Intrinsic hand proportions of euarchontans and other mammals: implications for the locomotor behavior of plesiadapiforms

Arboreal primates have distinctive intrinsic hand proportions compared with many other mammals. Within Euarchonta, platyrrhines and strepsirrhines have longer manual proximal phalanges relative to metacarpal length than colugos and terrestrial tree shrews. This trait is part of a complex of features allowing primates to grasp small-diameter arboreal substrates. In addition to many living and Eocene primates, relative elongation of proximal manual phalanges is also present in most plesiadapiforms. In order to evaluate the functional and evolutionary implications of manual similarities between crown primates and plesiadapiforms, we measured the lengths of the metacarpal, proximal phalanx, and intermediate phalanx of manual ray III for 132 extant mammal species (n=702 individuals). These data were compared with measurements of hands in six plesiadapiform species using ternary diagrams and phalangeal indices. Our analyses reveal that many arboreal mammals (including some tree shrews, rodents, marsupials, and carnivorans) have manual ray III proportions similar to those of various arboreal primates. By contrast, terrestrial tree shrews have hand proportions most similar to those of other terrestrial mammals, and colugos are highly derived in having relatively long intermediate phalanges. Phalangeal indices of arboreal species are significantly greater than those of the terrestrial species in our sample, reflecting the utility of having relatively long digits in an arboreal context. Although mammals known to be capable of prehensile grips demonstrate long digits relative to palm length, this feature is not uniquely associated with manual prehension and should be interpreted with caution in fossil taxa. Among plesiadapiforms, Carpolestes, Nannodectes, Ignacius, and Dryomomys have manual ray III proportions that are unlike those of most terrestrial species and most similar to those of various arboreal species of primates, tree shrews, and rodents. Within Euarchonta, Ignacius and Carpolestes have intrinsic hand proportions most comparable to those of living arboreal primates, while Nannodectes is very similar to the arboreal tree shrew Tupaia minor. These results provide additional evidence that plesiadapiforms were arboreal and support the hypothesis that Euarchonta originated in an arboreal milieu.     

Preliminary analysis of<Emphasis Type="Italic"> Nacholapithecus</Emphasis> scapula and clavicle from Nachola,Kenya

The Miocene ape Nacholapithecus is known from rather complete skeletons; some of them preserve the shoulder joint, identified by three scapulae and one clavicle. Comparisons made with other Miocene and living apes (Proconsul, Equatorius, Ugandapithecus) suggest that the mobility of the scapulohumeral joint was important, and scapular features such as the morphology and position of the spine and the morphology of the acromion and axillary border resemble those of climbing arboreal primates except for chimpanzees, gorillas, or orang-utans. From the size of the scapula (male Nasalis size), it is clear that the animal is smaller than an adult chimpanzee, but the clavicle is almost as relatively long as those of chimpanzees. Some features closer to colobine morphology reinforce the hypothesis that Nacholapithecus was probably a good climber and was definitely adapted for an arboreal life.     

An oreopithecid proximal humerus from the middle miocene of Maboko Island,Kenya

A proximal humerus, recently recovered from the middle Miocene of Maboko Island, Kenya, provides the earliest evidence of postcranial structure and adaptation of Oreopithecidae. Provisionally attributed toNyanzapithecus pickfordi (Harrison, 1986), the specimen manifests a globose head, subequally large tuberosities, and a board, shallow bicipital groove. Although readily distinguished from the fundamentally cercopithecoid proximal humeral morphology ofVictoriapithecus (Senut, 1986), the Maboko Island oreopithecid, shows none of the derived features that are characteristic of the proximal humeri of extant hominoids. It is inferred from proximal humeral anatomy that the Maboko Island oreopithecid was an active arboreal scansor with moderate mobility at the shoulder but lacking adaptations for circumduction of the arm. In combination with craniodental evidence, proximal humeral morphology indicates that Oreopithecidae was a clade of hominoids which originated before the last common ancestor of extant apes and went extinct, without issue, in the later Miocene.     

