Systematics of early and middle Miocene Old World monkeys.

New information about the early cercopithecoids Prohylobates tandyi (Wadi Moghra, Egypt) and Prohylobates sp. indet. (Buluk and Nabwal, Kenya) is presented. Comparisons are made among all major collections of Early and Middle Miocene catarrhine monkeys, and a systematic revision of the early Old World monkeys is provided. Previous work involving the systematics of early Old World monkeys (Victoriapithecidae; Cercopithecoidea) has been hampered by a number of factors, including the poor preservation of Prohylobates material from North Africa and lack of comparable anatomical parts across collections. However, it is now shown that basal cercopithecoid species from both northern and eastern Africa can be distinguished from one another on the basis of degree of lower molar bilophodonty, relative lower molar size, occlusal details, symphyseal construction, and mandibular shape. Results of particular interest include: 1) the first identification of features that unambiguously define Prohylobates relative to Victoriapithecus; 2) confirmation that P. tandyi is incompletely bilophodont; and 3) recognition of additional victoriapithecid species.

Dental microwear texture analysis of two families of subfossil lemurs from Madagascar.

This study employs dental microwear texture analysis to reconstruct the diets of two families of subfossil lemurs from Madagascar, the archaeolemurids and megaladapids. This technique is based on three-dimensional surface measurements utilizing a white-light confocal profiler and scale-sensitive fractal analysis. Data were recorded for six texture variables previously used successfully to distinguish between living primates with known dietary differences. Statistical analyses revealed that the archaeolemurids and megaladapids have overlapping microwear texture signatures, suggesting that the two families occasionally depended on resources with similar mechanical properties. Even so, moderate variation in most attributes is evident, and results suggest potential differences in the foods consumed by the two families. The microwear pattern for the megaladapids indicates a preference for tougher foods, such as many leaves, while that of the archaeolemurids is consistent with the consumption of harder foods. The results also indicate some intraspecific differences among taxa within each family. This evidence suggests that the archaeolemurids and megaladapids, like many living primates, likely consumed a variety of food types.

The hands and feet of Archaeolemur: metrical affinities and their functional significance.

Recent expeditions to Madagascar have recovered abundant skeletal remains of Archaeolemur, one of the so-called "monkey lemurs" known from Holocene deposits scattered across the island. These new skeletons are sufficiently complete to permit reassembly of entire hands and feet--postcranial elements crucial to drawing inferences about substrate preferences and positional behavior. Univariate and multivariate analysis of intrinsic hand and foot proportions, phalangeal indices, relative pollex and hallux lengths, phalangeal curvature, and distal phalangeal shape reveal a highly derived and unique morphology for an extinct strepsirrhine that diverges dramatically from that of living lemurs and converges in some respects on that of Old World monkeys (e.g., mandrills, but not baboons or geladas). The hands and feet of Archaeolemur are relatively short (extremely so relative to body size); the carpus and tarsus are both "long" relative to total hand and foot lengths, respectively; phalangeal indices of both the hands and feet are low; both pollex and hallux are reduced; the apical tufts of the distal phalanges are very broad; and the proximal phalanges are slightly curved (but more so than in baboons). Overall grasping capabilities may have been compromised to some extent, and dexterous handling of small objects seems improbable. Deliberate and noncursorial quadrupedalism was most likely practiced on both the ground and in the trees. A flexible locomotor repertoire in conjunction with a eurytopic trophic adaptation allowed Archaeolemur to inhabit much of Madagascar and may explain why it was one of the latest surviving subfossil lemurs.

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.

The cranium of Parapithecus grangeri, an Egyptian Oligocene anthropoidean primate.

A nearly complete skull of Parapithecus grangeri from the early Oligocene of Egypt is described. The specimen is relatively undistorted and is undoubtedly the most complete higher primate skull yet found in the African Oligocene, which also makes it the most complete Oligocene primate cranium worldwide. Belonging in superfamily Parapithecoidea, a group regarded by some as the sister group to all other Anthropoidea, this skull reveals important information about the radiation of stem anthropoideans. This cranium is about 15% larger than size estimates based on a fragmentary cranium of its contemporary and close relative Apidium phiomense. It is about the same size as that of the gray gentle lemur, Hapalemur griseus, or of platyrrhines such as the owl monkey, Aotus trivirgatus, or the titi monkey, Callicebus torquatus. Comparatively small orbits and size differences in jaws and teeth show it was both diurnal and dimorphic. This is the only specimen of the species that shows (from sockets) that there were four small upper incisors. Several mandibular specimens of the species establish that there were no permanent lower incisors and that the symphysis was fused. Like other early anthropoideans this species possessed a lower encephalization quotient and less-developed orbital frontality than later anthropoideans. There is full postorbital closure and fusion of the metopic suture, and the ectotympanic forms a rim to the auditory aperture. A probable frontal/alisphenoid contact is a potentially derived resemblance to Catarrhini. A proposed separate genus for the species P. grangeri is not sustained.

