression analyses produced statistically significant correlations between TLV and all MCF metrics (r ≥ 0.85; p ≤ 0.0009) with TLV predictions within ±1 standard error and three MCF metrics (posterior-width, mid-length, and mid-width) the most reliable predictors of TLV with only one metric weakly associated with TLV. These findings indicate a strong association between the MCF and TLV, provide reliable predictors of fossil TLV that were previously unattainable, allow the inclusion of fragmentary fossil material, and enable inferences into the emergence of modern human temporal lobe morphology.

Human Carpal Evolution and its Implications for Hominin Locomotor Ancestry

The ancestral locomotor repertoire from which hominin bipedalism emerged remains a subject of frequent debate, with multiple competing hypotheses maintaining support among active researchers. This study contributes to this ongoing debate by reconstructing the morphological and locomotor evolution of hominoids based on patterns of morphometric variation in the capitate, hamate, lunate, and triquetrum among extant and fossil anthropoids, including humans and fossil hominins. Aspects of carpal morphology found to consistently covary with locomotor behavior are used to reconstruct adaptive transitions within the anthropoid clade associated with locomotor behavior. The prevalence of different locomotor behaviors at the origin of nested clades within Hominoidea, including the one we share with Pan, are also estimated.While there is some inconsistency of morphological covariation with function and phylogeny among carpal elements, results are consistent in supporting frequent parallelism during hominoid locomotor evolution. This support is strongest as it applies to suspensory behaviors, with the last common ancestors of both apes and great apes predicted to have remained quite generalized relative to the clades’ extant representatives. The last common ancestor of humans and chimpanzees/bonobos is also estimated to have lacked adaptations in association with knuckle‐walking, providing further support for the hominin clade having descended from a relatively generalized ancestral morphotype that is not well modeled by any of the surviving hominoid lineages.

Mandibular symphyseal fusion in fossil primates: Insights from correlated patterns of jaw shape and masticatory function in living primates

Variation in primate masticatory form and function has been extensively researched through both morphological and experimental studies. As a result, symphyseal fusion in different primate clades has been linked to either the recruitment of vertically directed balancing-side muscle force, the timing and recruitment of transversely directed forces, or both. This study investigates the relationship between jaw muscle activity patterns and morphology in extant primates to make inferences about masticatory function in extinct primates, with implications for understanding the evolution of symphyseal fusion. Three-dimensional mandibular landmark data were collected for 31 extant primates and nine fossil anthropoids and subfossil lemur species. Published electromyography (EMG) data were available for nine of the extant primate species. Partial least squares analysis and phylogenetic partial least squares analysis were used to identify relationships between EMG and jaw shape data and evaluate variation in jaw morphology. Primates with partial and complete symphyseal fusion exhibit shape-function patterns associated with the wishboning motor pattern and loading regime, in contrast to shape-function patterns of primates with unfused jaws. All fossil primates examined (except Apidium) exhibit jaw morphologies suggestive of the wishboning motor pattern demonstrated in living anthropoids and indriids. Partial fusion in Catopithecus, similar to indriids and some subfossil lemurs, may be sufficient to resist, or transfer, some amounts of transversely directed balancing-side muscle force at the symphysis, representing a transition to greater reliance on transverse jaw movement during mastication. Furthermore, possible functional convergences in physiological patterns during chewing (i.e., Archaeolemur) are identified.

A late Miocene hominid partial pelvis from Hungary

Substantial differences among the pelves of anthropoids have been central to interpretations of the selection pressures that shaped extant hominoids, yet the evolution of the hominoid pelvis has been poorly understood due to the scarcity of fossil material. A recently discovered partial hipbone attributed to the 10 million-year-old fossil ape Rudapithecus hungaricus from Rudabánya, Hungary, differs from the hipbones of cercopithecids and earlier apes in functionally significant ways. Comparisons were made to extant and other fossil anthropoids using combination of non-landmark-based and linear metrics. Measurements were taken on 3D polygonal models of hipbones collected using laser scans. These metrics capture functionally relevant morphology given the incomplete preservation of the Rudapithecus specimen. This fossil displays features that reflect changes in spinal musculature and torso structure found only in extant great and lesser apes among hominoids. Rudapithecus has an expanded cranial acetabular lunate surface related to orthograde positional behaviors, a shallow acetabulum and relatively short ischium like orangutans and hylobatids. It displays evidence of moderately coronally-oriented iliac blades as in all extant apes and Ateles, and flaring iliac blade shape of siamangs and great apes, associated with some level of spinal stiffness. However, this fossil lacks the long lower ilium that characterizes chimpanzees, gorillas and orangutans, associated with their reduction of the number of lumbar vertebrae. The R. hungaricus pelvis demonstrates that the extreme elongation of the lower ilium seen in extant great apes does not necessarily accompany adaptation to orthograde posture and forelimb-dominated arboreal locomotion in hominoid evolution. Lower iliac elongation appears to have occurred independently in each lineage of extant great apes, supporting the hypothesis that the last common ancestor of Pan and Homo may have been unlike extant great apes in pelvic length and lower back morphology.

