Functional anatomy of the hand of Australopithecus africanus

The Sterkfontein hand bones, attributed to Australopithecus africanus, were analysed to determine potential hand function of the power grip type of this species. The metacarpus is as stable as that of modern humans, as indicated by the depth of the groove on the base of metacarpal 2, the styloid process of metacarpal 3, the base articular surface areas, and the ligament markings on the bases of the metacarpals. The flexion and rotation of metacarpal 5 might have been less than that of modern humans, due to a more marked ventral articular lip on the base. The metacarpus acts as a lever, acting in various planes. The extensor carpi ulnaris and extensor carpi radialis longus muscles were probably better developed than in modern humans. The extensor carpi radialis brevis and flexor carpi radialis muscles would probably have been as well developed as in modern humans. None of the long tendons have a mechanical disadvantage as compared to modern humans. The metacarpals have a high robusticity index. The proximal phalanges show some midshaft swelling, slightly greater curvature than in modern humans, and some side to side bowing: pongid features. The fibrous flexor sheath markings are well developed, but resemble those of modern humans rather than those of the pongids. A single middle phalanx resembles that of modern humans, and has well developed ridges for insertion of the flexor digitorum superficialis muscle. The distal phalanx of the thumb has a well developed region for insertion of the flexor pollicis longus muscle, and has a mechanical advantage over modern humans for action of this muscle at the interphalangeal joint. The features indicate that the hand of A. africanus was well adapted to powerful hand use, as in hammering, striking, chopping, scraping, and gouging actions, as well as for throwing and climbing activities.     

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.     

Comparative assessment of the ischial morphology of Victoriapithecus macinnesi

An almost complete primate ischium was recovered from middle Miocene (ca. 15 ma) deposits of Maboko Island (Kenya) in 1987. The specimen shows numerous similarities to the ischial morphology of extant cercopithecids and is attributed to Victoriapithecus macinnesi (Von Koenigswald, 1969), the early Old World monkey best known from Maboko Island. The Victoriapithecus ischium provides the first evidence of early Old World monkey pelvic girdle anatomy. The ischium is characterized by an obliquely oriented and broadly flaring tuberosity, a relatively small acetabulum with little ventrally directed curvature of its caudal portion, a long ischial body and a flange-like ischial spine positioned caudal to the rim of the acetabulum. In these features, Victoriapithecus most closely resembles the vervet monkey, Cercopithecus aethiops. The fossil specimen indicates that Victoriapithecus possessed ischial callosities, a mobile tail and adaptations for (possibly cursorial) quadrupedalism with an adducted posture of the thigh. The occurrence of ischial callosities in Victoriapithecus extends the documented antiquity of this feature in catarrhines by more than 12 million years and shows that the distinctive “sitting-sleeping” adaptations of Old World monkeys (Washburn, 1957) originated prior to the divergence of Colobinae and Cercopithecinae. Differences of developmental sequence and tissue composition indicate that the ischial pads of cercopithecids, hylobatids, and pongids may have arisen independently, through parallel evolution. Contrary to Strasser and Delson (1987), discontinuity of ischial callosities was probably the primitive condition for male cercopithecids.     

Look in the trees: Hylobatids as evolutionary models for extinct hominins

Studying extant apes is of central importance to paleoanthropology. This approach is informative in inferring how hominin skeletal morphology reflects phylogeny, behavior, development, and ecological context. Traditionally, great apes have dominated the paleoanthropological literature as extant analogs for extinct hominins, to the exclusion of their phylogenetic sister group, the hylobatids. Phylogenetic proximity, large body size, and high encephalization quotients may have contributed to decisions to use great apes as models for hominins. However, if we reexamine hylobatids as extant models for extinct hominins—using modern phylogenetic, behavioral, and ecological data—this clade is uniquely poised to inform future frameworks in paleoanthropology. The following features make hylobatids strong analogs for extinct hominins: taxonomic diversity, the timing of diversification, hybridization between species, small body size, and reduced sexual dimorphism. Based on these shared features, hylobatids offer future opportunities to paleoanthropology, and provide a much richer extant analog than is currently recognized.     

