Comparative 3D quantitative analyses of trapeziometacarpal joint surface curvatures among living catarrhines and fossil hominins

Comparisons of joint surface curvature at the base of the thumb have long been made to discern differences among living and fossil primates in functional capabilities of the hand. However, the complex shape of this joint makes it difficult to quantify differences among taxa. The purpose of this study is to determine whether significant differences in curvature exist among selected catarrhine genera and to compare these genera with hominin¹ fossils in trapeziometacarpal curvature. Two 3D approaches are used to quantify curvatures of the trapezial and metacarpal joint surfaces: (1) stereophotogrammetry with nonuniform rational B‐spline (NURBS) calculation of joint curvature to compare modern humans with captive chimpanzees and (2) laser scanning with a quadric‐based calculation of curvature to compare modern humans and wild‐caught Pan, Gorilla, Pongo, and Papio. Both approaches show that Homo has significantly lower curvature of the joint surfaces than does Pan. The second approach shows that Gorilla has significantly more curvature than modern humans, while Pongo overlaps with humans and African apes. The surfaces in Papio are more cylindrical and flatter than in Homo. Australopithecus afarensis resembles African apes more than modern humans in curvatures, whereas the Homo habilis trapezial metacarpal surface is flatter than in all genera except Papio. Neandertals fall at one end of the modern human range of variation, with smaller dorsovolar curvature. Modern human topography appears to be derived relative to great apes and Australopithecus and contributes to the distinctive human morphology that facilitates forceful precision and power gripping, fundamental to human manipulative activities. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc. ¹ The term “hominin” refers to members of the tribe Hominini, which includes modern humans and fossil species that are related more closely to modern humans than to extant species of chimpanzees, Wood and Lonergan (2008). Hominins are in the family Hominidae with great apes.     

Ectocranial suture fusion in primates: pattern and phylogeny

Patterns of ectocranial suture fusion among Primates are subject to species‐specific variation. In this study, we used Guttman Scaling to compare modal progression of ectocranial suture fusion among Hominidae (Homo, Pan, Gorilla, and Pongo), Hylobates, and Cercopithecidae (Macaca and Papio) groups. Our hypothesis is that suture fusion patterns should reflect their evolutionary relationship. For the lateral‐anterior suture sites there appear to be three major patterns of fusion, one shared by Homo‐Pan‐Gorilla, anterior to posterior; one shared by Pongo and Hylobates, superior to inferior; and one shared by Cercopithecidae, posterior to anterior. For the vault suture pattern, the Hominidae groups reflect the known phylogeny. The data for Hylobates and Cercopithecidae groups is less clear. The vault suture site termination pattern of Papio is similar to that reported for Gorilla and Pongo. Thus, it may be that some suture sites are under larger genetic influence for patterns of fusion, while others are influenced by environmental/biomechanic influences. J. Morphol. 275:342–347, 2014. © 2013 Wiley Periodicals, Inc.     

“Lucy” (A.L. 288‐1) had five sacral vertebrae

A “long‐backed” scenario of hominin vertebral evolution posits that early hominins possessed six lumbar vertebrae coupled with a high frequency of four sacral vertebrae (7:12‐13:6:4), a configuration acquired from a hominin‐panin last common ancestor (PLCA) having a vertebral formula of 7:13:6‐7:4. One founding line of evidence for this hypothesis is the recent assertion that the “Lucy” sacrum (A.L. 288‐1an, Australopithecus afarensis) consists of four sacral vertebrae and a partially‐fused first coccygeal vertebra (Co1), rather than five sacral vertebrae as in modern humans. This study reassesses the number of sacral vertebrae in Lucy by reexamining the distal end of A.L.288‐1an in the context of a comparative sample of modern human sacra and Co1 vertebrae, and the sacrum of A. sediba (MH2). Results demonstrate that, similar to S5 in modern humans and A. sediba, the last vertebra in A.L. 288‐1an exhibits inferiorly‐projecting (right side) cornua and a kidney‐shaped inferior body articular surface. This morphology is inconsistent with that of fused or isolated Co1 vertebrae in humans, which either lack cornua or possess only superiorly‐projecting cornua, and have more circularly‐shaped inferior body articular surfaces. The level at which the hiatus' apex is located is also more compatible with typical five‐element modern human sacra and A. sediba than if only four sacral vertebrae are present. Our observations suggest that A.L. 288‐1 possessed five sacral vertebrae as in modern humans; thus, sacral number in “Lucy” does not indicate a directional change in vertebral count that can provide information on the PLCA ancestral condition. Am J Phys Anthropol 156:295–303, 2015. © 2014 Wiley Periodicals, Inc.     

