Head posture in the Hominoidea

The angle between the antero-posterior plane of the occipital condyles and a vertical axis at right angles to the Frankfort Horizontal was measured in Homo sapiens, Gorilla, Pan, Pongo and casts of two Neanderthal skulls, the Rhodesian skull and three australopithecine skulls. The angle was much greater in adult Homo sapiens and in the Neanderthal and australopithecine casts than in the adult groups of the three apes. In the immature groups, the angle underwent little change with age in Homo sapiens but in Gorilla and Pan the angle decreased markedly during the growth period. These findings can be readily correlated with the habitual bodily posture of each of the extant genera. In Homo sapiens , an upright posture is adopted early in life while in the African apes the young tend to move by brachiation and thus have an habitual posture of the spine closer to the vertical than in the "knuckle walking" adults. The large value of the angle in the Neanderthal casts also correlates well with the now widely held view that this group has a fully upright posture. However, the finding of a relatively low value for the angle in adult Pongo —a brachiator—runs counter to the general thesis that the angle is a direct reflection of overall posture and casts some doubt upon a conclusion that the large value of the angle in the australopithecine fossils necessarily indicates that these creatures stood upright.     

禄丰古猿前部牙齿的釉面横纹与牙冠形成时间

釉面横纹的数目可用于推断个体牙齿的牙冠形成时间,在生长发育研究中具有重要的意义。本研究运用数码体视显微镜和扫描电镜观察了云南石灰坝禄丰禄丰古猿(简称禄丰古猿)30枚齿冠完整的前部牙齿,包括上下颌中门齿6枚、侧门齿10枚和犬齿14枚。根据唇侧面釉面横纹计数的观察结果,分别以7天和9天芮氏线生长周期,估算各齿型的牙冠形成时间,结果显示:以生长周期7天计算,中门齿牙冠形成时间约为3.6-4.1年,侧门齿牙冠形成时间约为2.7-3.7年,犬齿牙冠形成时间约为4.2-7.0;以生长周期9天计算,中门齿牙冠形成时间约为4.4-5.2年,侧门齿牙冠形成时间约为3.4-4.7年,犬齿牙冠形成时间约为5.2-8.8年。为更深入地了解禄丰古猿牙冠形成时间在不同齿型及性别间足否存在明显差异,本文用SPSS软件对其进行显著性差异检验。采用小样本平均值的t值假设检验(置信区间为95%),结果如下:禄丰古猿前部牙齿的牙冠形成时间在各类牙齿的上下颌中不存在显著性差异;犬齿牙冠形成时间存在非常显著的性别差异,雄性牙冠形成时间明显长于雌性,侧门齿也存在显著的性别差异,而中门齿性别间则无显著性差异。此外对禄丰古猿中门齿,侧门齿和犬齿的牙冠形成时间进行单因素方差分析并两两对比,结果显示中门齿与侧门齿的牙冠形成时间不存在显著性差异,而犬齿与中门齿和侧门齿均存在显著性差异,犬齿牙冠形成时间明显长于门齿。同时也对禄丰古猿前部牙齿的牙冠形成时间与齿冠高进行相关性分析,其结果表明两者有显著的正相关性。将禄丰古猿与其他古猿和现生大猿、南方古猿以及人属成员进行对比,结果显示其前部牙齿牙冠形成时间长于原修康尔猿、南方古猿、傍人、人属成员,接近于蝴蝶禄丰古猿和大猩猩,而明显小于黑猩猩、华南化石猩猩及现生猩猩。     

A 3D quantitative comparison of trapezium and trapezoid relative articular and nonarticular surface areas in modern humans and great apes

The structure and functions of the modern human hand are critical components of what distinguishes Homo sapiens from the great apes (Gorilla, Pan, and Pongo). In this study, attention is focused on the trapezium and trapezoid, the two most lateral bones of the distal carpal row, in the four extant hominid genera, representing the first time they have been quantified and analyzed together as a morphological-functional complex. Our objective is to quantify the relative articular and nonarticular surface areas of these two bones and to test whether modern humans exhibit significant shape differences from the great apes, as predicted by previous qualitative analyses and the functional demands of differing manipulative and locomotor strategies. Modern humans were predicted to show larger relative first metacarpal and scaphoid surfaces on the trapezium because of the regular recruitment of the thumb during manipulative behaviors; alternatively, great apes were predicted to show larger relative second metacarpal and scaphoid surfaces on the trapezoid because of the functional demands on the hands during locomotor behaviors. Modern humans were also expected to exhibit larger relative mutual joint surfaces between the trapezoid and adjacent carpals than do the great apes because of assumed transverse loads generated by the functional demands of the modern human power grip. Using 3D bone models acquired through laser digitizing, the relative articular and nonarticular areas on each bone are quantified and compared. Multivariate analyses of these data clearly distinguish modern humans from the great apes. In total, the observed differences between modern humans and the great apes support morphological predictions based on the fact that this region of the human wrist is no longer involved in weight-bearing during locomotor behavior and is instead recruited solely for manipulative behaviors. The results provide the beginnings of a 3D comparative standard against which further extant and fossil primate wrist bones can be compared within the contexts of manipulative and locomotor behaviors.     