The locomotion of Babakotia radofilai inferred from epiphyseal and diaphyseal morphology of the humerus and femur

Palaeopropithecids, or “sloth lemurs,” are a diverse clade of large‐bodied Malagasy subfossil primates characterized by their inferred suspensory positional behavior. The most recently discovered genus of the palaeopropithecids is Babakotia, and it has been described as more arboreal than Mesopropithecus, but less than Palaeopropithecus. In this article, the within‐bone and between‐bones articular and cross‐sectional diaphyseal proportions of the humerus and femur of Babakotia were compared to extant lemurs, Mesopropithecus and Palaeopropithecus in order to further understand its arboreal adaptations. Additionally, a sample of apes and sloths (Choloepus and Bradypus) are included as functional outgroups composed of suspensory adapted primates and non‐primates. Results show that Babakotia and Mesopropithecus both have high humeral/femoral shaft strength proportions, similar to extant great apes and sloths and indicative of forelimb suspensory behavior, with Babakotia more extreme in this regard. All three subfossil taxa have relatively large femoral heads, also associated with suspension in modern taxa. However, Babakotia and Mesopropithecus (but not Palaeopropithecus) have relatively small femoral head surface area to shaft strength proportions suggesting that hind‐limb positioning in these taxa during climbing and other behaviors was different than in extant great apes, involving less mobility. Knee and humeral articular dimensions relative to shaft strengths are small in Babakotia and Mesopropithecus, similar to those found in modern sloths and divergent from those in extant great apes and lemurs, suggesting more sloth‐like use of these joints during locomotion. Mesopropithecus and Babakotia are more similar to Choloepus in humerofemoral head and length proportions while Palaeopropithecus is more similar to Bradypus. These results provide further evidence of the suspensory adaptations of Babakotia and further highlight similarities to both extant suspensory primates and non‐primate slow arboreal climbers and hangers. J. Morphol. 277:1199–1218, 2016. © 2016 Wiley Periodicals, Inc.     

Mandibular shape variation in mainland and insular hylobatids

Although hylobatids are the most speciose of the living apes, their morphological interspecies and intraspecies variation remains poorly understood. Here, we assess mandibular shape variation in two species of Hylobates, white-handed (Hylobates lar) and black-handed (Hylobates agilis) gibbons. Using 71 three-dimensional landmarks to quantify mandibular shape, interspecies and intraspecies variation and geographic patterns of mandibular shape are examined in a mixed sex sample of adult H. lar and H. agilis through generalized Procrustes analysis, Procrustes analysis of variance, and principal components analysis. We find that relative to H. agilis, H. lar exhibits a higher amount of variation in mandibular shape. Both species demonstrate similar allometric patterns in mandibular shape. We also highlight a geographic pattern in mandibular shape variation. Compared to mainland hylobatids, insular hylobatids have relatively lower, more posteriorly oriented, and anteroposteriorly wider mandibular condyles, with an increased distance between the condyles and the coronoid processes. This geographic pattern could reflect differences in functional demands on the mandible during mastication and/or could be driven by factors often associated with evolutionary pressures of island populations relative to mainland populations. The findings of this study highlight how little is known about Hylobates morphological variation and how important this is for using Hylobates to help interpret the primate fossil record. Understanding interspecific and intraspecific variation in extant primates is vital to interpreting variation in the primate fossil record.     

禄丰粗壮池猿头骨的初步观察——兼论池猿的系统关系

本文通过粗壮池猿头骨新材料的初步观察得出,它与欧洲上猿的头骨比较接近,而在某些特征上又与现生长臂猿相似。这与牙齿和颌骨研究的结果是一致的。本文还对亚洲第三纪长臂猿类与其他同时代长臂猿类的关系作了初步的探讨,并对池猿的系统关系作了论述。     

Diverse oxyporine rove beetles from the Early Cretaceous of China (Coleoptera: Staphylinidae)

Two new genera and species, Protoxyporus grandis gen. et sp.n. and Cretoxyporus extraneus gen. et sp.n. , are described and figured on the basis of two well‐preserved impression fossils from the Lower Cretaceous Yixian Formation of China. The two genera display a combination of traits that are diagnostic of the extant staphylinid subfamily Oxyporinae: large and prominent mandibles, distinctly separated mesocoxae, abdominal tergites III–VII each with a pair of basolateral ridges, and abdominal intersegmental membranes with ‘brick‐wall’ pattern. Protoxyporus differs from extant Oxyporus in retaining the following plesiomorphic features: an elongate intercoxal process (or longitudinal carina) between metacoxae, relatively narrowly separated mesocoxae, less developed metaventral anterior process, and long infraorbital ridges. Cretoxyporus is morphologically very similar to Oxyporus, but retains distinct elongate infraorbital ridges. The discovery of two new oxyporine genera suggests that the early oxyporines were more diverse and their evolutionary history more complicated than previously documented. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:11503976‐D577‐45D2‐ACCB‐8226782EF817 .     