Diets of fossil primates from the Fayum Depression of Egypt: a quantitative analysis of molar shearing.

Over the last 90 years, Eocene and Oligocene aged sediments in the Fayum Depression of Egypt have yielded at least 17 genera of fossil primates. However, of this diverse sample the diets of only four early Oligocene anthropoid genera have been previously studied using quantitative methods. Here we present dietary assessments for 11 additional Fayum primate genera based on the analysis of body mass and molar shearing crest development. These studies reveal that all late Eocene Fayum anthropoids were probably frugivorous despite marked subfamilial differences in dental morphology. By contrast, late Eocene Fayum prosimians demonstrated remarkable dietary diversity, including specialized insectivory (Anchomomys), generalized frugivory (Plesiopithecus), frugivory+insectivory (Wadilemur), and strict folivory (Aframonius). This evidence that sympatric prosimians and early anthropoids jointly occupied frugivorous niches during the late Eocene reinforces the hypothesis that changes in diet did not form the primary ecological impetus for the origin of the Anthropoidea. Early Oligocene Fayum localities differ from late Eocene Fayum localities in lacking large-bodied frugivorous and folivorous prosimians, and may document the first appearance of primate communities with trophic structures like those of extant primate communities in continental Africa. A similar change in primate community structure during the Eocene-Oligocene transition is not evident in the Asian fossil record. Putative large anthropoids from the Eocene of Asia, such as Amphipithecus mogaungensis, Pondaungia cotteri, and Siamopithecus eocaenus, share with early Oligocene Fayum anthropoids derived features of molar anatomy related to an emphasis on crushing and grinding during mastication. However, these dental specializations are not seen in late Eocene Fayum anthropoids that are broadly ancestral to the later-occurring anthropoids of the Fayum's upper sequence. This lack of resemblance to undisputed Eocene African anthropoids suggests that the "progressive" anthropoid-like dental features of some large-bodied Eocene Asian primates may be the result of dietary convergence rather than close phyletic affinity with the Anthropoidea.

Earliest record of a parapithecid anthropoid from the Jebel Qatrani formation, Northern Egypt.

A fifth anthropoid (= anthropoidean, simian or simiiform) genus and species from the late Eocene Fayum Quarry L-41, Abuqatrania basiodontos gen. et sp. nov., further augments the already remarkable primate diversity from this locality and provides the first convincing extension of the enigmatic family Parapithecidae into the oldest productive vertebrate fossil-bearing stratum of the Jebel Qatrani Formation. A. basiodontos exhibits no clear autapomorphies nor any apomorphies that are shared exclusively with any other parapithecid species, and it is most parsimoniously interpreted as the sister taxon of a Qatrania-Parapithecus-Apidium clade. Reevaluation of two contemporaries of A. basiodontos, Serapia and Arsinoea, suggests that neither genus should be ranked as a basal parapithecid. Serapia is more derived than primitive parapithecids in the morphology of the lower fourth premolar and exhibits greater overall similarity to Proteopithecus in cusp placement and the shape and proportions of its lower teeth; accordingly, we place Serapia in the family Proteopithecidae. Arsinoea is much more problematic and does not fit well with any hitherto known Afro-Arabian anthropoid group; we place this genus in a new anthropoid family, Arsinoeidae.

Adaptive and phylogenetic significance of ontogenetic sequences in Archaeolemur, subfossil lemur from Madagascar.

