Gabriel S YapuncichDuke University School of Medicine · Medical Education Administration
Gabriel S Yapuncich
PhD
About
61
Publications
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Introduction
Additional affiliations
July 2018 - June 2021
July 2017 - June 2018
January 2013 - April 2017
Education
January 2013 - May 2017
August 2011 - December 2012
September 2008 - May 2011
Publications
Publications (61)
Adaptive scenarios of crown primate origins remain contentious due to uncertain order of acquisition and functional significance of the clade’s diagnostic traits. A feature of the talus bone in the ankle, known as the posterior trochlear shelf (PTS), is well-regarded as a derived crown primate trait, but its adaptive significance has been obscured...
Scientific study of lemurs, a group of primates found only on Madagascar, is crucial for understanding primate evolution. Unfortunately, lemurs are among the most endangered animals in the world, so there is a strong impetus to maximize as much scientific data as possible from available physical specimens. MicroCT scanning efforts at Duke Universit...
An accurate prediction of the body mass of an extinct species can greatly inform the reconstruction of that species' ecology. Therefore, paleontologists frequently predict the body mass of extinct taxa from fossilized materials, particularly dental dimensions. Body mass prediction has traditionally been performed in a frequentist statistical framew...
The Paleogene epoch was a dynamic time for mammalian evolution, including the fossil relatives of primates. Several adaptively significant features of the primate foot first appear in fossils from the Paleogene, and relatives of most extant primate groups are recognizable in the fossil record by the end of the Oligocene. This chapter reviews the mo...
Morphological traits suggesting powerful jumping abilities are characteristic of early crown primate fossils. Because tree squirrels lack certain ‘primatelike’ grasping features but frequently travel on the narrow terminal branches of trees, they make a viable extant model for an early stage of primate evolution. Here, we explore biomechanical dete...
Jumping is a crucial behavior in fitness-critical activities including locomotion, resource acquisition, courtship displays, and predator avoidance. In primates, paleontological evidence suggests selection for enhanced jumping ability during their early evolution. However, our interpretation of the fossil record remains limited, as no studies have...
Though leaping is considered critical for strepsirrhine evolution, we lack sufficient leaping performance data to evaluate its adaptive role. Here, we examine vertical jumping agility (VJA) in four strepsirrhine species at the Duke Lemur Center: a specialized leaper (Propithecus coquereli, ~ 4.13 kg), two intermediate leapers (Varecia variegata, ~...
In many primate species, leaping behavior is crucial for crossing gaps in the canopy, escaping predators, and capturing prey. We investigate vertical leaping – used here as a measure of leaping potential that can be applied to horizontal leaps as well – in two platyrrhines: Saguinus bicolor (n = 2, 20 leaps) and Callimico goeldii (n = 3, 24 leaps)....
Leaping is an important locomotor behavior for arboreal taxa such as primates, providing means to cross discontinuous substrates, escape predation, and/or capture prey. Primates that leap frequently have relatively longer hindlimbs than those taxa that leap less often. However, it is unknown if this pattern holds across a broader phylogenetic sampl...
Objectives:
The competing functional demands of diarthrodial joints, permitting mobility while retaining enough stability to transmit forces across the joint, have been linked with the shape and size of the joint's articular surfaces. A clear understanding of the relationship between joint morphology and joint movement potential is important for r...
A primate's body mass covaries with numerous ecological, physiological, and behavioral characteristics. This versatility and potential to provide insight into an animal's life has made body mass prediction a frequent and important objective in paleoanthropology. In hominin paleontology, the most commonly employed body mass prediction equations (BMP...
Scientific study of lemurs, a group of primates found only on Madagascar, is crucial for understanding primate evolution. Unfortunately, lemurs are among the most endangered animals in the world, so there is a strong impetus to maximize as much scientific data as possible from available physical specimens. MicroCT scanning efforts at Duke Universit...
Given that most species of primates are predominantly arboreal, maintaining the ability to move among branches of varying sizes has presumably been a common selective force in primate evolution. However, empirical evaluations of the relationships between morphological variation and characteristics of sub-strate geometry, such as substrate diameter...
Objectives:
The femoral remains recovered from the Lesedi Chamber are among the most complete South African fossil hominin femora discovered to date and offer new and valuable insights into the anatomy and variation of the bone in Homo naledi. While the femur is one of the best represented postcranial elements in the H. naledi assemblage from the...
We present a group-wise shape correspondence method for analyzing variable and complex objects in a population study. The proposed method begins with the standard spherical harmonics (SPHARM) point distribution models (PDM) with their spherical mappings. In case of complex and variable objects, the equal area spherical mapping based SPHARM correspo...
