Frequent Leaping Research Articles

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.

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

AbstractCover illustration. Collared pika (Ochotona collaris) is caught mid‐leap on a foraging bout by wildlife photographer Moose Peterson. In this issue of the Journal of Morphology Reese, Lanier, and Sargis study whether postcranial features related to burrowing are present in meadow‐dwelling species and whether talus‐dwelling species (like the one on the cover) exhibit postcranial modifications related to frequent leaping between rocks (pages 585–602).

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.

Functional morphology of the postcranium and locomotor behavior of Neosaimiri fieldsi, a Saimiri‐like Middle Miocene platyrrhine

A number of postcranial specimens of Neosaimiri fieldsi, a Middle Miocene platyrrhine, were discovered in 1988, 1989, and 1990 at La Venta, Colombia. Until recently only three postcranial specimens of this species had been discovered and the present material adds further information about this taxon's postcranial morphology. In overall skeletal dimensions and in postcranial features, Neosaimiri is most similar to Saimiri among extant medium-sized platyrrhines, but differs from Saimiri in having more rugose surface markings, a longer olecranon, a smaller anterior process of the distal tibia, an absence of a distal surface extension on the anterior tibial shaft, an absence of an anterior midtrochlear depression of the talus, and a shorter distal calcaneus relative to the calcaneal tuberosity. These differences suggest that Neosaimiri was relatively heavily built, possessed a more dominant forelimb in quadrupedal progression, and utilized a less stabilized upper ankle joint, and a shorter power arm for plantarflexion. Neosaimiri is interpreted as an arboreal quadruped with frequent leaping across arboreal gaps, as in extant Saimiri, with perhaps less frequent running and leaping than in Saimiri. As with the dentition, the postcranial specimens suggest the close relationship between Neosaimiri and extant Saimiri. Am J Phys Anthropol 102:515–544, 1997. © 1997 Wiley-Liss, Inc.

Feeding and ranging in the Mentawai Island langur (Presbytis potenziani)

Presbytis potenziani is found only on the Mentawai Islands, Indonesia, and its ecology and feeding and ranging behavior have been little studied. I studied 10 groups ofPresbytis potenziani in the primary forests of North Pagai Island, Mentawai, Indonesia.P. potenziani used primarily the upper strata of the forests for feeding, movement, and resting. Groups remained cohesive during their daily activities, ranged between 100 to > 1000 m daily, and occupied home ranges of ≤ 40 ha. Neither sex predominantly initiated group movement. Locomotion was primarily quadrupedal, with frequent leaping. P. potenziani showed two feeding peaks, one in early morning and one during midafternoon. P. potenziani fed mainly on climbers and trees of the Dipterocarpaceae. They ate primarily leaves, but also fed on fruits and other plant parts.

Proximal femoral anatomy of omomyiform primates

Abstract Compared to the adapid primates, the limb skeleton of omomyiforms is only poorly represented. With the discovery of some new material, the proximal femur is now known in several taxa, including representatives from both of the recognized families. We describe the femur of a very small North American omomyid from the Bridger formation (middle Eocene) and compare its anatomy with the omomyine Hemiacodon and the European microchoerids Nannopithex , Necrolemur and Microchoerus. Tarsius and omomyiforms share several features of the proximal femur which are correlated with frequent leaping in small primates, and which may be morphotypic for Tarsiiformes. Hemiacodon and the new small omomyid are quite similar to each other in that they both have a semicylindrical femoral head which, although more advanced than most primates, is not as derived as the fully cylindrical form exhibited by galagos and tarsiers. As with other areas of the postcranium, microchoerids are very distinct from North American omomyiforms. Microchoerus and Necrolemur exhibit features which are otherwise seen primarily in anthropoid primates such as a marked posterior projection of the lesser trochanter. In addition, Necrolemur shares a unique construction of the intertrochanteric crest with parapithecids. Despite these and other intriguing similarities of the postcranial skeleton, any relationship between microchoerids and early anthropoids is difficult to establish because of other marked differences between them.