Among the best known of recently extinct Malagasy lemurs is Archaeolemur, which is represented by many hundreds of specimens. The phylogenetic affinities of this taxon are unclear, especially in light of recent preliminary analysis of ancient DNA which does not support its previously accepted close relationship with the living Indridae. We examined the nearly complete skeletons of two adults and one juvenile and other less complete specimens to reconstruct aspects of the ontogeny of Archaeolemur. To compare the development of Archaeolemur to that of living strepsirrhines we collected data on Propithecus verreauxi, Eulemur fulvus, and Lemur catta. Additionally, because Archaeolemur exhibits some morphological convergences with distantly related papionins, we tested for convergence in the developmental patterns of Archaeolemur and Macaca fascicularis. Data include the status of tooth eruption, craniofacial sutural closure, and postcranial epiphyseal fusion, as well as linear measurements. We used discriminant function analysis and other tools to explore ontogenetic similarities and differences. The adaptive and phylogenetic significance of ontogenetic information is discussed. Our analysis shows that Archaeolemur displays a clear strepsirrhine pattern of development with only minor macaque convergences. Among the Strepsirrhini, Archaeolemur is slightly more similar developmentally to E. fulvus and L. catta than to P. verreauxi. Some of the distinctive features of the ontogeny of Archaeolemur may be related to diet, while others bear apparent testimony to a relatively rapid absolute pace of growth and development.

Astragalar morphology of late Eocene anthropoids from the Fayum Depression (Egypt) and the origin of catarrhine primates.

The phylogenetic relationships of the late Eocene anthropoids Catopithecus browni and Proteopithecus sylviae are currently a matter of debate, with opinion divided as to whether these taxa are stem or crown anthropoids. The phylogenetic position of Catopithecus is of particular interest, for, unlike the highly generalized genus Proteopithecus, this taxon shares apomorphic dental and postcranial features with more derived undoubted catarrhines that appear in the same region 1-2 Ma later. If these apomorphies are homologous and Catopithecus is a stem catarrhine, the unique combination of plesiomorphic and apomorphic features preserved in this anthropoid would have important implications for our understanding of the crown anthropoid morphotype and the pattern of morphological character transformations that occurred during the early phases of stem catarrhine evolution.Well-preserved astragali referrable to Proteopithecus, Catopithecus, and the undoubted early Oligocene stem catarrhine Aegyptopithecus have provided additional morphological evidence that allows us to further evaluate competing hypotheses of interrelationships among Eocene-Oligocene Afro-Arabian anthropoids. Qualitative observations and multivariate morphometric analyses reveal that the astragalar morphology of Proteopithecus is very similar to that of early Oligocene parapithecids and living and extinct small-bodied platyrrhines, and strengthens the hypothesis that the morphological pattern shared by these taxa is primitive within crown Anthropoidea. In contrast, Catopithecus departs markedly from the predicted crown anthropoid astragalar morphotype and shares a number of apomorphic features (e.g., deep cotylar fossa, laterally projecting fibular facet, trochlear asymmetry, mediolaterally wide astragalar head) with Aegyptopithecus and Miocene-Recent catarrhines. The evidence from the astragalus complements other independent data from the dentition, humerus and femur of Catopithecus that support this taxon's stem catarrhine status, and we continue to maintain that oligopithecines are stem catarrhines that constitute the sister group of a clade containing propliopithecines and Miocene-Recent catarrhines.

Anthropoid humeri from the late Eocene of Egypt.

A number of recent studies have, by necessity, placed a great deal of emphasis on the dental evidence for Paleogene anthropoid interrelationships, but cladistic analyses of these data have led to the erection of phylogenetic hypotheses that appear to be at odds with biogeographic and stratigraphic considerations. Additional morphological data from the cranium and postcranium of certain poorly understood Paleogene primates are clearly needed to help test whether such hypotheses are tenable. Here we describe humeri attributable to Proteopithecus sylviae and Catopithecus browni, two anthropoids from late Eocene sediments of the Fayum Depression in Egypt. Qualitative and morphometric analyses of these elements indicate that humeri of the oligopithecine Catopithecus are more similar to early Oligocene propliopithecines than they are to any other Paleogene anthropoid taxon, and that Proteopithecus exhibits humeral similarities to parapithecids that may be symplesiomorphies of extant (or "crown") Anthropoidea. The humeral morphology of Catopithecus is consistent with certain narrowly distributed dental apomorphies-such as the loss of the upper and lower second premolar and the development of a honing blade for the upper canine on the lower third premolar-which suggest that oligopithecines constitute the sister group of a clade containing propliopithecines and Miocene-Recent catarrhines and are not most closely related to Proteopithecus as has recently been proposed.

New wrist bones of the Malagasy giant subfossil lemurs.