Articular scaling and body mass estimation in platyrrhines and catarrhines: Modern variation and application to fossil anthropoids

Body mass is an important component of any paleobiological reconstruction. Reliable skeletal dimensions for making estimates are desirable but extant primate reference samples with known body masses are rare. We estimated body mass in a sample of extinct platyrrhines and Fayum anthropoids based on four measurements of the articular surfaces of the humerus and femur. Estimates were based on a large extant reference sample of wild-collected individuals with associated body masses, including previously published and new data from extant platyrrhines, cercopithecoids, and hominoids. In general, scaling of joint dimensions is positively allometric relative to expectations of geometric isometry, but negatively allometric relative to expectations of maintaining equivalent joint surface areas. Body mass prediction equations based on articular breadths are reasonably precise, with %SEEs of 17–25%. The breadth of the distal femoral articulation yields the most reliable estimates of body mass because it scales similarly in all major anthropoid taxa. Other joints scale differently in different taxa; therefore, locomotor style and phylogenetic affinity must be considered when calculating body mass estimates from the proximal femur, proximal humerus, and distal humerus. The body mass prediction equations were applied to 36 Old World and New World fossil anthropoid specimens representing 11 taxa, plus two Haitian specimens of uncertain taxonomic affinity. Among the extinct platyrrhines studied, only Cebupithecia is similar to large, extant platyrrhines in having large humeral (especially distal) joints. Our body mass estimates differ from each other and from published estimates based on teeth in ways that reflect known differences in relative sizes of the joints and teeth. We prefer body mass estimators that are biomechanically linked to weight-bearing, and especially those that are relatively insensitive to differences in locomotor style and phylogenetic history. Whenever possible, extant reference samples should be chosen to match target fossils in joint proportionality.

Quantification of the position and depth of the flexor hallucis longus groove in euarchontans, with implications for the evolution of primate positional behavior.

On the talus, the position and depth of the groove for the flexor hallucis longus tendon have been used to infer phylogenetic affinities and positional behaviors of fossil primates. This study quantifies aspects of the flexor hallucis longus groove (FHLG) to test if: (1) a lateral FHLG is a derived strepsirrhine feature, (2) a lateral FHLG reflects inverted and abducted foot postures, and (3) a deeper FHLG indicates a larger muscle. We used linear measurements of microCT-generated models from a sample of euarchontans (n = 378 specimens, 125 species) to quantify FHLG position and depth. Data are analyzed with ANOVA, Ordinary and Phylogenetic Generalized Least Squares, and Bayesian Ancestral State Reconstruction (ASR). Extant strepsirrhines, adapiforms, plesiadapiforms, dermopterans, and Ptilocercus exhibit lateral FHLGs. Extant anthropoids, subfossil lemurs, and Tupaia have medial FHLGs. FHLGs of omomyiforms and basal fossil anthropoids are intermediate between those of strepsirrhines and extant anthropoids. FHLG position has few correlations with pedal inversion features. Relative FHLG depth is not significantly correlated with body mass. ASRs support a directional model for FHLG position and a random walk model for FHLG depth. The prevalence of lateral FHLGs in many non-euprimates suggests a lateral FHLG is not a derived strepsirrhine feature. The lack of correlations with pedal inversion features suggests a lateral FHLG is not a sufficient indicator of strepsirrhine-like foot postures. Instead, a lateral FHLG may reduce the risk of tendon displacement in abducted foot postures on large diameter supports. A deep FHLG does not indicate a larger muscle, but likely reduces bowstringing during plantarflexion.