New primate carpal bones from Rudabánya (late Miocene, Hungary): taxonomic and functional implications

We describe a scaphoid and two capitates from the late Miocene site of Rudabánya, Hungary using qualitative and quantitative comparisons to a large sample of hominoid, cercopithecoid, and platyrrhine primates. The scaphoid (RUD 202) is not fused to the os centrale and in this way is like most primates other than African apes and humans (hominines). Qualitatively, its morphology is most similar to Pongo, and univariate analyses generally confirm an ape-like morphology with an increased range of mobility. One capitate (RUD 167) is compatible in size to the scaphoid, and its morphology suggests a combination of monkey-like generalized arboreality and ape-like enhanced mobility. RUD 203 is a smaller, fragmentary capitate, about half the size of RUD 167, and preserves only the distal portion of the body with the third metacarpal articular surface. Its morphology is virtually identical to that of RUD 167, and an exact randomization test revealed that it is statistically likely to find two carpal bones of such disparate sizes within one taxon. However, due to morphological similarities with other Miocene hominoids as well as implications for size variation within one taxon and sex, we consider the taxonomic affiliation of RUD 203 to be unresolved. We attribute the scaphoid and RUD 167 capitate to the hominine Rudapithecus hungaricus (formerly Dryopithecus brancoi; see Begun et al., 2008) based on overall morphological similarity to extant apes, particularly Pongo, and not to the pliopithecoid Anapithecus hernyaki, the only other primate known from Rudabánya. The similarities in carpal morphology to suspensory taxa are consistent with previous interpretations of Rudapithecus positional behavior. The scaphoid and the RUD 167 capitate are consistent in size with a partial skeleton including associated postcranial and craniodental specimens from the same level at the locality and may be from the same individual. These are the first carpal bones described from Rudabánya and from this taxon, and they add to our understanding of the evolution of arboreal locomotion in late Miocene apes.     

Hominoid phalanges from the middle Miocene site of Paşalar, Turkey

Eleven proximal and ten intermediate partial or complete hominoid phalanges have been recovered from the middle Miocene site of Pa?alar in Turkey. Based on species representation at Pa?alar, it is likely that most or all of the phalanges belong to Griphopithecus alpani rather than Kenyapithecus kizili, but both species may be represented. All of the complete or nearly complete phalanges appear to be manual, so comparisons to extant and other fossil primate species were limited to manual phalanges. Comparisons were made to extant hominoid and cercopithecoid primate genera expressing a variety of positional repertoires and varying degrees of arboreality and terrestriality. The comparisons consisted of a series of bivariate indices derived from previous publications on Miocene catarrhine phalangeal morphology. The proximal phalanges have dorsally expanded proximal articular surfaces, which is characteristic of cercopithecoids and most other Miocene hominoids, and indicates that the predominant positional behaviors involved pronograde quadrupedalism. Among the extant primates, many of the proximal and intermediate phalangeal indices clearly distinguish more habitually terrestrial taxa from those that are predominantly arboreal, and especially from taxa that commonly engage in suspensory activities. For nearly every index, the values of the Pa?alar phalanges occupy an intermediate position-most similar to values for Pan and, to a lesser extent, Macaca-indicating a generalized morphology and probably the use of both arboreal and terrestrial substrates. At least some terrestrial activity is also compatible with reconstructions of the Pa?alar habitat. Most proximal and intermediate phalanges of other middle and late Miocene hominoids have similar index values to those of the Pa?alar specimens, revealing broadly similar manual phalangeal morphology among many Miocene hominoids.     