Phylogeny, neoteny and growth of the cranial base in hominoids

This study tests the hypothesis that there is a general pattern in the growth of the cranial base of Homo sapiens that is 'essentially neotenous' [Gould, 1977]. Juvenile and adult crania of Homo sapiens, Gorilla gorilla, Pan troglodytes and Pongo pygmaeus were studied and the cross-sectional growth curves for 10 measurements made on the cranial base (as viewed in norma basilaris) were compared. The results of this study suggest that relatively simple modifications to the timing or pattern of growth are insufficient to explain the observed morphological differences between the cranial base of modern Homo sapiens and the great apes.     

Comparison of cranial ontogenetic trajectories among great apes and humans

Molecular data suggest that humans are more closely related to chimpanzees than either is to the gorillas, yet one finds the closest similarity in craniofacial morphology to be among the great apes to the exclusion of humans. To clarify how and when these differences arise in ontogeny, we studied ontogenetic trajectories for Homo sapiens, Pan paniscus, Pan troglodytes, Gorilla gorilla and Pongo pygmaeus. A total of 96 traditional three-dimensional landmarks and semilandmarks on the face and cranial base were collected on 268 adult and sub-adult crania for a geometric morphometric analysis. The ontogenetic trajectories are compared by various techniques, including a new method, relative warps in size-shape space. We find that adult Homo sapiens specimens are clearly separated from the great apes in shape space and size-shape space. Around birth, Homo sapiens infants are already markedly different from the great apes, which overlap at this age but diverge among themselves postnatally. The results suggest that the small genetic differences between Homo and Pan affect early human ontogeny to induce the distinct adult human craniofacial morphology. Pure heterochrony does not sufficiently explain the human craniofacial morphology nor the differences among the African apes.     

Brief Communication: Shape analysis of the MT 1 proximal articular surface in fossil hominins and shod and unshod Homo

As a follow-up study to Proctor et al. (Am J Phys Anthropol 135 (2008) 216-224), this study quantifies the first metatarsal proximal articular surface using three-dimensional morphometrics to test for differences in articular surface shape between habitually shod and habitually unshod humans. In addition, differences in shape between Homo, Pan, Gorilla, and Hylobates are compared to the fossil hominin specimens A. L. 333-54, Stw 562, Stw 573 ("Little Foot"), OH 8, SKX 5017, and SK 1813. No difference in surface shape was found between habitually shod and habitually unshod humans. There is a clear quantitative division in articular surface shape between humans and apes that is more pronounced than a previous study by Proctor et al. (Am J Phys Anthropol 135 (2008) 216-224), due to additional landmarks present in this study. The specimen OH 8 is indistinguishable from modern Homo. The fossils A. L. 333-54, Stw 562, and Stw 573 are intermediate in shape between humans and apes. The specimens SKX 5017 and SK 1813 have a more apelike articular surface. When combined with other characteristics, this trait suggests that Paranthropus used a degree of abduction during locomotion that was much less than that in extant apes, but greater than that in Australopithecus, allowing for some small degree of grasping ability.     

Comparative myology of the hominoid cranial base. I. The muscular relationships and bony attachments of the digastric muscle

This paper aims to document accurately the soft tissue anatomy and bony attachments of the posterior belly of the digastric muscle and other closely related muscles in the mastoid region of extant hominoids and fossil hominids. Five wet specimens including individuals of Pan, Gorilla and Pongo were dissected and described. Eight casts of fossil hominid cranial bases were also studied along with measurements and notes made from the same original fossil hominid specimens to assess their soft tissue markings in the light of the findings for the three great apes. The results indicate that whereas the attachment of the posterior belly of the digastric muscle in Homo sapiens is associated with a deep groove or fossa, it originates from a widened area and leaves no bony markings on the cranial base of the three great apes. Following a change in the position of the foramen magnum and the occipital condyles in hominids and H. sapiens the insertion of the posterior belly of the digastric has remained posteriorly positioned but has become compressed into a deep groove. It is likely that this has come about by the displacement of the more medial soft tissue structures which have been moved laterally away from the occipital condyles.     