Phylogenetic Separation in Limb Use in Captive Gibbons (Hylobatidae): A Comparison Across the Primate Order

Although there have been few studies of self‐scratching in primates, some have reported distinct differences in whether hands or feet are used, and these variations seem to reflect the evolutionary history of the Order. Monkeys and prosimians use both hands and feet to self‐scratch while African great apes use hands almost exclusively. Gibbons represent an evolutionary divergence between monkeys and great apes and incidental observations at the Gibbon Conservation Center pointed to a difference in self‐scratching among the four extant gibbon genera (Hoolock, Nomascus, Symphalangus, and Hylobates). To validate and further explore these preliminary observations, we collected systematic data on self‐scratching from 32 gibbons, including nine species and all four genera. To supplement gibbon data, we also collected self‐scratching information from 18 great apes (four species), five prosimians (two species), 26 New World Monkeys (nine species) and 20 Old World Monkeys (seven species). All monkeys and some prosimians used both hands and feet to self‐scratch, whereas one prosimian species used only feet. All African great apes used hands exclusively (orangutans were an exception displaying occasional foot‐use). This appears to represent a fundamental difference between monkeys and great apes in limb use. Interestingly, there was a clear difference in self‐scratching between the four gibbon genera. Hylobates and Symphalangus self‐scratched only with hands (like all African great apes), while Hoolock and Nomascus self‐scratched with both hands and feet (like monkeys and prosimians). This difference in gibbon behavior may reflect the evolutionary history of gibbons as Hoolock and Nomascus are thought to have evolved before both Hylobates and Symphalangus. What evolutionary pressures led to this divergent pattern is currently opaque; however, this shift in limb preference may result from niche separation across the order facilitating differences in the behavioral repertoire associated with hind and forelimbs. Am. J. Primatol. 74:1035‐1043, 2012. © 2012 Wiley Periodicals, Inc.     

Sex differences in anthropoid mandibular canine lateral enamel formation

Previous research has demonstrated that great ape and macaque males achieve large canine crown sizes primarily through extended canine growth periods. Recent work has suggested, however, that platyrrhine males may achieve larger canine sizes by accelerating rather than prolonging growth. This study tested the hypothesis that the ontogenetic pathway leading to canine sexual dimorphism in catarrhines differs from that of platyrrhines. To test this hypothesis, males and females of several catarrhine genera (Hylobates, Papio, Macaca, Cercopithecus, and Cercocebus) and three platyrrhine genera (Cebus, Ateles, and Callicebus) were compared in the number and spacing of perikymata (enamel growth increments) on their canine crowns. In addition, perikymata periodicities (the number of days of growth perikymata represent) were determined for five genera (Hylobates, Papio, Macaca, Cebus, and Ateles) using previously published as well as original data gathered for this study. The central findings are as follows: 1) males have more perikymata than females for seven of eight genera (in five of the seven, the differences are statistically significant); 2) in general, the greater the degree of sexual dimorphism, the greater the sex difference in male and female perikymata numbers; 3) there is no evidence of a systematic sex difference in primate periodicities; and 4) there is some evidence that sex differences in enamel formation rates may make a minor contribution to canine sexual dimorphism in Papio and Cercopithecus. These findings strongly suggest that in both catarrhines and platyrrhines prolongation of male canine growth is the primary mechanism by which canine crown sexual dimorphism is achieved. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.     

