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.     

Additional postcranial remains of omomyid primates from the Uinta Formation, Utah and implications for the locomotor behavior of large-bodied omomyids

Most omomyids are relatively small bodied (e.g. <500 g), but beginning in the middle Eocene, some omomyids began to grow larger. The largest omomyids occur in the late middle Eocene during the Uintan NALMA, reaching an estimated body mass over 1 kg. The hind limb skeleton of small omomyids is relatively well known, and is generally thought to show active arboreal quadrupedal and leaping adaptations. New postcranial specimens of previously unknown elements from the larger Uintan omomyids, Ourayia (two species), Chipetaia lamporea, and Mytonius hopsoni have recently been recovered from the Uinta Formation, Utah, and from the Mission Valley Formation, California, and they provide additional information concerning their locomotor behavior.The new specimens include several distal tibiae, partial calcanei, a complete talus and a proximal first metatarsal of Chipetaia; distal femora, distal tibiae, cuboids, and partial calcanei of Ourayia uintensis; a complete calcaneus of Ourayia sp.; and a partial calcaneus and talus of Mytonius. Metric analysis of these elements, together with qualitative observations of non-metric traits, indicate that Ourayia and Chipetaia show equal or greater development of traits associated with leaping behavior (including elongation of the calcaneus, navicular and cuboid) than do smaller omomyids from North America. The elements of Mytonius, although fragmentary, lack some leaping features that are well-developed in Ourayia and Chipetaia, suggesting that Mytonius may have relied more on arboreal quadrupedal locomotion than on leaping.     

Additional postcranial elements of Teilhardina belgica: The oldest European primate

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.     

Plio-Pleistocene cercopithecids from Kanam East, western Kenya

This paper describes cercopithecid craniodental and postcranial fossils recovered by L. S. B. Leakey at Kanam East, Kenya during the early 1930s. These fossil monkeys have been generally assumed to have been derived from early Pliocene horizons, but their exact geographical and stratigraphical provenience is unknown. Although the question of the evolutionary significance of these specimens must await the recovery of more securely dated material from Kanam East, some general conclusions can be drawn concerning their taxonomic affinities and paleobiology. Based on comparative studies of the craniodental material, at least three extant genera are represented—Colobus,Lophocebus, andCercopithecus. The postcranial fossils include a number of hindlimb specimens, as well as the manubrium of a sternum and a caudal vertebra. Identification of the postcranial remains to particular genera is not possible, but they are similar in morphology to modern arboreal and semiterrestrial cercopithecid monkeys of small to medium size. It is evident that Kanam East had a diverse cercopithecid community, similar to those found today in forested and woodland habitats, and this may be of some significance in reconstructing the paleoecology of the site. Because the fossil record of most extant cercopithecid genera is rather sparse at Plio-Pleistocene sites in Africa, Kanam East represents one of only a few sites that has yielded material that can be assigned toColobus,Lophocebus, orCercopithecus. The fossil monkeys from the site, therefore, provide additional evidence to help reconstruct the paleobiology, as well as the patterns of species diversity and community structure that characterized the cercopithecid radiation during the Plio-Pleistocene.     

Positional behavior of free-ranging Japanese macaques (<Emphasis Type="Italic">Macaca fuscata</Emphasis>)

Positional behavior was quantitatively studied in identified free-ranging Japanese macaques (Macaca fuscata). Five male and 11 female adults were observed in a forested mountain habitat. Data were analyzed for proportion of bout distance, number and time of each locomotion and postural type. Japanese macaques are semiterrestrial, and mainly walk and run quadrupedally. This supports the notion that Macaca are generally quadrupeds. Sex differences in positional behavior were found in the preference of substrate and types of positional behavior. Males and females tend to be terrestrial and arboreal, respectively. Males leap more frequently and longer in distance than do females when they are feeding in trees. These sex differences are considered to be related to differences in morphology, food choice, social activity, and the nursing of infants. Frequencies of leaping and the distance covered by leaping in Japanese macaques are more than those of long-tailed macaques which are arboreal quadrupeds. However, Japanese macaques leap shorter distances at a time than do long-tailed macaques, which indicates that body size may be related to leaping distance more than the frequency of leaping and the distance covered by leaping. Japanese macaques are not as specialized for terrestrial locomotion as pig-tailed macaques. They use both terrestrial and arboreal supports, and are considered to be semi-terrestrial quadrupeds, somewhere between the arboreal long-tailed macaque and the terrestrial pig-tailed macaque. Electronic Publication     