Patterns of dental emergence in early anthropoid primates from the Fayum Depression, Egypt

Paleontological field work in the Fayum Depression of Egypt has produced a remarkable diversity of fossil anthropoids, and this, combined with advances in genetic analyses of living anthropoids, has led to establishment of a temporal and phylogenetic framework for anthropoids that is achieving some degree of consensus. Less well understood are the evolutionary mechanisms and selective factors behind the origin and early diversification of anthropoids. One area that has remained under explored is investigation into the life history patterns of early anthropoids, a major omission given that understanding patterns of growth and development is essential for interpreting the paleobiology of fossil species. Here we detail dental emergence sequences for five species in four families of early anthropoid primates from the Fayum, and use these data to test Schultz’s Rule concerning the timing of emergence of molars versus premolars in mammals. Two important results are generated: (1) only one species had a dental eruption sequence identical to that observed among crown catarrhine primates; and (2) in all cases, the permanent canine was the last post-incisor dental element to fully erupt, a finding that may be significant for interpreting early anthropoid behavioral strategies.

Upper molar morphology of the early oligocene egyptian anthropoid Qatrania wingi.

Qatrania wingi is a poorly documented fossil anthropoid known only from Quarry E in the Jebel Qatrani Formation, Fayum Depression, Egypt. This report augments our knowledge of the dental morphology of Qatrania in order to clarify its phylogenetic relationships with other early African anthropoids. YPM 18008 from Quarry E is the first example of an upper molar fragment that can reasonably be assigned to Qatrania wingi. Maximum parsimony phylogenetic analyses incorporating the new data from YPM 18008 were performed. If YPM 18008 is treated as a separate OTU, it is reconstructed as a member of Qatraniinae (the parapithecid clade containing Qatrania and Apidium). The only qatraniine known to occur at Quarry E is Qatrania wingi, and YPM 18008 is allocated to this species based on its size, provenance, and morphology. Despite its small size and early stratigraphic occurrence, the upper molar morphology of Qatrania wingi is highly derived with respect to that of other parapithecids aside from Apidium. Like that of Apidium, the upper molar morphology of Qatrania bears multiple neomorphic cusps and cuspules. These features appear to be synapomorphies linking Apidium and Qatrania to the exclusion of other parapithecids for which upper molar morphology is known, namely Simonsius grangeri and Biretia spp. YPM 18008 supports the recent proposal of a Qatrania + Apidium clade within Parapithecidae. This conflicts with earlier hypotheses, in which Qatrania was reconstructed as being phylogenetically basal to a clade including the younger, larger-bodied parapithecid taxa Apidium, Parapithecus, and Simonsius.

Covariation Among Elements of the Bony Torso in Anthropoid Primates

A cornerstone assumption for reconstructing ape evolution is that the hominoid torso differs from that of monkeys, reflecting adaptation to below‐branch arboreality. The fossil record leaves only sporadic bony remains, however, forcing paleontologists to rely on hypothesized covariation among bones to infer torso structure. Recent data suggesting more variation within the torso than previously appreciated challenges long‐held assumptions used to make these inferences. To explore these associations, linear and landmark data were collected from vertebrae, sterna, ribs, pelves, clavicles, scapulae and humeri of 256 anthropoids. Also, intact torsos of 57 cadavers were CT scanned. Data reveal significant correlations among lumbar vertebral, lower rib, and iliac morphology. Correlations between upper and lower portions of the rib cage are weak, as are relations among ribs, pectoral girdle and humerus. Patterns of allometry also vary among regions. These results reflect differing selection pressures and structural constraints on parts of the torso, and provide data with which to more accurately infer aspects of torso form, and locomotor adaptation, in fossil anthropoids.

Incisor Crown Bending Strength Correlates With Diet and Incisor Curvature in Anthropoid Primates

Anthropoid incisors are large relative to the postcanine dentition and function in the preprocessing of food items. Previous analyses of anthropoid incisor allometry and shape demonstrate that incisor morphology is correlated with preferred foods and that more frugivorous anthropoids have larger and more curved incisors. Although the relationship between incisal crown curvature and preferred foods has been well documented in extant and fossil anthropoids, the functional significance of curvature variation has yet to be conclusively established. Given that an increase in crown curvature will increase maximum linear crown dimensions, and bending resistance is a function of linear crown dimensions, it is hypothesized that incisor crown curvature functons to increase incisor crown resistance to bending forces. This study uses beam theory to calculate the mesiodistal and labiolingual bending strengths of the maxillary and mandibular incisors of hominoid and platyrrhine taxa with differing diets and variable degrees of incisal curvature. Results indicate that bending strength correlates with incisal curvature and that frugivores have elevated incisor bending resistance relative to folivores. Maxillary central incisor bending strengths further discriminate platyrrhine and hominoid hard- and soft-object frugivores suggesting this crown is subjected to elevated occlusal loading relative to other incisors. These results are consistent with the hypothesis that incisor crown curvature functions to increase incisor crown resistance to bending forces but does not preclude the possibility that incisor bending strength is a composite function of multiple dentognathic variables including, but not limited to, incisor crown curvature.