Description of new skeletal remains of the early Eocene anaptomorphine primate Absarokius (Omomyidae) and a discussion about its adaptive profile

The early Eocene anaptomorphine Absarokius abbotti has previously been represented solely by dental remains. Recent field work in the Washakie Basin, southcentral Wyoming has yielded four skeletal elements attributable to this taxon: a distal humerus, a partial tibia, a talus, and a calcaneus. As expected, these elements are characterized by the euprimate morphotypic features shared by adapids and omomyids. These include a cylindrical humeral trochlea separated from a spherical capitulum by a distinct groove, a high talar trochlear body with medial and lateral margins of equal height, a long talar neck, an ovoid talar head, an anteriorly elongated calcaneus, a reduced calcaneal peroneal tubercle, and a pivotal calcaneocuboid articulation. Specializations beyond the euprimate morphotype include some additional anterior calcaneal elongation and an extensive and strong distal tibiofibular articulation. These specializations, along with other anatomical features, suggest an arboreal habitus that included frequent leaping for Absarokius . The specialized features of the tibia and calcaneus of Absarokius occur among a number of extant primate clades and thus are of limited use in determining phylogenetic relationships. Analysis of the shear crests on M2 of this small creature indicates that it was predominantly frugivorous and the relative size of its orbit as preserved on a number of maxillary fragments indicates that it probably had a nocturnal activity cycle.

Ontogenetic scaling of skeletal proportions in the talapoin monkey

The talapoin monkey is distinct from its close relatives in the genus Cercopithecus in a variety of morphological and ecological features, inclining some to place it in its own genus, Miopithecus . It is also the smallest of the extant catarrhines, and in this investigation the extent to which the morphological distinctions of the talapoin monkey are the result of allometric factors is analysed. A series of cranial and postcranial measurements were taken on the skeletons of young and adult talapoin monkeys ( C. talapoin ) and moustached monkeys ( C. cephus ). Ontogenetic scaling (i.e., allometric extrapolation) was utilized as a criterion of substraction in both bivariate and multivariate comparative allometric analysis. Adult cranial and postcranial proportions do differ significantly between C. talapoin and C. cephus , but in almost all cases these adult shape differences result from the sharing of common underlying patterns of ontogenetic allometry. Use of additional data from Verheyen's (1962) monograph suggests that the marked differences in skull form within the Cercopithecus group (from talapoin to patas monkeys) may also be primarily a product of ontogenetic scaling. The specific postcranial proportions seen in adult talapoins do not accord with expectations derived from several recent biomechanical models for primates which engage in frequent leaping and climbing behaviors, though the comparative growth allometric perspective utilized here does clarify these adult shape differences. The predominantly paedomorphic morphology of the talapoin monkey appears to be a direct and correlated allometric consequence of a decrease in overall growth rates and terminal body size, which may be related to increased propensities for leaping behavior and a more insectivorous diet.

The biology of Euryattus sp. indet., a web‐building jumping spider (Araneae, Salticidae) from Queensland: utilization of silk, predatory behaviour and intraspecific interactions

The biology of an aberrant saltioid spider, Euryattus Thorell sp. indet., is described from observations in a Queensland rain forest and the laboratory. Pronounced morphological and behavioural changes occur during post‐embryological development. Juveniles spin webs, but adult females make ‘suspension nests’ by suspending a curled‐up leaf by heavy guylines from a rock ledge or vegetation. Adult males spin neither webs nor suspension nests. Females oviposit inside their suspension nests, but if denied access to leaves for suspension, they spin and oviposit in webs similar to those spun by juveniles. The flat, papery egg sacs of Euryattus are atypical for a salticid, being more like the egg sacs of many of the Gnaphosidae. Intraspecific display behaviour has characteristics in common with typical salticids, but also includes unique features. Male courtship includes vibratory displays performed on the surface of the suspended leaf. Mating occurs inside the curled‐up leaf. Males co‐habit with sub‐adult females in suspension nests. Females take over suspension nests of other females and eat each other's eggs. Normal locomotion, intraspecific interactions, and predatory behaviour are characterized by frequent leaping. Euryattus routinely makes long and accurate leaps on to prey, including flying insects intercepted in mid‐air and spiders and insects located in alien webs. The phylogenetic implications of the unusual characteristics of Euryattus are considered.