Partial skeleton of Proconsul nyanzae from Mfangano Island,Kenya

A partial skeleton attributed to Proconsul nyanzae (KNM-MW 13142) is described. The fossils were found at a site on Mfangano Island, Kenya, which dates to 17.9 ± .1 million years ago. KNM-MW 13142 consists of six partial vertebrae (T12-S1), a nearly complete hipbone, most of the right femur and left femoral shaft, a fragmentary tibia and fibula, and a nearly complete talus and calcaneus. This skeleton provides the first pelvic fossil known for any East African Miocene hominoid. The new Proconsul specimen is compared to a large sample of extant anthropoids to determine its functional and phylogenetic affinities. In most aspects of its anatomy, KNM-MW 13142 closely resembles nonhominoid anthropoids. This individual had a long, flexible spine, narrow torso, and habitually pronograde posture, features characteristic of most extant monkeys. Evidence of spinal musculature suggests a generalized condition intermediate between that of cercopithecoids and hylobatids. The hindlimb of KNM-MW 13142 exhibits relatively mobile hip and ankle joints, with structural properties of the femur like those of hominoids. This mix of features implies a pattern of posture and locomotion that is unlike that of any extant primate. Many aspects of the Proconsul nyanzae locomotor skeleton may represent the primitive catarrhine condition. © 1993 Wiley-Liss, Inc.     

The form of the talus in some higher primates: a multivariate study

Sixteen measurements of the talus have been taken on 334 tali of a total of eleven primate groups and several additional single individual specimens. Multivariate morphometric (canonical and generalized distance) analyses of these data in extant higher primates are presented and used to define the relative morphological positions of fossils of the genera Proconsul and Limnopithecus, of individual specimens from Kromdraai, Olduvai and Kiik-Koba (Homo neanderthalensis), and a group of specimens of Bronze Age man from Jericho. Following preliminary studies the ultimate analysis suggests that the various extant arboreal primates examined fall within an envelope that is defined by Macaca together with various other Old World monkeys and extending in different directions to the extreme genera (a) Pongo, (b) Hylobates and (c) Ateles. This separation is thus one which defines generally quadrupedal monkeys and separates the various extreme arboreal locomotor modes of (a) acrobatic climbing and hanging, (b) richochetal brachiation and (c) prehensile-tailed arm-swinging and hanging, respectively. Man and the African apes are well separated both from each other and from this spectrum of arboreally adapted genera. Bronze Age man from Jericho and Neandertal man from Kiik-Koba lie relatively close to the position for modern man although significantly separated from him. Limnopithecus, Proconsul, and the specimens from Kromdraai and Olduvai all lie within the envelope of arboreal species and specifically rather close to, although significantly different from, the orang-utan; they differ markedly from both man and the African apes. The possibility exists that the resemblances of Proconsul and Limnopithecus relate to arboreal habitus in these species. The findings for the specimens from Kromdraai and Olduvai suggest either that the morphological resemblances to arboreal forms relate to a previous arboreal history for these species, or that bipedality is much less advanced or uniquely different from that displayed by Homo. It is not inconceivable that both conditions might apply.     

Functional morphology of cercopithecoid primate metacarpals

The primate fossil record suggests that terrestriality was more common in the past than it is today, particularly among cercopithecoid primates. Whether or not a fossil primate habitually preferred terrestrial substrates has typically been inferred from its forelimb anatomy. Because extant large-bodied terrestrial cercopithecine monkeys utilize digitigrade hand postures during locomotion, being able to identify if a fossil primate habitually adopted digitigrade postures would be particularly revealing of terrestriality in this group. This paper examines the functional morphology of metacarpals in order to identify osteological correlates of digitigrade versus palmigrade hand postures. Linear measurements were obtained from 324 individuals belonging to digitigrade and palmigrade cercopithecoid species and comparisons were made between hand posture groups. Digitigrade taxa have shorter metacarpals, relative to both body mass and humerus length, than palmigrade taxa. Also, digitigrade taxa tend to have metacarpals with smaller dorsoventral diameters, relative to the product of body mass and metacarpal length, compared to palmigrade taxa. The size and shape of the metacarpal heads do not significantly differ between hand posture groups. Multivariate analyses suggest that metacarpal shape can only weakly discriminate between hand posture groups. In general, while there are some morphological differences in the metacarpals between hand posture groups, similarities also exist that are likely related to the fact that even digitigrade cercopithecoids can adopt palmigrade hand postures in different situations (e.g., terrestrial running, arboreal locomotion), and/or that the functional demands of different hand postures are not reflected in all aspects of metacarpal morphology. Therefore, the lack of identifiable adaptations for specific hand postures in extant cercopithecoids makes it difficult to determine a preference for specific habitats from fossil primate hand bones.     