Recently discovered wrist bones of the Malagasy subfossil lemurs Babakotia radofilai, Palaeopropithecus ingens, Mesopropithecus dolichobrachion, and Megaladapis madagascariensis shed new light on the postcranial morphologies and positional behaviors that characterized these extinct primates. Wrist bones of P. ingens resemble those of certain modern hominoids in having a relatively enlarged ulnar head and dorsally extended articular surface on the hamate, features related to a large range of rotation at the inferior radioulnar and midcarpal joints. The scaphoid of P. ingens is also similar to that of the extant tree sloth Choloepus in having an elongate, palmarly directed tubercle forming a deep radial margin of the carpal tunnel for the passage of large digital flexors. In contrast, wrist remains of Megaladapis edwardsi and M. madagascariensis exhibit traits observed in the hands of extant pronograde, arboreal primates; these include a dorsopalmarly expanded pisiform and well-developed "spiral" facet on the hamate. Moreover, Megaladapis spp. and Mesopropithecus dolichobrachion possess bony tubercles (e.g., scaphoid tubercle and hamate hamulus) forming the carpal tunnel that are relatively similar in length to those of modern pronograde lemurs. Babakotia and Mesopropithecus differ from Megaladapis in exhibiting features of the midcarpal joint related to frequent supination and radioulnar deviation of the hand characteristic of animals that use vertical and quadrumanous climbing in their foraging behaviors. Comparative analysis of subfossil lemur wrist morphology complements and expands upon prior inferences based on other regions of the postcranial skeleton, and suggests a considerable degree of locomotor and postural heterogeneity among these recently extinct primates.

Widanelfarasia, a diminutive placental from the late Eocene of Egypt.

The lower dentition of Widanelfarasia (new genus), a diminutive late Eocene placental from the Fayum Depression in Egypt, is described. Widanelfarasia exhibits a complex of features associated with incipient zalambdodonty and at least three unequivocal apomorphies [loss of P(1), an enlarged I(2) (relative to I(3)), and a basal cusp on I(2)], which provide weak support for its placement as a possible sister taxon of either a tenrecid-chrysochlorid clade or of solenodontids. The former hypothesis gains additional support from biogeographical evidence, but both scenarios are currently tenuous as Widanelfarasia is clearly not truly zalambdodont. Phylogenetic hypotheses positing affinities with tenrecids alone or chrysochlorids alone must invoke either convergent acquisition of zalambdodonty in these taxa or autapomorphic reversal in Widanelfarasia. Given these considerations, a relationship with more generalized taxa from the Laurasian Paleogene (e.g., geolabidids, nyctitheriids, leptictids) cannot yet be ruled out. Comparisons with other Paleogene Afro-Arabian forms are generally inconclusive. A relationship with the earlier Eocene Chambilestes from Tunisia-currently represented by a single specimen preserving P(4)-M(3)-seems possible based on the geometry and predicted occlusal relationships of these teeth, but cannot be confidently determined until these two taxa come to be represented by common diagnostic elements. Todralestes (late Paleocene, Morocco) exhibits general phenetic similarities to Widanelfarasia, but it is not yet known whether this taxon shares any of Widanelfarasia's unequivocal dental apomorphies. Pending the recovery of more informative material, we tentatively refer Widanelfarasia to Placentalia incertae sedis. Truly zalambdodont placentals remain conspicuously absent from the Paleogene of Afro-Arabia.

The widely conserved Era G-protein contains an RNA-binding domain required for Era function in vivo.

Era is a small G-protein widely conserved in eubacteria and eukaryotes. Although essential for bacterial growth and implicated in diverse cellular processes, its actual function remains unclear. Several lines of evidence suggest that Era may be involved in some aspect of RNA biology. The GTPase domain contains features in common with all G-proteins and is required for Era function in vivo. The C-terminal domain (EraCTD) bears scant similarity to proteins outside the Era subfamily. On the basis of sequence comparisons, we argue that the EraCTD is similar to, but distinct from, the KH RNA-binding domain. Although both contain the consensus VIGxxGxxI RNA-binding motif, the protein folds are probably different. We show that bacterial Era binds RNA in vitro and can form higher-order RNA-protein complexes. Mutations in the VIGxxGxxI motif and other conserved residues of the Escherichia coli EraCTD decrease RNA binding in vitro and have corresponding effects on Era function in vivo, including previously described effects on cell division and chromosome partitioning. Importantly, mutations in L-66, located in the predicted switch II region of the E. coli Era GTPase domain, also perturb binding, leading us to propose that the GTPase domain regulates RNA binding in response to unknown cellular cues. The possible biological significance of Era RNA binding is discussed.