Femoral anatomy of Aegyptopithecus zeuxis,an early Oligocene anthropoid

Three partial femora from Quarries I and M of the early Oligocene Jebel Qatrani Formation in the Fayum of Egypt are attributed to Aegyptopithecus zeuxis on the basis of their appropriate size and anthropoid morphology. Compared with extant catarrhines, Aegyptopithecus is unusual in having a distinct gluteal tuberosity (third trochanter) and a relatively deep distal femoral articulation. In the estimated neck angle, Aegyptopithecus resembles arboreal quadrupeds rather than either leaping or suspensory primates. It seems likely that the femur of this species was relatively robust and short for its body mass. In aspects of its femoral anatomy, Aegyptopithecus is quite different from the parapithecid Apidium and more similar to Catopithecus from late Eocene deposits of the Fayum, and also to small hominoids from the Miocene of East Africa. Am J Phys Anthropol 106:413–424, 1998. © 1998 Wiley-Liss, Inc.     

Skeletal indicators of ecological specialization in pika (Mammalia,Ochotonidae)

Pika species generally fall into two ecotypes, meadow‐dwelling (burrowing) or talus‐dwelling, a classification that distinguishes a suite of different ecological, behavioral, and life history traits. Despite these differences, little morphological variation has previously been documented to distinguish among ecotypes. The aim of this study was to test whether postcranial features related to burrowing are present in meadow‐dwelling species and whether talus‐dwelling species exhibit postcranial modifications related to frequent leaping between rocks. To test this, the scapula, humerus, ulna, radius, innominate, femur, tibia, and calcaneus of 15 species were studied and measured. Twenty‐three measurements were taken on 199 skeletons, and 19 indices were constructed from these measurements. Indices were compared between the two ecotypes using Student's t‐test. Comparisons among ecotypes, species, and subgenera were made using one‐way ANOVA with the Tukey honest significant difference post hoc test. Multivariate results were generated using principal components analyses. Thirteen forelimb and hind limb indices proved significant in distinguishing the meadow‐dwelling, talus‐dwelling, and intermediate forms. A number of these indices are associated with burrowing or leaping in other mammals, providing some support for the hypothesis that postcranial modifications in pika are related to locomotor differences. This evidence of morphological responses to ecological specialization will be useful for reconstructing the paleobiology of extinct taxa, assessing the behavioral variability of extant species, and improving our understanding of the evolutionary history of pikas. J. Morphol., 2013. © 2013 Wiley Periodicals, Inc.     

Species differences in adrenocortical activity of new world primates: Response to dexamethasone suppression

The effect of dexamethasone-induced alteration of adrenocortical activity was assessed in two species of New World primates: Saimiri sciureus and Callicebus moloch. Basal and stress levels of corticosteroids were determined following treatment with three doses of dexamethasone (0, 50, or 500 μg/kg). Saimiri showed substantially higher basal levels of corticosteroids than did Callicebus and a greater incremental corticosteroid response to physical restraint. Dexamethasone was found to reduce basal corticosteroids in both species, although this effect was greater for Callicebus than for Saimiri Moreover, the adrenocortical response to physical restraint was reduced by dexamethasone treatment in Callicebus but not in Saimiri. The pattern of results suggests that the species differ in the mechanisms mediating adrenocortical activity.     