Evolution of femur and tibia in higher primates: Adaptive morphological patterns and phylogenetic diversity

Seventy six metrical traits measured on the femur and tibia of three higher primate groups —Ceboidea, Cercopithecoidea, Hominoidea have been processed by various univariate and multivariate statistical methods to survey the process of evolution of the morphology of the femur and tibia in higher primates. Intragroup and intergroup variability, similarity and differences as well as various aspects of scaling and sexual dimorphism have been analyzed to study adaptive trends and phylogenetic diversity in higher primates, in individual superfamilies and to explore the adaptive morphological pattern of early hominids and basic differences between hominids and pongids. Two basic morphotypes of the femur and tibia in higher primates have been determined. They are (1) advanced hominoid morphotype (hominids and pongids) and (2) ancestral higher primate morphotype (platyrrhine and cattarrhine monkeys, early hominoids, and hylobatids). Cebid lower limb bones are adapted to arboreal quadrupedalism with antipronograde features while femur and tibia of cercopithecid monkeys are basically adapted to the semi-arboreal locomotion. Early hominoids (Proconsul) and hylobatids are morphologically different from pongids; some features are close toAteles or other monkey species. Pongids and hominids are taken as one major morphological group with different scaling and some functional and morphological similarities. Numerous analogous features were described on the lower limb skeleton ofPan andPongo showing analogous ecological parameters in their evolution. Major morphological and biomechanical trends are analyzed. It is argued that early advanced hominoid morphology is ancestral both to the pongids and to early hominids. The progressive morphological trend in early hominids has been found fromA. afarensis with ancestral hominid morphology, toH. habilis with an elongated femur and structural features similar to advanced hominids. A detailed phylogenetic analysis of higher primate femur and tibia is also presented.     

First hominoid from the Miocene of Ethiopia and the evolution of the catarrhine elbow

The first known fossil ape from the early-middle Miocene of Fejej, Ethiopia, is described here. The specimen, FJ-18SB-68, is a partial ulna from a locality dated by ⁴⁰Ar/³⁹Ar and paleomagnetic methods to a minimum age of 16.18 MYA. Compared to a variety of extant and fossil ulnae, FJ-18SB-68 is most similar to Turkanapithecus, Proconsul, and Pliopithecus, and appears to have been an arboreal quadruped with substantial forearm rotational mobility. Among the extant ulnae, canonical variates analysis successfully discriminates platyrrhines from catarrhines and within the latter, cercopithecoids from hominoids. Basal catarrhines (e.g., Aegyptopithecus) are platyrrhine-like in their morphology. Two basic trends appear to evolve from this generalized template: one with less mobile and more habitually pronated forearms, as seen in living and fossil cercopithecoids (including Victoriapithecus and Paracolobus), and another with greater forearm rotational mobility in fossil and modern hominoids. Primitive Miocene apes, including Proconsul, Turkanapithecus, and FJ-18SB-68, share with extant hominoids a more laterally positioned and laterally facing radial notch and an incipient trochlear keel. This morphology, along with a large insertion area for m. brachialis, suggests a departure from the more habitually pronated hand posture of monkeys and may indicate greater climbing abilities in these arboreally quadrupedal apes. Later Miocene apes, such as Oreopithecus and Dryopithecus share additional morphological features with hominoids, indicating considerable suspensory and climbing capabilities. Am J Phys Anthropol 105:257–277, 1998. © 1998 Wiley-Liss, Inc.     