Placement of the diaphragmatic vertebra in catarrhines: implications for the evolution of dorsostability in hominoids and bipedalism in hominins

A fundamental adaptation to orthograde posture and locomotion amongst living hominoid primates is a numerically reduced lumbar column, which acts to stiffen the lower back and reduce injuries to the intervertebral discs. A related and functionally complementary strategy of spinal stability is a caudal position of the diaphragmatic vertebra relative to the primitive condition found in nonhominoid primates and most other mammals. The diaphragmatic vertebra marks the transition in vertebral articular facet (zygapophysis) orientation, which either resists (prediaphragmatic) or allows (postdiaphragmatic) trunk movement in the sagittal plane (i.e., flexion and extension). Unlike most mammals, which have dorsomobile spines (long lumbar columns and cranially placed diaphragmatic vertebrae) for running and leaping, hominoids possess dorsostable spines (short lumbar columns and caudally placed diaphragmatic vertebrae) adapted to orthogrady and antipronogrady. In contrast to humans and other extant hominoids, all known early hominin partial vertebral columns demonstrate cranial displacement of the diaphragmatic vertebra. To address this difference, variation in diaphragmatic placement is assessed in a large sample of catarrhine primates. I show that while hominoids are characterized by modal common placement of diaphragmatic and last rib-bearing vertebrae in general, interspecific differences in intraspecific patterns of variation exist. In particular, humans and chimpanzees show nearly identical patterns of diaphragmatic placement. A scenario of hominin evolution is proposed in which early hominins evolved cranial displacement from the ancestral hominid condition of common placement to achieve effective lumbar lordosis during the evolution of bipedal locomotion.     

Morphological study of the anthropoid thoracic cage: scaling of thoracic width and an analysis of rib curvature

While a relatively broad thorax and strongly curved ribs are widely regarded as common features of living hominoids, few studies have quantitatively examined these traits by methods other than calculating the chest index. The present study aims to quantify variations in thoracic cage morphology for living anthropoids. The odd-numbered ribs (first to eleventh) were articulated with the corresponding vertebrae and the cranial and lateral views subsequently photographed. Rib profiles were digitized in both views and line-fitted by a Bézier curve to create a three-dimensional morphological data set. When thoracic cage width was scaled against body mass, Hylobates (and possibly Pongo) plotted above non-hominoid anthropoids at almost all rib levels, while Pan did not differ from non-hominoid anthropoids. The overall pattern of the normalized thoracic width differed between Hylobates and other hominoids. In Hylobates, an upward convex curve was seen between the first and seventh ribs while a more linear pattern was observed in Pan and Pongo. This result quantitatively confirmed that the barrel-shaped thoracic cage in Hylobates can be distinguished from the funnel-shaped form in other hominoids. Conversely, all hominoids shared two distinct features in the upper half-thorax: (1) a pronounced dorsal protrusion of the proximal part of the rib in accordance with ventral displacement of the thoracic spine and (2) a relatively medially projecting sternal end. Although these features are likely to provide some mechanical advantage in orthograde and/or suspensory positional behaviors, they were barely present in the suspensory Ateles. An erratum to this article can be found at     

Reconciling the convergence of supraspinous fossa shape among hominoids in light of locomotor differences

Differences in scapular morphology between modern humans and the African and lesser apes are associated with the distinct locomotor habits of these groups. However, several traits, particularly aspects of the supraspinous fossa, are convergent between Homo and Pongo—an unexpected result given their divergent locomotor habits. Many morphological assessments of the scapula rely on the limited number of static landmarks available, and traditional approaches like these tend to oversimplify scapular shape. Here, we present the results of two geometric morphometric (GM) analyses of hominoid supraspinous fossa shape—one employing five homologous landmarks and another with 83 sliding semilandmarks—alongside those of traditional methods to evaluate if three-dimensional considerations of fossa shape afford more comprehensive insights into scapular shape and functional morphology. Traditional measures aligned Pongo and Homo with narrow and transversely oriented supraspinous fossae, whereas African ape and Hylobates fossae are broader and more obliquely situated. However, our GM results highlight that much of the convergence between Homo and Pongo is reflective of their more medially positioned superior angles. These approaches offered a more complete assessment of supraspinous shape and revealed that the Homo fossa, with an intermediate superior angle position and moderate superoinferior expansion, is actually reminiscent of the African ape shape. Additionally, both Pongo and Hylobates were shown to have more compressed fossae, something that has not previously been identified through traditional analyses. Thus, the total morphological pattern of the Pongo supraspinous fossa is unique among hominoids, and possibly indicative of its distinctive locomotor habits. Am J Phys Anthropol 156:498–510, 2015. © 2015 Wiley Periodicals, Inc.     

