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Primates Linnaeus, 1758 Haplorhini Pocock, 1918 Tarsiiformes Gregory, 1915 Archicebidae fam. nov. Archicebus achilles gen. et sp. nov. Etymology. Generic name is derived from arche, Greek for beginning, and cebus, [...], Reconstructing the earliest phases of primate evolution has been impeded by gaps in the fossil record, so that disagreements persist regarding the paleobiology and phylogenetic relationships of the earliest primates. Here we report the discovery of a nearly complete and partly articulated skeleton of a primitive haplorhine primate from the early Eocene of China, about 55 million years ago, the oldest fossil primate of this quality ever recovered. Coupled with detailed morphological examination using propagation phase contrast X-ray synchrotron microtomography, our phylogenetic analysis based on total available evidence indicates that this fossil is the most basal known member of the tarsiiform clade. In addition to providing further support for an early dichotomy between the strepsirrhine and haplorhine clades, this new primate further constrains the age of divergence between tarsiiforms and anthropoids. It also strengthens the hypothesis that the earliest primates were probably diurnal, arboreal and primarily insectivorous mammals the size of modern pygmy mouse lemurs.

The phylogenetic affinities of the primates of the late middle Eocene Pondaung Formation of Myanmar have long been disputed. The discovery of the NMMP 39 talus (Marivaux et al.: Proc Natl Acad Sci USA 100 (2003) 13173-13178) provided the first clear evidence from the postcranium that a relatively large-bodied haplorhine primate is represented in the Pondaung fauna. Another talus (NMMP 82; Marivaux et al., 2010). Talar morphology, phylogenetic affinities and locomotor adaptation of a large-bodied amphipithecid primate from the late middle Eocene of Myanmar, Am J Phys Anthropol DOI: 10.1002/ajpa.21307) has been recently recovered which also pertains to Haplorhini. The metric and nonmetric features supporting the hypothesis of anthropoid affinities for NMMP 39 have been criticized by Gunnell and Ciochon (Gunnell GF, Ciochon RL. 2008. Revisiting primate postcrania from the Pondaung Formation of Myanmar. In: Fleagle JG, Gilbert CC, editors. Elwyn Simons: a search for origins. New York: Springer. p 211-228). Their analysis, how ever, was based on a very limited choice of variables, taxa, and individuals. Based on an extended sample, we are able to produce both principal components and discriminant functions that yield a rather clear separation of extant haplorhine and strepsirhine tali. Both principal components and discriminant function scores of the Pondaung tali fall with those of haplorhine primates. In addition, the Pondaung tali lack all the derived nonmetric features characteristic of strepsirhine primates, but exhibit all the features characteristic of haplorhine primates. We dispute the features Gunnell and Ciochon (2008) claim are uniquely shared by the Pondaung tali and adapiforms. Their rejection of the phylogenetic significance of the features shared by these tall and haplorhines is unwarranted by the evidence. Based on both metric and nonmetric features, the Pondaung tali are structurally most similar to the tali of haplorhines, particularly anthropoids. Am J Phys Anthropol 143:223-234, 2010. o2010 Wiley-Liss, Inc. KEY WORDS talus; strepsirhine; haplorhine; anthropoid; Amphipithecidae DOI 10.1002/ajpa.21308

A well-preserved fossil talus [National Museum of Myanmar Primates (NMMP) 82] of a large-bodied primate is described from the late middle Eocene Pondaung Formation of central Myanmar. The specimen was collected at Thandaung Kyitchaung, a well-known amphipithecid primate--bearing locality near the village of Mogaung. NMMP 82 adds to a meager but growing sample of postcranial remains documenting the large-bodied primates of the Pondaung Formation. This new talus exhibits a suite of features that resemble conditions found in living and fossil haplorhine primates, notably anthropoids. As such, the phylogenetic signal deriving from the morphology of NMMP 82 conflicts with that provided by NMMP 20, a partial skeleton (including a fragmentary calcaneus) of a second large-bodied Pondaung primate showing undoubted adapiform affinities. Analysis subtalar joint compatibility in a hypothetical NMMP 82/NMMP 20 combination (talus/calcaneus) reveals a substantial degree of functional mismatch between these two tarsal bones. The functional incongruence in subtalar joint morphology between NMMP 20 and NMMP 82 is consistent with the seemingly divergent phylogenetic affinities of these specimens, indicating that two higher level taxa of relatively large-bodied primates are documented in the Pondaung Formation. On the basis of its size and morphology, we refer the NMMP 82 talus to the large-bodied amphipithecid Pondaungia. The occurrence of anthropoid-like tali in the Pondaung Formation obviates the need to invoke homoplasy to explain the shared, derived dental characters that are common to amphipithecids and undoubted anthropoids. Functionally, the NMMP 82 talus appears to have pertained to a primate that is engaged in active quadrupedalism in an arboreal environment along broad and subhorizontal branches. The primate taxon represented by NMMP 82 was capable of climbing and leaping, although it was not particularly specialized for either of these activities. Am J Phys Anthropol 143:208-222, 2010. [c] 2010 Wiley-Liss, Inc. KEY WORDS South Asia; Pondaung; phylogeny; anthropoid; functional anatomy DOI 10.1002/ajpa.21307