Functional and adaptive significance of primate pads and claws: Evidence from New World anthropoids

This study tests predicted morphoclines in fingertip morphology among four small-bodied (<1 kg) New World monkeys (Saimiri sciureus, Leontopithecus rosalia, Callithrix jacchus, and Saguinus oedipus) in order to test previous functional and adaptive explanations for the evolution of flattened nails, expanded apical pads, and grasping extremities within the Order Primates. Small-bodied platyrrhines which frequently forage among small-diameter substrates are expected to possess 1) relatively expanded apical pads, 2) well-developed epidermal ridges, 3) distally broad terminal phalanges, and 4) reduced flexor and extensor tubercles compared to those species which use large-diameter arboreal supports more frequently for their locomotor and postural behaviors. Results show that as the frequency of small-branch foraging increases among taxa within this sample, relative distal phalanx breadth also increases but distal phalanx length, height, and flexor tubercle size decrease. Moreover, epidermal ridge development becomes more pronounced as the frequency of small-branch foraging increases. Terminal phalanx breadth and epidermal ridge complexity are both positively correlated with apical pad size. The large, flexible apical pad increases stability of the hand and foot on small-diameter arboreal supports because the pad can contact the substrate in several planes which, in turn, enables the pad to resist disruptive forces from different directions by friction and interlocking (Hildebrand, 1995). The observed morphoclines demonstrate that a gradient in form from claw- to nail-like tegulae exists among these taxa. Thus, the distinction between claw- and nail-bearing platyrrhines is essentially arbitrary. These observations corroborate Cartmill's (1972) functional and adaptive model for the loss of claws in primates: namely, expanded apical pads are required for habitual locomotor and postural behaviors on small-diameter supports whereas claws are more useful for positional behaviors on large-diameter substrates. Finally, results from this study support previous suggestions that the keeled tegulae of callitrichines represent a derived postural adaptation rather than a primitive retention from an ancestral eutherian condition. Am J Phys Anthropol 106:113–127, 1998. © 1998 Wiley-Liss, Inc.     

Quantitative analyses of cross-sectional shape of the distal radius in three species of macaques

I conducted quantitative analyses of the cross-sectional shape of the distal radial shaft in three species of macaques, which differ in locomotor behavior: semi-terrestrial Japanese macaques (Macaca fuscata), arboreal long tailed macaques (M. fascicularis), and relatively terrestrial rhesus macaques (M. mulatta). I took CT scans of the distal radial shafts of a total of 180 specimens at the level of the inferior radio-ulnar articulation. From each CT image, the periosteal outline of the radius was traced automatically by a digital imaging technique. I determined five points (landmarks) on the outline by developing a standardized morphometric technique. Bone surface lengths were measured by using these landmarks and their soft tissue correlates were investigated. The results of this study were as follows: (1) Semi-terrestrial M. fuscata has features that are approximately intermediate between those of the other two species. M. fuscata has a relatively small groove for M. abductor pollicis longus and a large groove for Mm. extensor carpi radialis longus et brevis. These characters resemble those of M. fascicularis. On the other hand, the ulnar notch of M. fuscata is relatively large, a character which is similar to that of M. mulatta. Moreover, compared to the other two macaques, the surface of the flexor muscles of M. fuscata is intermediate in size. (2) The more terrestrial M. mulatta has a relatively large groove for M. abductor pollicis longus and a small groove for Mm. extensor carpi radialis longus et brevis. Moreover, M. mulatta has a relatively large ulnar notch and a small surface for the flexor muscles. (3) The arboreal M. fascicularis has similar features to those of M. fuscata for the first and second relative size index. However, in the ulnar notch, M. fascicularis has a peculiar character and the surface for the flexor muscles is relatively large compared to those of the other two species. These results can be interpreted in terms of positional habits and presumed functional demands. A form-functional study by Lemelin and Schmitt also corroborates the interpretations of the present study. Thus, the distal region of the forearm strongly reflects muscular development and joint resultant force, and is an important region for investigating locomotor adaptations in primates. The present study reveals the possibility of using this type of morphometric analysis for reconstructing the positional behavior of fossil primates.     

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.     