Functional morphology and anatomy of cervical vertebrae in Nacholapithecus kerioi, a middle Miocene hominoid from Kenya

This paper describes the morphology of cervical vertebrae in Nacholapithecus kerioi, a middle Miocene primate species excavated from Nachola, Kenya in 1999-2002. The cervical vertebrae in Nacholapithecus are larger than those of Papio cynocephalus. They are more robust relative to more caudal vertebral bones. Since Nacholapithecus had large forelimbs, it is assumed that strong cervical vertebrae would have been required to resist muscle reaction forces during locomotion. On the other hand, the vertebral foramen of the lower cervical vertebrae in Nacholapithecus is almost the same size as or smaller than that of P. cynocephalus. Atlas specimens of Nacholapithecus resemble those of extant great apes with regard to the superior articular facet, and they have an anterior tubercle trait intermediate between that of extant apes and other primate species. Nacholapithecus has a relatively short and thick dens on the axis, similar to those of extant great apes and the axis body shape is intermediate between that of extant apes and other primates. Moreover, an intermediate trait between extant great apes and other primate species has been indicated with regard to the angle between the prezygapophyseal articular facets of the axis in Nacholapithecus. Although the atlas of Nacholapithecus is inferred as having a primitive morphology (i.e., possessing a lateral bridge), the shape of the atlas and axis leads to speculation that locomotion or posture in Nacholapithecus involved more orthograde behavior similar to that of extant apes, and, in so far as cervical vertebral morphology is concerned, it is thought that Nacholapithecus was incipiently specialized toward the characteristics of extant hominoids.     

Evaluation of "unique" aspects of human vertebral bodies and pedicles with a consideration of Australopithecus africanus

Recent functional studies of human vertebrae have revealed that loads borne by the axial skeleton during bipedal postures and locomotion pass through the pedicles and posterior elements as well as through the bodies and discs. Accordingly, particular morphological attributes of these vertebral elements have been linked exclusively with bipedalism. In order to test the validity of current form-function associations in human vertebral anatomy, this study considers the morphology of human thoracolumbar vertebral bodies and pedicles in the context of a wide comparative primate sample. The last lumbar vertebra of STS 14 (Australopithecus africanus) is also included in the analysis. Results indicate that certain features of human vertebrae previously thought to reflect bipedalism are characteristic of several nonhuman primates, including those whose posture is habitually pronograde. These features include the decrease in vertebral body surface area and the increase in cross-sectional area of the pedicle between the penultimate and last lumbar vertebra. In addition, although humans have relatively large and wide last lumbar pedicles, the enlargement and widening of the pedicle between the penultimate and last lumbar vertebra is not unique to humans. On the other hand, human vertebrae do exhibit several unique adaptations to bipedal posture and locomotion: (1) the vertebral body surface areas of the lower lumbar vertebrae and the cross-sectional areas of the last lumbar pedicles are large relative to body size, and (2) the last lumbar pedicles are wider relative to length and to body size than are those of nonhuman primates. The last lumbar vertebra of STS 14 does not exhibit any of these human-like vertebral features—its pedicles and body surface areas are relatively small, and its pedicles are not relatively wide, but relatively short.     

Morphometric analysis of hominoid lower molars from Yuanmou of Yunnan Province, China

Shape analyses of cross-sectional mandibular molar morphology, using Euclidean Distance Matrix Analysis, were performed on 79 late Miocene hominoid lower molars from Yuanmou of Yunnan Province, China. These molars were compared to samples of chimpanzee, gorilla, orangutan,Lufengpithecus lufengensis, Sivapithecus, Australopithecus afarensis, and human mandibular molars. Our results indicate that the cross-sectional shape of Yuanmou hominoid lower molars is more similar to the great apes that to humans. There are few differences between the Yuanmou,L. lufengensis, andSivapithecus molars in cross-sectional morphology, demonstrating strong affinities between these three late Miocene hominoids. All three of the fossil samples show strong similarities to orangutans. From this, we conclude that these late Miocene hominoids are more closely related to orangutants than to either the African great apes or humans.     