Can morphological variables be used to predict hip joint function? An examination of the anthropoid proximal femur and range of abduction (919.10)

Femoral morphology is often been used to make inferences about hip mobility in fossil anthropoids, abduction ability in particular. However, no study has shown that variation in hip morphology is actually related to hip mobility. If hip joint mobility is predicted by morphological variation, this would provide a new tool to more specifically evaluate locomotor adaptation in fossils.We present results of an in silico model of anthropoid hip joint mobility that has been validated on a large sample of extant taxa (hominoids, cercopithecids, Ateles, Cebus). Pelves and femora of the same taxa were laser scanned and polygonal models were digitally articulated. Maximum hip abduction was modeled using PolyWorks software using strict morphological criteria for joint movement. Several morphologies of the femur that are hypothesized to relate to hip mobility were quantified from the laser scan data using PolyWorks. Regression was used to assess the relationship between morphologies and functional abilities.Neck‐shaft angle and femoral head orientation were significantly related to degree of abduction. However, the majority of morphologies quantified were not significant predictors of hip abduction ability, suggesting that many of the morphologies attributed to high joint mobility may not relate to increased abduction ability. This work has applications to reconstructing locomotor abilities in fossil anthropoids.Grant Funding Source: Study supported by NSF (BCS 1232393, 0647557, 0716244), Wenner Gren Foundation, LSB Leakey Foundatio

A new Late Eocene primate from the Krabi Basin (Thailand) and the diversity of Palaeogene anthropoids in southeast Asia

According to the most recent discoveries from the Middle Eocene of Myanmar and China, anthropoid primates originated in Asia rather than in Africa, as was previously considered. But the Asian Palaeogene anthropoid community remains poorly known and inadequately sampled, being represented only from China, Myanmar, Pakistan and Thailand. Asian Eocene anthropoids can be divided into two distinct groups, the stem group eosimiiforms and the possible crown group amphipithecids, but the phylogenetic relationships between these two groups are not well understood. Therefore, it is critical to understand their evolutionary history and relationships by finding additional fossil taxa. Here, we describe a new small-sized fossil anthropoid primate from the Late Eocene Krabi locality in Thailand, Krabia minuta, which shares several derived characters with the amphipithecids. It displays several unique dental characters, such as extreme bunodonty and reduced trigon surface area, that have never been observed in other Eocene Asian anthropoids. These features indicate that morphological adaptations were more diversified among amphipithecids than was previously expected, and raises the problem of the phylogenetic relations between the crown anthropoids and their stem group eosimiiforms, on one side, and the modern anthropoids, on the other side.

On the holotype and original description of the pliopithecid Plesiopliopithecus lockeri ( )

Pliopithecoids are a diverse group of Miocene catarrhine primates from Eurasia. Their positional behavior is still unknown, and many species are known exclusively from dentognathic remains. Here, we describe a proximal radius (IPS66267) from the late Miocene of Castell de Barberà (Vallès-Penedès Basin, NE Iberian Peninsula) that represents the first postcranial specimen of the pliopithecoid Barberapithecus huerzeleri. A body mass estimate based on the radius is compared with dental estimates, and its morphology is compared with that of extant and fossil anthropoids by qualitative means as well as by landmark-based three-dimensional geometric morphometrics. The estimated body mass of ∼5 kg for IPS66267 closely matches the dental estimates for the (female) holotype, thereby discounting an alternative attribution to the large-bodied hominoid recorded at Castell de Barberà. In multiple features (oval and moderately tilted head with a pronounced lateral lip and a restricted articular area for the capitulum; proximodistally expanded proximal radioulnar joint; and short, robust, and anteroposteriorly compressed neck), the specimen differs from hominoids and resembles instead extant nonateline monkeys and stem catarrhines. The results of the morphometric analysis further indicate that the Barberapithecus proximal radius shows closer similarities with nonsuspensory arboreal cercopithecoids and the dendropithecid Simiolus. From a locomotor viewpoint, the radius of Barberapithecus lacks most of the features functionally related to climbing and/or suspensory behaviors and displays instead a proximal radioulnar joint that would have been particularly stable under pronation. On the other hand, the Barberapithecus radius differs from other stem catarrhines in the less anteroposteriorly compressed and less tilted radial head with a deeper capitular fovea, suggesting a somewhat enhanced mobility at the elbow joint. We conclude that pronograde arboreal quadrupedalism was the main component of the locomotor repertoire of Barberapithecus but that, similar to other crouzeliids, it might have displayed better climbing abilities than pliopithecids.