Subchondral Bone Apparent Density and Locomotor Behavior in Extant Primates and Subfossil Lemurs <Emphasis Type="Italic">Hadropithecus</Emphasis> and <Emphasis Type="Italic">Pachylemur</Emphasis>

We analyze patterns of subchondral bone apparent density in the distal femur of extant primates to reconstruct differences in knee posture, discriminate among extant species with different locomotor preferences, and investigate the knee postures used by subfossil lemur species Hadropithecus stenognathus and Pachylemur insignis. We obtained computed tomographic scans for 164 femora belonging to 39 primate species. We grouped species by locomotor preference into knuckle-walking, arboreal quadruped, terrestrial quadruped, quadrupedal leaper, suspensory and vertical clinging, and leaping categories. We reconstructed knee posture using an experimentally validated procedure of determining the anterior extent of the region of maximal subchondral bone apparent density on a median slice through the medial femoral condyle. We compared subchondral apparent density magnitudes between subfossil and extant specimens to ensure that fossils did not display substantial mineralization or degradation. Subfossil and extant specimens were found to have similar magnitudes of subchondral apparent density, thereby permitting comparisons of the density patterns. We observed significant differences in the position of maximum subchondral apparent density between leaping and nonleaping extant primates, with leaping primates appearing to use much more flexed knee postures than nonleaping species. The anterior placement of the regions of maximum subchondral bone apparent density in the subfossil specimens of Hadropithecus and Pachylemur suggests that both species differed from leaping primates and included in their broad range of knee postures rather extended postures. For Hadropithecus, this result is consistent with other evidence for terrestrial locomotion. Pachylemur, reconstructed on the basis of other evidence as a committed arboreal quadruped, likely employed extended knee postures in other activities such as hindlimb suspension, in addition to occasional terrestrial locomotion.     

Not so fast: Speed effects on forelimb kinematics in cercopithecine monkeys and implications for digitigrade postures in primates

Terrestrial mammals are characterized by their digitigrade limb postures, which are proposed to increase effective limb length (ELL) to achieve preferred or higher locomotor speeds more efficiently. Accordingly, digitigrade postures are associated with cursorial locomotion. Unlike most medium‐ to large‐sized terrestrial mammals, terrestrial cercopithecine monkeys lack most cursorial adaptations, but still adopt digitigrade hand postures. This study investigates when and why terrestrial cercopithecine monkeys adopt digitigrade hand postures during quadrupedal locomotion. Three cercopithecine species (Papio anubis, Macaca mulatta, Erythrocebus patas) were videotaped moving unrestrained along a horizontal runway at a range of speeds (0.4–3.4 m/s). Three‐dimensional forelimb kinematic data were recorded during forelimb support. Hand posture was measured as the angle between the metacarpal segments and the ground (MGA). As predicted, a larger MGA was correlated with a longer ELL. At slower speeds, subjects used digitigrade postures (larger MGA), however, contrary to expectations, all subjects used more palmigrade hand postures (smaller MGA) at faster speeds. Digitigrade postures at slower speeds may lower cost of transport by increasing ELL and step lengths. At higher speeds, palmigrade postures may be better suited to spread out high ground reaction forces across a larger portion of the hand thereby potentially decreasing stresses in hand bones. It is concluded that a digitigrade forelimb posture in primates is not an adaptation for high speed locomotion. Accordingly, digitigrady may have evolved for different reasons in primates compared to other mammalian lineages. Am J Phys Anthropol 2009. © 2009 Wiley‐Liss, Inc.     

A new hominoid hamate and first metacarpal from the Late Miocene Nagri Formation of Pakistan

A hamate and the proximal part of a first metacarpal from the type locality of the Nagri Formation in Pakistan, and attributed to Sivapithecus parvada, are described. In overall proportions, the hamate is rather robust, showing most similarity to that of Gorilla. Unlike extant hominoids it lacks a well-developed hamulus, and its triquetral facet is morphologically dissimilar to that in extant anthropoids. The morphology of the hamate indicates effective weight transmission through the ulnar side of the wrist, limited ulnar deviation and restricted extension in the triquetrohamate joint, and stability of the hamatometacarpal joints. The morphology of the partial first metacarpal is most similar to that of Pan. Previously described postcranial bones of S. parvada indicate that its locomotor behaviour included both quadrupedalism and climbing. This is consistent with the limited evidence of the first metacarpal, whereas the hamate strongly emphasizes the quadrupedal aspect of the locomotor repertoire.     