Objectives:
Predicting body mass is a frequent objective of several anthropological subdisciplines, but there are few published methods for predicting body mass in immature humans. Because most reference samples are composed of adults, predicting body mass outside the range of adults requires extrapolation, which may reduce the accuracy of predict...
Automated geometric morphometric methods are promising tools for shape analysis in comparative biology, improving researchers' abilities to quantify variation extensively (by permitting more specimens to be analyzed) and intensively (by characterizing shapes with greater fidelity). Although use of these methods has increased, published automated me...
Songhor is an early Miocene fossil locality in Kenya known for its diverse primate assemblage that includes catarrhine species belonging to the genera Kalepithecus, Limnopithecus, Dendropithecus, Rangwa-pithecus, and Proconsul. Expeditions to Songhor since the 1930s have recovered unassociated catarrhine postcranial remains from both the fore-and h...
Body mass is an ecologically and biomechanically important variable in the study of hominin biology. Regression equations derived from recent human samples allow for the reasonable prediction of body mass of later, more human-like, and generally larger hominins from hip joint dimensions, but potential differences in hip biomechanics across hominin...
Since body mass covaries with many ecological aspects of an animal, body mass prediction of fossil taxa is a frequent goal of paleontologists. Body mass prediction often relies on a body mass prediction equation (BMPE): a bivariate relationship between a predictor variable (e.g., molar occlusal area, femoral head breadth) and body mass as observed...
Three-dimensional geometric morphometrics (3DGM) has become a standard method for describing and analyzing shape variation in the primate skeleton. One promising application of 3DGM is the production of phenetic dendrograms in order to examine patterns of shared morphology and potentially shared evolutionary history. However, because 3DGM is often...
Objective:
On the talus, the position and depth of the groove for the flexor hallucis longus tendon have been used to infer phylogenetic affinities and positional behaviors of fossil primates. This study quantifies aspects of the flexor hallucis longus groove (FHLG) to test if: (1) a lateral FHLG is a derived strepsirrhine feature, (2) a lateral F...
Smaers, Mongle & Kandler (2016) (Biological Journal of the Linnean Society, 118: 74–98) introduced a new phylogenetic comparative method, multiple-variance Brownian motion (mvBM), for reconstructing ancestral states given a phylogenetic tree and continuous trait data. The authors conducted a simulation study and argued that mvBM outperforms constan...
Automated geometric morphometric methods are promising tools for shape analysis in comparative biology: they improve researchers' abilities to quantify biological variation extensively (by permitting more specimens to be analyzed) and intensively (by characterizing shapes with greater fidelity). Although use of these methods has increased, automate...
Body mass prediction is a frequent goal of paleontologists since body mass covaries with many aspects of a species' ecology. For example, niche partitioning by body mass (as predicted from tooth size) is often invoked in mammalian paleocommunities. However, tooth size can vary independent of body mass, and this variation has important ecological im...
To understand the hand of living primates from an adaptive perspective, data on the morphological pattern of the earliest primates is required. This chapter discusses what is known about the early evolution of primate hands based on fossils of Paleogene plesiadapiforms (potential stemprimates), adapiforms, omomyiforms, and anthropoids. Implications...
Primate species typically differ from other mammals in having bony canals that enclose the branches of the internal carotid artery (ICA) as they pass through the middle ear. The presence and relative size of these canals varies among major primate clades. As a result, differences in the anatomy of the canals for the promontorial and stapedial branc...
Well-preserved crania of notharctine adapiforms from the Eocene of North America provide the best
direct evidence available for inferring neuroanatomy and encephalization in early euprimates (crown
primates). Virtual endocasts of the notharctines Notharctus tenebrosus (n = 3) and Smilodectes gracilis
(n = 4) from the middle Eocene Bridger formation...
Smaers, Mongle & Kandler (2016) (Biological Journal of the Linnean Society, 118: 78-94) introduced a new phylogenetic comparative method, multiple variance Brownian motion (mvBM), for reconstructing ancestral states given a phylogenetic tree and continuous trait data. The authors conducted a simulation study and argued that mvBM outperforms constan...
Because body mass is correlated with many aspects of an animal’s ecology (Peters, 1983; Fleagle, 1985; McNab, 1990), predicting body mass in extinct or extant animals is a frequent goal of paleontologists and neontologists (Kay and Simons, 1980; Gingerich et al., 1982; Dagosto and Terranova, 1992; Mendoza et al., 2006; Yapuncich et al., 2015). Alth...
Based on passive joint mobility, lorisids can achieve higher degrees of pedal inversion and eversion than other strepsirrhines. However, initial assessments of curvature of the talar ectal facet suggest this component of the subtalar joint is noticeably flatter among lorisids than other strepsirrhines. Flatter joint surfaces have been associated wi...