Preliminary notes on a newly discovered skull of the extinct monkey Antillothrix from Hispaniola and the origin of the Greater Antillean monkeys

Body mass is an important component of any paleobiological reconstruction. Reliable skeletal dimensions for making estimates are desirable but extant primate reference samples with known body masses are rare. We estimated body mass in a sample of extinct platyrrhines and Fayum anthropoids based on four measurements of the articular surfaces of the humerus and femur. Estimates were based on a large extant reference sample of wild-collected individuals with associated body masses, including previously published and new data from extant platyrrhines, cercopithecoids, and hominoids. In general, scaling of joint dimensions is positively allometric relative to expectations of geometric isometry, but negatively allometric relative to expectations of maintaining equivalent joint surface areas. Body mass prediction equations based on articular breadths are reasonably precise, with %SEEs of 17–25%. The breadth of the distal femoral articulation yields the most reliable estimates of body mass because it scales similarly in all major anthropoid taxa. Other joints scale differently in different taxa; therefore, locomotor style and phylogenetic affinity must be considered when calculating body mass estimates from the proximal femur, proximal humerus, and distal humerus. The body mass prediction equations were applied to 36 Old World and New World fossil anthropoid specimens representing 11 taxa, plus two Haitian specimens of uncertain taxonomic affinity. Among the extinct platyrrhines studied, only Cebupithecia is similar to large, extant platyrrhines in having large humeral (especially distal) joints. Our body mass estimates differ from each other and from published estimates based on teeth in ways that reflect known differences in relative sizes of the joints and teeth. We prefer body mass estimators that are biomechanically linked to weight-bearing, and especially those that are relatively insensitive to differences in locomotor style and phylogenetic history. Whenever possible, extant reference samples should be chosen to match target fossils in joint proportionality.

Variation in the Morphology of the Maxillary Sinus among Anthropoids and Its Potential for Phylogenetic Analyses

The maxillary sinus communicates with the middle meatus of the nasal cavity through a narrow ostium. Here, I have surveyed variations in the maxillary sinus anatomy of extant and fossil anthropoids which have been examined using computed tomography (CT). The CT studies have identi.ed the sinus by its ostium that opens exclusively to the middle nasal meatus, because the ostium marks site from which the pneumatization to form the sinus begins. A sinus pneumatizing the entire maxilla is shared by all extant hominoids. In contrast, cancellous bone completely .lls the maxilla in extant cercopithecoids, with the exception of macaque monkeys which have a small sinus. Among platyrrhines, the entire maxilla is pneumatized by the sinus in the Atelidae, Cebus, and Callicebus, whereas only the medial part of the maxilla is pneumatized by the sinus in the Callitrichinae and Aotus. Pithecia exhibits a unique conformation in which the maxillary sinus and another cavity expands from the inferior meatus pneumatize the posteromedial and anterolateral parts of the entire maxilla, respectively. Saimiri has no sinus, as in the case of cercopithecoids excluding macaques. In Chiropotes and maybe Cacajao, the inferior meatus expands into the area between the middle meatus and medial surface of the maxilla thereby disturbing sinus formation. The sinus was lost independently in Saimiri and Cacajao-Chiropotes clades, and in the common ancestor of cercopithecoids. The sinus pneumatizing the entire maxilla is argued to be a primitive feature in anthropoids. This hypothesis is supported by the results from studies of fossil anthropoids. This information may be relevant to the phylogenetic analyses of unclassi.ed fossil anthropoids. I hope this paper will also stimulate future studies on the variations in sinus anatomy in prosimians and other mammals, and on other inner structures of the cranium in primates. Potentially, such information probably will further facilitate the phylogenetic analyses of fossil specimens.