The lorisiform wrist joint and the evolution of "brachiating" adaptations in the hominoidea.

In lorisines (Loris, Nycticebus, Perodicticus, Arctocebus), the tip of the ulna is reduced to the dimensions of a styloid process, a new and more proximal ulnar head is developed, and the pisiform is displaced distally away from its primitive contact with the ulna. In some Nycticebus, intra-articular tissues separate the ulna from the triquetrum. These traits are not seen in other quadrupedal primates, but they are characteristic of extant hominoids. Among hominoids, these features have been interpreted as adaptations to arm-swinging locomotion. Since hominoid-like features of the wrist joint are found in lorisines, but not in New World monkeys that practice arm-swinging locomotion, these features may have been evolved in both lorisines and large hominoids to enhance wrist mobility for cautious arboreal locomotion involving little or no leaping. Most of the other morphological traits characteristic of modern hominoids can be explained as adaptations to cautious quadrupedalism as well as to brachiation, and may have developed for different reasons in different lineages descended from an unspecialized cautious quadruped resembling Alouatta.     

New proconsuloid postcranials from the early Miocene of Kenya

New early Miocene forelimb fossils have been recovered from the Songhor and Lower Kapurtay localities in southwestern Kenya. We describe four specimens that are similar in size and functional capabilities. Their specific allocation is problematic but these forelimb specimens must belong to either Rangwapithecus gordoni or Proconsul africanus. If these new postcranial specimens should belong to R. gordoni, on the basis of size and common dental specimens found at Songhor, they represent a new elbow complex. The morphology of these fossils is anatomically and functionally similar to that of Proconsul. The proconsuloid elbow complex allows extensive forelimb rotations and is capable of performing arboreal quadrupedalism and climbing activities. No suspensory adaptations are apparent. The proconsuloid elbow complex remains a good ancestral condition for hominoid primates.     

Trabecular Architecture of the Manual Elements Reflects Locomotor Patterns in Primates

The morphology of trabecular bone has proven sensitive to loading patterns in the long bones and metacarpal heads of primates. It is expected that we should also see differences in the manual digits of primates that practice different methods of locomotion. Primate proximal and middle phalanges are load-bearing elements that are held in different postures and experience different mechanical strains during suspension, quadrupedalism, and knuckle walking. Micro CT scans of the middle phalanx, proximal phalanx and the metacarpal head of the third ray were used to examine the pattern of trabecular orientation in Pan, Gorilla, Pongo, Hylobates and Macaca. Several zones, i.e., the proximal ends of both phalanges and the metacarpal heads, were capable of distinguishing between knuckle-walking, quadrupedal, and suspensory primates. Orientation and shape seem to be the primary distinguishing factors but differences in bone volume, isotropy index, and degree of anisotropy were seen across included taxa. Suspensory primates show primarily proximodistal alignment in all zones, and quadrupeds more palmar-dorsal orientation in several zones. Knuckle walkers are characterized by having proximodistal alignment in the proximal ends of the phalanges and a palmar-dorsal alignment in the distal ends and metacarpal heads. These structural differences may be used to infer locmotor propensities of extinct primate taxa.     