Determination of fetal biparietal diameter without the use of ultrasound in squirrel monkeys

This study evaluated manual caliper measurement of fetal BPD in Saimiri through the abdomen of the dam (TBPD) for correlation with paired ultrasound measurements, prediction of delivery date, subspecies variation, prediction of pregnancy outcome, and correlation between postpartum BPD and TBPD. Regression analysis revealed a close relationship between TBPD measurements and those obtained by ultrasound (P < 0.001). TBPD for Saimiri boliviensis boliviensis increased from a mean of 14.8 ± 0.3 mm for 11 weeks prepartum to a delivery week measurement of 33.2 ± 0.2mm. Delivery-week TBPD of Saimiri boliviensis peruviensis were significantly smaller than Saimiri sciureus sciureus (P < .05). Delivery week TBPD had a correlation coefficient of 0.64 with paired post-patrum measurements. No complications were associated with the technique. Delivery date could be predicted within two weeks. TBPD is an inexpensive, safe, rapid method of approximating fetal growth during the last half of pregnancy in Saimiri.     

Morphological and Genetic Characterization of <Emphasis Type="Italic">Saimiri boliviensis</Emphasis>

The taxonomy of Saimiri is controversial because morphological characteristics, traditionally used for identification, are insufficient to distinguish species and subspecies. Genetic studies of specimens become relevant for captive management, especially considering their frequently unknown geographical origin. We analyzed phenotypic and genetic parameters in Saimiri spp. in Argentinean zoological gardens and biological stations to provide a more accurate taxonomic identification. We studied 27 males and 19 females of Saimiri spp. The cytogenetic analysis in mitotic metaphases corroborated a modal number of 2N = 44, XX/XY, and FN = 75 for males and FN = 76 for females. G- and C-bands, fluorescence in situ hybridization (FISH) and the pelage coloration pattern of all the specimens corresponded to Saimiri boliviensis boliviensis. We characterized for the first time the sperm cell morphology and morphometry (mean ± SE): total length: 71.39 ± 5.40 μm; head length: 5.71 ± 0.81 μm; head width: 3.76 ± 0.70 μm; acrosome length: 3.70 ± 0.82 μm; midpiece length: 12.20 ± 2.22 μm. Researchers can use the characterization of the sperm morphology as another parameter for taxonomic identification that, together with cytogenetic and molecular ones, would allow a more precise identification of individual Saimiri boliviensis boliviensis.     

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.     

A study of postnatal appendicular skeletal maturation in captive-born squirrel monkeys (Saimiri boliviensis)

This study is based on a mixed longitudinal radiographic sampling of appendicular bones in 82 captive-born squirrel monkeys (Saimiri boliviensis). All appendicular ossification centers had appeared radiographically by 17 weeks of age, and epiphyseal fusion was complete by 47-53 months of age. No statistically significant differences were found between the sexes in comparisons carried out at birth and at 6 and 8 months of age. Valid sex comparisons could not be made at other ages owing to the small size of the sample. The sequence of appearance of the ossification centers (Spearman correlation coefficient of Saimiri vs. Callithrix = 0.68) shows greater interspecies differences than the sequence of fusion (Saimiri vs. Callithrix = 0.88).     

Observations on two types of neotropical primate intertaxa associations

During a socioecological field study of Colombian spider monkeys, data were collected on spatial associations and social and ecological interactions among free-ranging Ateles belzebuth, Alouatta seniculus, Cebus apella, and Saimiri sciureus. The most frequently observed associations occurred between groups of squirrel and capuchin monkeys. Saimiri-Cebus associations were seen at all times of day and year, but no intertaxa play, passive body contact, or grooming interactions were observed. The Saimiri-Cebus association was paralleled by one between Saimiri and the small hawk, Harpagus bidentatus, and sometimes other insectivorous birds. These associations may be based in part on a complex balance of both mutual and one-sided foraging advantages. Less frequent associations between Ateles and Alouatta were based on mutual attraction to specific fruiting trees or contacts occurring on travel routes. Unlike the more frequently observed associations between Saimiri and Cebus, those between Ateles and Alouatta included both positive and negative interactions; for example, mutual play, grooming, and olfactory investigation as well as threats, chases, and supplantations.     