Canine sexual dimorphism in Egyptian Eocene anthropoid primates: Catopithecus and Proteopithecus.

Two very small late Eocene anthropoid primates, Catopithecus browni and Proteopithecus sylviae, from Fayum, Egypt show evidence of substantial sexual dimorphism in canine teeth. The degree of dimorphism suggests that these early anthropoids lived in social groups with a polygynous mating system and intense male-male competition. Catopithecus and Proteopithecus are smaller in estimated body size than any living primates showing canine dimorphism. The origin of canine dimorphism and polygyny in anthropoids was not associated with the evolution of large body size.

Tarsier-like locomotor specializations in the oligocene primate afrotarsius.

Tarsiers and extinct tarsier-like primates have played a central role in views of primate phylogeny and evolution for more than a century. Because of the importance of tarsiers in so many primatological problems, there has been particular interest in questions about the origin of tarsier specializations and the biogeography of early tarsioid radiations. We report on a new fossil of rare Afrotarsius that shows near identity to modern Tarsius in unique specializations of the leg, which provides information about the locomotor behavior and clarifies the phylogenetic position of this previously controversial primate. These specializations constitute evidence that Afrotarsius is a tarsiid, closely related to extant Tarsius; hence, it is now excluded from being a generalized sister taxon to Anthropoidea.

An upper dentition of Aframonius dieides (Primates) from the Fayum, Egyptian Eocene.

The first known upper dentitions--an adult and subadult--of the cercamoniine adapiform Aframonius dieides are described. Comparisons show that A. dieides has an upper molar morphology resembling that of other cercamoniine adapids but the species lacks some of their typical specializations. The new dental material confirms that Aframonius stands closer to Mahgarita from west Texas and Cercamonius from Europe than it does to Schizarodon and Omanodon from Oman-all of which have been ranked as cercamoniines. Affinities of the latter two genera probably lie with the Anchomomys group. The presence of a cercamoniine adapid in the Eocene of Egypt supports the view that early African anthropoideans evolved not in isolation, but concomitantly with a contemporary Eocene prosimian radiation.

Discovery of the smallest Fayum Egyptian primates (Anchomomyini, Adapidae).

Two new adapiform primate species from locality 41, Jebel Qatrani Formation, Egypt, are described. The first, here named Wadilemur elegans genus novum species novum (holotype Cairo Geological Museum 42211), consists of a right mandible with P3-M3. The second is assigned to Anchomomys milleri species novum, with a holotype Cairo Geological Museum 42842, that includes the right mandible with lower canine to M3. Both species are allied closely with genera that are known to be from Eocene deposits either in Europe, Tunisia, or the Sultanate of Oman (Arabia), thus enhancing earlier paleomagnetic evidence that locality 41 was deposited in Eocene times.

Dentition of Proteopithecus sylviae, an archaic anthropoid from the Fayum, Egypt.

Proteopithecus sylviae is an archaic anthropoid from the late Eocene quarry L-41, Fayum Province, Egypt. The dentition of Proteopithecus is very primitive and does not closely resemble that of other, better known, primates from the Fayum (e.g., parapithecids and propliopithecids). The dental morphology, much of which is described herein, shows a platyrrhine-like level of organization, suggesting that P. sylviae may occupy a position near the base of the modern anthropoid radiation.

Preliminary description of the cranium of Proteopithecus sylviae, an Egyptian late Eocene anthropoidean primate.

Recent discovery of crania, dentitions, and postcrania of a primitive anthropoidean primate, Proteopithecus sylviae, at the late Eocene L-4l quarry in the Fayum, Egypt, provides evidence of a new taxonomic family of early African higher primates, the Proteopithecidae. This family could be part of the basal radiation that produced the New World platyrrhine primates, or it could be unrelated to any subsequent lineages. Although no larger than a small callitrichid or a dwarf lemur, this tiny primate already possessed many of the derived features of later anthropoids and was a diurnal and probably dimorphic species. In dental formula and other dental proportions, as well as in known postcranial features, Proteopithecus more nearly resembles platyrrhines than does any other Old World higher primate. The small size of the Proteopithecus cranium demonstrates that the defining cranial characteristics of Anthropoidea did not arise as a consequence of an increase in size during derivation from earlier prosimians.