New hand bones of Hadropithecus stenognathus: implications for the paleobiology of the Archaeolemuridae

A partial, associated skeleton of Hadropithecus stenognathus (AHA-I) was discovered in 2003 at Andrahomana Cave in southeastern Madagascar. Among the postcranial elements found were the first hand bones (right scaphoid, right hamate, left first metacarpal, and right and left fifth metacarpals) attributed to this rare subfossil lemur. These hand bones were compared to those of extant strepsirrhines and catarrhines in order to infer the positional adaptations of Hadropithecus, and they were compared to those of Archaeolemur in order to assess variation in hand morphology among archaeolemurids. The scaphoid tubercle does not project palmarly as in suspensory and climbing taxa, and the hamate has no hook at all (just a small tubercle), which also points to a poorly developed carpal tunnel. There is a distinctive, radioulnarly directed "spiral" facet for articulation with the triquetrum that is most similar in orientation to that of more terrestrial primates (i.e., Lemur catta, Papio, and Gorilla). The first metacarpal is very reduced and represents only 48% of the length of metacarpal V, as in Archaeolemur, which suggests that pollical grasping of arboreal supports was not important. Compared to Archaeolemur, the shaft of metacarpal V is gracile, and the head has no dorsal ridge and lacks characteristics functionally associated with digitigrade, extended metacarpophalangeal joint postures. Proximally, the articular facet for the hamate is oriented more dorsally. Thus, the carpometacarpal joint V appears to have a distinctive hyperextended set, which has no analog among living or extinct primates. The carpals of Hadropithecus are diagnostic of a pronograde, arboreal and terrestrial (although not digitigrade) locomotor repertoire that typifies Lemur catta and some Old World monkeys. No clinging, suspensory, or climbing specializations that characterize indriids or lorises can be found in the hand of this subfossil lemur. The hand of Hadropithecus likely had similar ranges of movement at the radiocarpal and midcarpal joints as of those of pronograde primates, such as lemurids, for which the hand is held in a more extended, pronated, and neutral (i.e., showing less ulnar deviation) position during locomotion in comparison to that of vertical clingers or slow climbers. Although highly autapomorphic, the hand of Hadropithecus resembles that of its sister taxon, Archaeolemur, in having a very reduced pollex and an articular facet on the scaphoid for a sizeable prepollex. These unusual hand features reinforce the monophyly of the Archaeolemuridae.     

Biometrical characteristics of primate hands

The lenght proportions of the primate hands and their elements are analyzed in 43 extant genera and 6 fossil genera. The length of the hand in relation to the forelimb length does not characterize taxonomic groups, but rather locomotor modes, such as vertical-clinging-and-leaping, claw-climbing, and terrestrial quadrupedalism, as opposed to arboreal quadrupedalism. The relative lengths of the carpus, metacarpus, and digits appear mainly related to the phylogenetic history of the primates. Paraxony, instead of mesaxony, is the most frequent pattern of the simiiform hand, whereas hypermesaxony characterizes humans, hylobatids, and tarsiers. The proportions of the primitive euprimate hand are discussed in the light of the hand proportions of extant primates. Proportions drawn from hand remains ofMegaladapis edwardsi, Proconsul africanus, Mesopithecus pentelici, Notharctus, Adapis parisiensis, andPlesiadapis insignis are compared to those of extant primates, and discussed from both phylogenetical and functional points of view. To the memory of our colleague Jacques Lessertisseur.     

Morphometric affinities of the human shoulder

To analyze differences between apes and monkeys and the affinities of man, we have studied the shoulder girdle of 327 specimens of anthropoid primates. The scapula, clavicle and humerus are viewed as an integrated functional complex on the basis of 18 measurements. Several varieties of multivariate analysis show that man is clearly closer to other hominoids than to the included monkey taxa (whether terrestrial or arboreal, Old World or New World). The marked shoulder differences between apes and monkeys and similarities between apes and man correlate with the muscular anatomy, which in hominoids allows the motions involved in their locomotion and feeding behavior. As the hominid-pongid correspondence in shoulder morphology is especially detailed regarding the functionally important joint surfaces, it is consistent with a fairly recent period of common ancestry and behavior. No hypothetical evolutionary pathway or ancestral form of the human shoulder need look far beyond the model afforded by extant pongids. In contrast with previous studies on the primate shoulder, these results agree with information accumulating from other systems—comparative anatomy, primate behavior, and molecular biology — in suggesting very close relationship between man and extant African pongids.