The foot, perhaps more than any other region of the primate body, reflects the interaction of positional behaviors with the geometric properties of available supports. The ability to reverse the hind foot during hindlimb suspension while hanging from a horizontal support or descending a large diameter vertical trunk has been noted in many arboreal mammals, including primates. Observations of Varecia variegata in the wild and under seminatural conditions document hindlimb suspension in this lemurid primate. The kinematics and skeletal correlates of this behavior are examined. Analogy is made with the form and function exhibited by nonprimate mammalian taxa employing this behavior. Examples of carnivores and rodents display very similar adaptations of the tarsals while other mammals, such as the xenarthrans, accomplish a similar end by means of different morphologies. However, a suite of features is identified that is shared by mammals capable of hind foot reversal. Hindlimb suspension effectively increases the potential feeding space available to a foraging mammal and represents a significant, and often unrecognized, alternative adaptive strategy to forelimb suspension and prehensile-tail suspension in primates. KEY WORDS positional behavior; feeding adaptations; skeletal morphology; prosimians; anthropoids; xenarthrans

Studies of primate positional behavior have only occasionally employed statistical testing because these data sets violate the assumptions underlying most standard statistical tests. As currently practiced, both common methods of collecting data on positional behavior involve sequential observations of a limited number of individuals, leading to data sets consisting of interdependent observations. Data collected from sequential observations may not be as dependent as currently accepted; however, approaches are available to deal with such data. Some previously applied tests are discussed, and an alternative strategy, a randomization test, is demonstrated. Randomization tests are based on observed rather than theoretical distributions. Thus, they are robust when applied to data sets which do not adhere to the strict assumptions inherent in standard tests. Randomization procedures suggested by Manly ((1991) Randomization and Monte Carlo Methods in Biology (New York: Chapman and Hall)) and Edgington ((1987) Randomization Tests (New York: Marcel Dekker, Inc.)) are applied to data collected for three species of lemurs studied at Ranomafana National Park, Madagascar (Lemur fulvus, Lemur rubriventer, and Lemur variegatus). Standard chi-square tests indicate statistically significant differences between these species in nearly all aspects of locomotor, postural, and substrate use behavior. In contrast, the randomization tests showed a significant difference only in the postures used by these lemurs. Lemur variegatus uses hindlimb suspensory postures much more often than L. fulvus or L. rubriventer, and the latter species use vertical clinging more often than L. variegatus. The results from the randomization tests are considered more reliable because by using individuals rather than observations as the units compared, they limit the problem of interdependence of observations and thus provide a conservative test. The particular randomization tests used also explicitly test the proposition that individuals of a species are more similar to each other than to individuals of other species. The lack of significant results is not surprising in light of the small number of individuals studied and the great deal of variability within a species for most of the variables considered.

More than one hundred undescribed foot elements of Cantius and other closely related notharctine adapids (7 species in all) from throughout the early Eocene (Wasatchian) Willwood Formation of the Bighorn Basin, Wyoming, have been analyzed. For four species (Cantius ralstoni, 'Copelemur' feretutus, Cantius frugivorus, and ?Pelycodus jarrovii) these represent the first described postcranial material. The clade of Cantius and allied genera in the Bighorn Basin includes several speciation events and both increases and decreases in body size. The largest species represented by tarsal remains (?Pelycodus jarrovii) is several times larger than the smallest, Cantius ralstoni. However, despite the number of species, temporal duration, and range of body size represented, there are no obvious changes in foot morphology as measured by various indices or by observation of qualitative features. This contrasts with the more obvious changes in dental features (e.g., development of hypocone and mesostyle) in the same group of species described by earlier authors. The fossil record of Cantius thus illustrates different kinds of evolutionary change in the dentition and tarsus. The dentition changes in both size and shape while the tarsus changes only in size. We describe significant differences in foot anatomy which distinguish notharctines from extant strepsirhines, including the nature of the articulations between the navicular and cuboid and the distal tarsus with the metatarsus. These features indicate that the fossil taxa are not particularly closely allied phylogenetically to either extant strepsirhines in general or lemurids in particular.

ABSTRACT Teilhardina belgica is one of the earliest fossil primates ever recovered and the oldest fossil primate from Europe. As such, this taxon has often been hypothesized as a basal tarsiiform on the basis of its primitive dental formula with four premolars and a simplified molar cusp pattern. Until recently [see Rose et al.: Am J Phys Anthropol 146 (2011) 281-305; Gebo et al.: J Hum Evol 63 (2012) 205-218], little was known concerning its postcranial anatomy with the exception of its well-known tarsals. In this article, we describe additional postcranial elements for T. belgica and compare these with other tarsiiforms and with primitive adapiforms. The forelimb of T. belgica indicates an arboreal primate with prominent forearm musculature, good elbow rotational mobility, and a horizontal, rather than a vertical body posture. The lateral hand positions imply grasps adaptive for relatively large diameter supports given its small body size. The hand is long with very long fingers, especially the middle phalanges. The hindlimb indicates foot inversion capabilities, frequent leaping, arboreal quadrupedalism, climbing, and grasping. The long and well-muscled hallux can be coupled with long lateral phalanges to reconstruct a foot with long grasping digits. Our phyletic analysis indicates that we can identify several postcranial characteristics shared in common for stem primates as well as note several derived postcranial characters for Tarsiiformes. Am J Phys Anthropol 156:388-406, 2015. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]