Evolution of the second orangutan: phylogeny and biogeography of hominid origins

Aim To resolve the phylogeny of humans and their fossil relatives (collectively, hominids), orangutans (Pongo) and various Miocene great apes and to present a biogeographical model for their differentiation in space and time. Location Africa, northern Mediterranean, Asia. Methods Maximum parsimony analysis was used to assess phylogenetic relationships among living large‐bodied hominoids (= humans, chimpanzees, bonobos, gorillas, orangutans), and various related African, Asian and European ape fossils. Biogeographical characteristics were analysed for vicariant replacement, main massings and nodes. A geomorphological correlation was identified for a clade we refer to as the ‘dental hominoids’, and this correlation was used to reconstruct their historical geography. Results Our analyses support the following hypotheses: (1) the living large‐bodied hominoids represent a monophyletic group comprising two sister clades: humans + orangutans, and chimpanzees (including bonobos) + gorillas (collectively, the African apes); and (2) the human–orangutan clade (dental hominoids) includes fossil hominids (Homo, australopiths, Orrorin) and the Miocene‐age apes Hispanopithecus, Ouranopithecus, Ankarapithecus, Sivapithecus, Lufengpithecus, Khoratpithecus and Gigantopithecus (also Plio‐Pleistocene of eastern Asia). We also demonstrate that the distributions of living and fossil genera are largely vicariant, with nodes of geographical overlap or proximity between Gigantopithecus and Sivapithecus in Central Asia, and between Pongo, Gigantopithecus, Lufengpithecus and Khoratpithecus in East Asia. The main massing is represented by five genera and eight species in East Asia. The dental hominoid track is spatially correlated with the East African Rift System (EARS) and the Tethys Orogenic Collage (TOC). Main conclusions Humans and orangutans share a common ancestor that excludes the extant African apes. Molecular analyses are compromised by phenetic procedures such as alignment and are probably based on primitive retentions. We infer that the human–orangutan common ancestor had established a widespread distribution by at least 13 Ma. Vicariant differentiation resulted in the ancestors of hominids in East Africa and various primarily Miocene apes distributed between Spain and Southeast Asia (and possibly also parts of East Africa). The geographical disjunction between early hominids and Asian Pongo is attributed to local extinctions between Europe and Central Asia. The EARS and TOC correlations suggest that these geomorphological features mediated establishment of the ancestral range.     

Sphingosine 1-phosphate differentially regulates proliferation of C2C12 reserve cells and myoblasts

Scoliosis is a condition that involves an abnormal curvature and deformity of the spinal vertebrae. The genetic background and key gene for congenital scoliosis in humans are still poorly understood. Ishibashi rats (ISR) have congenital malformation of the lumbar vertebrae leading to kyphoscoliosis similar to that seen in humans. To understand the pathogenesis of congenital scoliosis, we have studied the abnormality of vertebral formation and the associated gene expression in ISR. Almost all ISR showed kyphosis or scoliosis of the lumbar vertebrae. In ISR with severe kyphosis, some vertebral disks were missing and some vertebral bodies were fused. Of the ISR, 27% showed hemi-lumbarization of lumbar and sacral vertebrae. Homeotic transformation of the first sacral vertebra into the seventh lumbar vertebra and the resultant loss of the fourth sacral vertebra were seen in half of the ISR. We also found unilateral fusions and deformities of primary ossification centers of the lumbar vertebral column in fetal ISR. Moreover, we observed that the expression levels of Hox10 and Hox11 paralogs in lumbo-sacral transitional areas of ISR were extremely low compared with those of normal rats. These results suggest that fusion of primary ossification centers in lumbar vertebrae in the embryonic period causes scoliosis and kyphosis and that Hox genes are involved in the occurrence of homeotic transformation in lumbo-sacral vertebrae of congenital kyphoscoliotic ISR.     