A new cajaro catfish (Siluriformes: Pimelodidae:Phractocephalus) from the Late Miocene of southwestern Amazonia and its relationship to °Phractocephalus nassi of the Urumaco Formation

A new fossil species of the living catfish genusPhractocephalus is described from fluvial Sediments of late Miocene age in Acre State, Brazil and the Madre de Dios region, Peru. †Phractocephalus acreornatus n. sp., is known from a complete neurocranium with associated Weberian complex vertebrae and posttemporal-supracleithra, and several isolated skeletal elements. °Phractocephalus acreornatus is diagnosed by the following combination of characters: 1) anterior half of supraoccipital, frontals and sometimes mesethmoid with coarse parallel ridges and sulci in addition to reticulating ridges and subcircular pits; 2) mesethmoid very broad and coarsely ornamented; 3) lateral ethmoid projecting anteriorly above palatine condyle into olfactory capsule, its anterolateral margin convex and fluted, and its orbital notch reduced; 4) supraoccipital process long, concealing Weberian vertebrae in dorsal view; 5) opercle covered with rough, reticulating ridges and pits; 6) interopercle relatively deep, its outer side coarsely ornamented; 7) pectoral spine shaft ornamented with reticulating ridges and pits. Variability of the form of the much expanded supraoccipital process inPhractocephalus is evaluated for its taxonomic significance. Although °P.acreornatus is distinct from both modernP. hemloliopterus and fossil °P. nassi, like most Miocene fossil fishes from South America, this extinct species is closely similar to its relatives. Available characters provide evidence for a close relationship between °P. acreornatus and °P. nassi from the Urumaco Formation, Venezuela. The provenance of these late Miocene catfishes in lowland western Amazonia and north-central South America is congruent with paleogeographic modeis positing a large, north flowing “Paleo-Amazon-Orinoco” river System in the Andean foreland basin during the Neogene.      

EQUISETUM CLARNOI,A NEW SPECIES BASED ON PETRIFACTIONS FROM THE EOCENE OF OREGON

Equisetum clarnoi is described from four silicified stem fragments and numerous small roots from the Eocene Clarno Chert of Jefferson County, Oregon. Stems are up to 8.0 mm in diam and have sunken stomata arranged vertically in a single line flanking each of the external biangulate stem ridges, features that clearly ally this species with the subgenus Hippochaete. External stem ridges are equal in number to the carinal hypodermal bands. The hypodermis is composed of fibers and has prominent carinal bands up to 0.75 mm long and shorter vallecular bands. Cortical parenchyma cells enclose prominent vallecular canals which are lined by specialized thick-walled parenchyma cells. The double, common endodermis has prominent casparian strips. Vascular bundles are composed of four to seven metaxylem tracheids flanking each side of the phloem and protoxylem tracheids which occur singly on the internal surface of the small carinal canals. Leaf sheaths in cross section have an adaxial fibrous layer and an external or near external fibrous bundle. Roots are up to 2.0 mm in diam and have paired cuboidal epidermal cells from which root hairs arise. The stele of the root is central and shows exarch primary xylem maturation. Equisetum clarnoi most closely resembles the extant Equisetum hyemale var. affine.     

New Sivapithecus postcranial specimens from the Siwaliks of Pakistan

Several new postcranial elements of Sivapithecus from the Siwaliks of Pakistan are described. These include a distal femur from the U-level of the Dhok Pathan Formation, a navicular from the Chinji Formation, and seven manual and pedal phalanges from the Nagri Formation. The functional morphology of these elements adds new detail to the reconstruction ofSivapithecus positional behavior. Femoral cross-sectional geometry indicates that the shaft was adapted to support mediolaterally directed loading. Femoral condylar asymmetry and a broad but shallow trochlea are distinctly ape-like, revealing capabilities for both rotation and withstanding eccentric loading in the knee. The navicular is characterized by features relating to a broad mid-tarsus and broad distal articulations for the cuneiforms. It also lacks a navicular tubercle as in Pongo. These features suggest that the foot was capable of a powerful grip on large supports, with an inversion/supination capability that would permit foot placement in a variety of positions. The morphology of the new phalanges, including evidence for a relatively large pollex, similarly suggests powerful grasping, consistent with prior evidence from the hallux and tarsus. The functional features of the new specimens permit refinement of previous interpretations of Sivapithecus positional capabilities. They suggest a locomotor repertoire dominated by pronograde activities and also such antipronograde activities as vertical climbing and clambering, but not by antipronograde suspensory activities as practiced by extant apes.     