The Oreopithecus thumb: a strange case in hominoid evolution

Pliopithecoids are a diverse group of Miocene catarrhine primates from Eurasia. Their positional behavior is still unknown, and many species are known exclusively from dentognathic remains. Here, we describe a proximal radius (IPS66267) from the late Miocene of Castell de Barberà (Vallès-Penedès Basin, NE Iberian Peninsula) that represents the first postcranial specimen of the pliopithecoid Barberapithecus huerzeleri. A body mass estimate based on the radius is compared with dental estimates, and its morphology is compared with that of extant and fossil anthropoids by qualitative means as well as by landmark-based three-dimensional geometric morphometrics. The estimated body mass of ∼5 kg for IPS66267 closely matches the dental estimates for the (female) holotype, thereby discounting an alternative attribution to the large-bodied hominoid recorded at Castell de Barberà. In multiple features (oval and moderately tilted head with a pronounced lateral lip and a restricted articular area for the capitulum; proximodistally expanded proximal radioulnar joint; and short, robust, and anteroposteriorly compressed neck), the specimen differs from hominoids and resembles instead extant nonateline monkeys and stem catarrhines. The results of the morphometric analysis further indicate that the Barberapithecus proximal radius shows closer similarities with nonsuspensory arboreal cercopithecoids and the dendropithecid Simiolus. From a locomotor viewpoint, the radius of Barberapithecus lacks most of the features functionally related to climbing and/or suspensory behaviors and displays instead a proximal radioulnar joint that would have been particularly stable under pronation. On the other hand, the Barberapithecus radius differs from other stem catarrhines in the less anteroposteriorly compressed and less tilted radial head with a deeper capitular fovea, suggesting a somewhat enhanced mobility at the elbow joint. We conclude that pronograde arboreal quadrupedalism was the main component of the locomotor repertoire of Barberapithecus but that, similar to other crouzeliids, it might have displayed better climbing abilities than pliopithecids.

Primate postcrania from the late middle Eocene of Myanmar.

Fossil primates have been known from the late middle to late Eocene Pondaung Formation of Myanmar since the description of Pondaungia cotteri in 1927. Three additional primate taxa, Amphipithecus mogaungensis, Bahinia pondaungensis and Myanmarpithecus yarshensis, were subsequently described. These primates are represented mostly by fragmentary dental and cranial remains. Here we describe the first primate postcrania from Myanmar, including a complete left humerus, a fragmentary right humerus, parts of left and right ulnae, and the distal half of a left calcaneum, all representing one individual. We assign this specimen to a large species of Pondaungia based on body size and the known geographic distribution and diversity of Myanmar primates. Body weight estimates of Pondaungia range from 4,000 to 9,000 g, based on humeral length, humeral midshaft diameter, and tooth area by using extant primate regressions. The humerus and ulna indicate that Pondaungia was capable of a wide variety of forelimb movements, with great mobility at the shoulder joint. Morphology of the distal calcaneus indicates that the hind feet were mobile at the transverse tarsal joint. Postcrania of Pondaungia present a mosaic of features, some shared in common with notharctine and adapine adapiforms, some shared with extant lorises and cebids, some shared with fossil anthropoids, and some unique. Overall, Pondaungia humeral and calcaneal morphology is most consistent with that of other known adapiforms. It does not support the inclusion of Pondaungia in Anthropoidea.

Into the Light: The Origin of Anthropoidea

▪ Abstract Anthropoidea is a clade of primates including Platyrrhini and Catarrhini. Definitive fossil anthropoids include the early Oligocene Propliopithecidae and the late Eocene–early Oligocene Parapithecidae and Oligopithecidae. Middle Eocene Eosimiidae are probable fossil anthropoids from Asia. Relationships of anthropoids to other primates are debated, although parsimony argues for a tarsier-anthropoid clade (Haplorhini) arising within omomyiforms. Distinctive features of the anthropoid visual system related to diurnality include highly convergent orbits, small corneal diameter/posterior nodal distance, high concentrations of cones and ganglion cells, and extreme magnification of foveal and parafoveal regions of the visual field in the visual cortex. Anthropoid origins was associated with a shift from a nocturnal visually predatory ancestor to diurnal visual predation at small body size (<100 g). This shift may have occurred in the stem lineage of the tarsier-anthropoid clade. The early anthropoids were insectivore-frugivores with unfused mandibular symphyses, small brains, and either dichromatic or trichromatic vision. The evolution of larger brains, symphyseal fusion, and definitive trichromacy occurred later in anthropoid evolution.