伤椎置钉联合短节段内固定与单纯短节段固定治疗胸腰椎爆裂性骨折的比较研究

目的:比较伤椎置钉联合短节段内固定与单纯短节段固定治疗胸腰椎爆裂性骨折的临床疗效、固定效果及其对患者炎症反应和脊髓损伤的影响。方法:选取2014年3月到2016年12月期间我院收治的胸腰椎爆裂性骨折患者94例,根据手术方法的不同将患者分为伤椎置钉组(40例)和短节段内固定组(44例)。短节段内固定组患者采用单纯后路短节段椎弓根螺钉内固定进行治疗,伤椎置钉组采用伤椎置钉联合后路短节段椎弓根螺钉内固定进行治疗。比较两组患者的手术时间、术中出血量、住院时间、伤椎前沿高度比、Cobb’s角、伤椎椎体楔形变角、视觉模拟评分(VAS)和Oswestry功能障碍指数(ODI),炎性因子指标、脊髓损伤指标及术后并发症。结果:伤椎置钉组的手术时间长于短节段内固定组(P<0.05),术后6个月、术后12个月伤椎置钉组的伤椎前沿高度比明显高于短节段内固定组,Cobb’s角、伤椎椎体楔形变角明显低于短节段内固定组(P<0.05),术前、术后1周、术后6个月、术后12个月两组患者的VAS评分和ODI比较差异无统计学意义(P>0.05),术后3 d两组患者血清中IL-1β、IL-6、IL-8、TNF-α和pNF-H、NSE、S100β、GFAP水平比较差异均无统计学意义(P>0.05)。随访期间两组患者均未出现严重并发症。结论:伤椎置钉联合后路短节段椎弓根螺钉内固定可有效改善胸腰椎爆裂性骨折患者的椎体高度、Cobb’s角和伤椎椎体楔形变角,并且不会增加脊髓损伤和机体的炎症反应。     

Body weight prediction in early fossil hominids: Towards a taxon-“independent” approach

The choice of a model taxon is crucial when investigating fossil hominids that clearly do not resemble any extant species (such as Australopithecus) or show significant differences from modern human proportions (such as Homo habilis OH 62). An “interhominoid” combination is not adequate either, as scaling with body weight is strongly divergent in African apes and humans for most skeletal predictors investigated here. Therefore, in relation to a study of seven long bone dimensions, a new taxon-“independent” approach is suggested. For a given predictor, its taxonomic “independence” is restricted to the size range over which the body weight-predictor relationship for African apes and humans converges. Different predictors produce converging body weight estimates (BWEs) for different size ranges: taxon-“independent” estimates can be calculated for small- and medium-sized hominids (e. g., for weights below 50 kg) using femoral and tibial dimensions, whereas upper limb bones provide converging results for large hominids (above 50 kg). If the remains of Australopithecus afarensis really belong to one species, the relationship of male (above 60 kg) to female body weight (approximately 30 kg) does not fall within the observed range of modern hominoids. Considering Sts 14 (22 kg) to represent a small-sized Australopithecus africanus, the level of encephalization lies well above that of extant apes. If OH 62 (approximately 25 kg), with limb proportions less human-like than those of australopithecines, indeed represents Homo habilis (which has been questioned previously), an increase in relative brain size would have occurred well before full bipedality, an assumption running counter to current assumptions concerning early human evolution. © 1993 Wiley-Liss, 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.     

Validation of single-segment and three-segment spinal models used to represent lumbar flexion

Changes in spinal posture between the erect and flexed positions were calculated using angular measurements from lateral photographs and radiographs of ten adult male subjects. For photographic measurements, the thoracolumbar vertebral column was modelled as either a single segment or as three segments. In the three-segment model, there was a non-significant correlation between the decrease in lumbar concavity and intervertebral motion. In addition, there was a non-significant negative correlation between the increase in thoracic convexity and lumbar motion determined radiographically. In the single-segment model, the decrease in angulation between the thoracolumbar spine and pelvis was a good representation of lumbar spine flexion as determined by the mean lumbar intervertebral angular change. Therefore, modelling the thoracolumbar vertebral column as a single segment allowed better estimation of lumbar intervertebral angular change during flexion than a three-segment model. The results indicate that large range dynamic motion of the lumbar vertebral column can be represented using photographic analysis of the positions of three easily identified anatomical landmarks: the anterior superior iliac spine, posterior superior iliac spine and the spinous process of the first thoracic vertebra.