Phylogenetic comparative methods (PCMs) use data on species traits and phylogenetic relationships to shed light on evolutionary questions. Recently, Smaers and Vinicius suggested a new PCM, Independent Evolution (IE), which purportedly employs a novel model of evolution based on Felsenstein's Adaptive Peak Model. The authors found that IE improves...
Although variation in cranial arterial presence, route and development has been
shown to provide indications of phylogenetic relationship in primates, information on
relative area of the promontorial and stapedial bony canals has never been
comprehensively quantified. Among fossil euprimates, some genera (notably Mahgarita,
Notharctus, and Rooneyia...
Some articular surfaces of the primate talus have been shown to scale with positive allometry, particularly the ectal and fibular facets. These scaling relationships may indicate increased demand for the stability at the joint, or the ability to transmit force without displacement or failure. Altering the shape of the facet could also facilitate st...
On the talus, the position of the groove for the tendon of the flexor fibularis muscle, a plantarflexor of the foot and flexor of the digits, has been used to differentiate strepsirrhine and haplorhine primates. Extant strepsirrhines, which more frequently employ abducted foot postures, have a laterally shifted flexor fibularis groove (FFG). Among...
Objective:
Multiple meaningful ecological characterizations of a species revolve around body mass. Because body mass cannot be directly measured in extinct taxa, reliable body mass predictors are needed. Many published body mass prediction equations rely on dental dimensions, but certain skeletal dimensions may have a more direct and consistent re...
Objectives:
Comprehensive quantification of the shape and proportions of the medial tibial facet (MTF) of the talus (=astragalus) has been lacking for Primates and their closest relatives. In this study, aspects of MTF form were quantified and employed to test hypotheses about their functional and phylogenetic significance. The following hypothese...
Three-dimensional geometric morphometric (3DGM) methods for placing landmarks on digitized bones have become increasingly sophisticated in the last 20 years, including greater degrees of automation. One aspect shared by all 3DGM methods is that the researcher must designate initial landmarks. Thus, researcher interpretations of homology and corresp...
As animals increase in size, they reduce use of flexed-limb in favor of extended-limb postures, trading decreased joint mobility for increased stability and stress-reduction. Greater mobility has been associated with greater facet curvature. Therefore, allometric postural differences should also correlate with curvature: larger animals should have...
Presence, route, and development of cranial arterial pathways have been shown to provide indications of relative ancestry and relationships in primates even though canal size does not necessarily correlate with artery size. Information on relative area of the promontorial and stapedial bony canals has never been comprehensively quantified for stati...
Distinctive differences in talar morphology are widely recognized to separate anthropoids, tarsiiforms, and strepsirrhines, including the relative size of the medial tibial facet. Expanded medial tibial facet area among “prosimians” has been related to postural behaviors that transmit a greater percentage of body mass through the facet. While this...
Questions surrounding the origin and early evolution of primates continue to be the subject of debate. Though anatomy of the skull and inferred dietary shifts are often the focus, detailed studies of postcrania and inferred locomotor capabilities can also provide crucial data that advance understanding of transitions in early primate evolution. In...
The articular facets of interosseous joints must transmit forces while maintaining relatively low stresses. To prevent overloading, joints that transmit higher forces should therefore have larger facet areas. The relative contributions of body mass and muscle-induced forces to joint stress are unclear, but generate opposing hypotheses. If mass-indu...
Body mass is a fundamental descriptor of an animal's ecology. For fossil species, reliable body mass estimations provide avenues for understanding an extinct species' ecological and behavioral profile. Since the last comprehensive analysis using tarsal elements for estimating primate body mass, there have been substantial increases in fossil specim...
The articular facets of synovial joints must transmit forces while maintaining relatively low stresses. Joints that transmit higher forces should therefore have larger facet areas to prevent overloading. The relative contributions of body mass and muscle-induced forces to joint stress are unclear, but generate opposing hypotheses. If mass-induced f...
Extinct Multituberculata was the longest surviving order of mammals. Given their near ubiquity in Mesozoic and Cenozoic communities, reconstructing their paleoecology is important for a balanced view of mammalian evolutionary history. The relative lack of multituberculate postcrania has hindered the study of their functional morphology and the impl...
It has long been recognized that Paleocene-Eocene plagiomenids have derived dentitions similar to extant flying lemurs. These affinities have led to their classification within Dermoptera, although discoveries of a plagiomenid basicranium and teeth of Eocene dermopterans in Asia seem to contradict this relationship. Here we describe the first denta...