The problems of the Pliopithecidae as a hylobatid ancestor

Various members of the Pliopithecidae (Pliopithecus, Laccopithecus) and the Proconsulidae (Micropithecus, Dendropithecus, Limnoputhecus, Dionysopithecus, and Platdontopithecus) have been proposed as the ancestral hylobatid (gibbon), based largely on small size and simple-cusped, ape-like molars. However, this ignores evidence presented in early anatomical studies of living brachiating primates. All apes and several South American monkeys show structural anatomical adaptations for brachiation. The Pliopithecidae show some ceboid-like features in the hindlimb which suggest that this genus may have been partly suspensory and possibly comparable to spider monkeys, but without a prehensile tail. They were basically arboreal quadrupedal monkeys without any of the brachiator specializations. Large bodied apes add more traits in order to handle great weight. Among the small-bodied brachiators, only the hylobatids possess these large-brachiator traits. Such modifications serve no purpose other than to support a weight greater than 30 kg. The hylobatid gestation time and longevity are also characteristic only of much larger animals. The ancestral gibbon must have been among the large-bodied sivapithecines. This relationship is supported by body size, geography, and biochemical timing (pliopithecids were probably a distinct lineage in the late Oligocene). If a memeber of the Pliopithecidae were the ancestor of extant hylobatids, it would have had to have grown large, became adapted to brachiation, and then grown small again.Laccopithecus has been newly proposed as the ancestral gibbon. If it is not a member of the pliopithecids, with an age of less than 8 mya, then it could be a fossil hylobatid. It would have had to have separated from the Asian great ape line approximately 15 mya, developed full brachiation, and undergone a reduction in body size and dental sexual dimorphism.     

Normapolles flowers of fagalean affinity from the Late Cretaceous of Portugal

 Exquisitely preserved, charcoalified fossil flowers with in situ pollen of the Normapolles-type from the Late Cretaceous of Portugal are described and a new genus and species of Fagales, Normanthus miraensis, are established. Floral organization and structure of floral organs were studied with scanning electron microscopy and microtome sections. Flowers are actinomorphic, epigynous, and pentamerous; the perianth is simple; stamens alternate with tepals; pollen is oblate and vestibulate; the exine is thick and the tectum is scabrate-microgranulate; the gynoecium is bicarpellate and unilocular; the fruits are probably one-seeded. Comparisons with extant taxa demonstrate that N. miraensis shares many similarities with Fagales and in particular with Betulaceae. However, it is not identical with any extant taxon and cannot be included in any extant family. The combination of characters found in the fossil flowers is congruent with wind-pollination syndromes present in many extant angiosperms and clearly indicates wind-pollination of N. miraensis. Received June 13, 2000 Accepted September 28, 2000     

Pierolapithecus and the functional morphology of Miocene ape hand phalanges: paleobiological and evolutionary implications

The partial skeleton of Pierolapithecus, which provides the oldest unequivocal evidence of orthogrady, together with the recently described phalanges from Pa?alar most likely attributable to Griphopithecus, provide a unique opportunity for understanding the changes in hand anatomy during the pronogrady/orthogrady transition in hominoid evolution. In this paper, we describe the Pierolapithecus hand phalanges and compare their morphology and proportions with those of other Miocene apes in order to make paleobiological inferences about locomotor evolution. In particular, we investigate the orthograde/pronograde evolutionary transition in order to test whether the acquisition of vertical climbing and suspension were decoupled during evolution. Our results indicate that the manual phalanges of Miocene apes are much more similar to one another than to living apes. In particular, Miocene apes retain primitive features related to powerful-grasping palmigrady on the basal portion, the shaft, and the trochlea of the proximal phalanges. These features suggest that above-branch quadrupedalism, inherited from stem hominoids, constituted a significant component of the locomotor repertories of different hominoid lineages at least until the late Miocene. Nonetheless, despite their striking morphological similarities, several Miocene apes do significantly differ in phalangeal curvature and/or elongation. Hispanopithecus most clearly departs by displaying markedly-curved and elongated phalanges, similar to those in the most suspensory of the extant apes (hylobatids and orangutans). This feature agrees with several others that indicate orang-like suspensory capabilities. The remaining Miocene apes, on the contrary, display low to moderate phalangeal curvature, and short to moderately-elongated phalanges, which are indicative of the lack of suspensory adaptations. As such, the transition from a pronograde towards an orthograde body plan, as far as this particular anatomical region is concerned, is reflected only in somewhat more elongated phalanges, which may be functionally related to enhanced vertical-climbing capabilities. Our results therefore agree with the view that hominoid locomotor evolution largely took place in a mosaic fashion: just as taillessness antedated the acquisition of an orthograde body plan, the emergence of the latter—being apparently related only to vertical climbing—also preceded the acquisition of suspensory adaptations, as well as the loss of primitively-retained, palmigrady-related features.