Captive breeding of squirrel monkeys,Saimiri sciureus and Saimiri boliviensis: The problem of hybrid groups

The electrophoretic variability of blood proteins coding for up to 32 genetic loci was analyzed in 108 squirrel monkeys (Saimiri sciureus, Saimiri boliviensis, hybrids) from two captive colonies. Twelve polymorphic loci with 31 alleles are reported. The biallelic Ada* locus, G-statistics and Hardy-Weinberg genotype equilibria are useful for recognizing hybrids between S. sciureus and S. boliviensis. Backcrosses in hybrid stocks and gene flow in a natural hybrid belt, however, complicate the taxonomic diagnosis of captive specimens: S. sciureus phenotypes imported from Peru possessed the allele Ada*132, which generally characterizes S. boliviensis (or species hybrids). The complex taxonomy of Saimiri spp. Requires careful planning of captive breeding. We suggest a genetic analysis of the founder individuals before their inclusion in the European studbook population and to breed S. sciureus from Guyana separately from Peruvian imports, because the latter bear a greater risk of being taxonomically heterogeneous. Zoo Biol 17:95–109, 1998. © 1998 Wiley-Liss, Inc.     

Locomotor Behavior and Body Mass of Paramys delicatus (Ischyromyidae,Rodentia) and Commentary on Other Early North American Paramyines

Paramyine ischyromyids are one of the first ancestral rodent groups to appear in North America. Studying ecological indicators of these extinct animals enables us to better understand how they integrated into North American mammalian communities. In this study we reassess the locomotor behavior of a nearly complete skeleton of a paramyine, Paramys delicatus (AMNH FM 12506), using functional limb indices and living squirrels as extant analogues. We then used the results of the functional limb index study to select an appropriate locomotor group for body mass estimations of Paramys delicatus and other early North American (Wasatchian-Bridgerian) paramyines. This was done because body mass is strongly tied to locomotor patterns and more reliable body mass estimates can be generated from an extant sample that functionally resembles the fossils being studied. Functional limb indices were calculated for three locomotor groups (arboreal, semifossorial, and gliding) of living sciurids. Comparisons among arboreal, semifossorial, and gliding sciurids show that the functional indices related to mechanical advantage of muscles and limb robusticity enable distinction among locomotor groups; however, there is considerable overlap between arboreal and semifossorial taxa. Paramys delicatus was found to have generally greater mechanical advantages and limb robusticity than most living squirrels, including semifossorial taxa. As these traits are associated with semifossorial squirrels that frequently use scratch-digging, this suggests that Paramys delicatus and perhaps other early paramyines were likely proficient scratch-diggers. However, indices reflecting limb proportions of paramyines suggest that these early rodents may have used more hind limb dominated locomotion than do living squirrels. Body mass estimations for early paramyines were therefore derived from a semifossorial squirrel sample. Statistical comparisons suggest that many of the most reliable estimators for body mass in Paramys delicatus and other paramyines are those derived from humeral dimensions, with the most reliable estimate being humeral head superoinferior breadth. Using these estimators, individual body mass estimates of early paramyines range from 3391 to 4005 g for Paramys delicatus, 1137–1329 g for Paramys copei, 1291 g for Paramys taurus, and 3357 g for Notoparamys costilloi. All body mass estimations derived from postcranial elements are substantially larger than previously published estimates derived from the dentition, which may be because postcranial elements play a larger role in supporting body weight.

     

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.     

Fossil penguin (Aves: Sphenisciformes) cranial material from the Eocene of Seymour Island (Antarctica)

Our knowledge of the cranial morphology of early penguins remains poor, particularly for Paleogene taxa. This paper describes a partial penguin skull and additional isolated cranial elements from the Eocene La Meseta Formation of Seymour Island, Antarctica. These specimens cannot be assigned to named taxa at present, but there is a strong possibility they belong to La Meseta penguins known only from postcranial elements. The skull shares extensive dorsal development of the temporal fossae with extant and fossil Spheniscus and the fossil penguins Paraptenodytes and Marplesornis, indicating the adductor complex was powerful in early penguins. Partial mandibles belonging to a much larger penguin are similar to Paraptenodytes and differ from all living penguins in the lack of a hooked medial process of the articular and the presence of a foramen anterior to the mandibular cotyles. Given the rarity of penguin cranial remains, these specimens provide important new insight into early penguin evolution.