Quantitative three-dimensional shape analysis of the proximal hallucial metatarsal articular surface in Homo, Pan, Gorilla, and Hylobates

Multidimensional morphometrics is used to compare the proximal articular surface of the first metatarsal between Homo, Pan, Gorilla, Hylobates, and the hominin fossils A.L. 333-54 (A. afarensis), SKX 5017 (P. robustus), and OH 8 (H. habilis). Statistically significant differences in articular surface morphology exist between H. sapiens and the apes, and between ape groups. Ape groups are characterized by greater surface depth, an obliquely curved articular surface through the dorso-lateral and medio-plantar regions, and a wider medio-lateral surface relative to the dorso-plantar height. The OH 8 articular surface is indistinguishable from H. sapiens, while A.L. 333-54 and SKX 5017 more closely resemble the apes. P. robustus and A. afarensis exhibit ape-like oblique curvature of the articular surface.     

The deciduous lower dentition of Ouranopithecus macedoniensis (Primates, Hominoidea) from the late Miocene deposits of Macedonia, Greece

Two mandibular fragments with associated milk teeth assigned to the late Miocene hominoid primate Ouranopithecus macedoniensis are analyzed. The fossils, which belong to a single individual, were found in the Vallesian locality of "Ravin de la Pluie" of the Axios Valley (Macedonia, Greece). The material is described here and compared with extant and extinct hominoids, allowing assessment of the evolutionary trends in the deciduous lower dentition within the Hominoidea. Hylobatids represent the more primitive pattern. Gorilla is slightly more derived than hylobatids, but less derived than Pongo and Pan, the latter being the most derived. With relatively smaller deciduous canines and more molarized deciduous premolars, Ouranopithecus is more derived than both Pan and Gorilla. Among the fossil hominoids, Proconsul, representing the primitive condition, has a very simple dp(3)and a dp(4)that has a trigonid that is taller than the talonid and which lacks a hypoconulid. Griphopithecus is more derived than Proconsul in having a dp(4) with a lower trigonid, a hypoconulid, and a less oblique cristid obliqua. Australopithecus and Paranthropus possess a similar morphology to that of Homo, while Ardipithecus appears to be more primitive than the latter genera. Ouranopithecus has a more derived lower milk dentition than Proconsul and Griphopithecus, but less derived than Australopithecus and Paranthropus. The comparison of the lower milk dentition of Ouranopithecus confirms our previous conclusions suggesting that this fossil hominoid shares derived characters with Australopithecus and Homo.     

Early hominin limb proportions

Recent analyses and new fossil discoveries suggest that the evolution of hominin limb length proportions is complex, with evolutionary reversals and a decoupling of proportions within and between limbs. This study takes into account intraspecific variation to test whether or not the limb proportions of four early hominin associated skeletons (AL 288-1, OH 62, BOU-VP-12/1, and KNM-WT 15000) can be considered to be significantly different from one another. Exact randomization methods were used to compare the differences between pairs of fossil skeletons to the differences observed between all possible pairs of individuals within large samples of Gorilla gorilla, Pan troglodytes, Pongo pygmaeus, and Homo sapiens. Although the difference in humerofemoral proportions between OH 62 and AL 288-1 does not exceed variation in the extant samples, it is rare. When humerofemoral midshaft circumferences are compared, the difference between OH 62 and AL 288-1 is fairly common in extant species. This, in combination with error associated with the limb lengths estimates, suggests that it may be premature to consider H. (or Australopithecus) habilis as having more apelike limb proportions than those in A. afarensis. The humerofemoral index of BOU-VP-12/1 differs significantly from both OH 62 and AL 288-1, but not from KNM-WT 15000. Published length estimates, if correct, suggest that the relative forearm length of BOU-VP-12/1 is unique among hominins, exceeding those of the African apes and resembling the proportions in Pongo.Evidence that A. afarensis exhibited a less apelike upper:lower limb design than A. africanus (and possibly H. habilis) suggests that, if A. afarensis is broadly ancestral to A. africanus, the latter did not simply inherit primitive morphology associated with arboreality, but is derived in this regard. The fact that the limb proportions of OH 62 (and possibly KNM-ER 3735) are no more human like than those of AL 288-1 underscores the primitive body design of H. habilis.     

Variations of the mandibular shape in extant hominoids: Generic, specific, and subspecific quantification using elliptical fourier analysis in lateral view

While a number of studies have documented the mandibular variations in hominoids, few focused on evaluating the variation of the whole outline of this structure. Using an efficient morphometrical approach, i.e. elliptical Fourier analysis, mandibular outlines in lateral view from 578 adult hominoids representing the genera Hylobates, Pongo, Gorilla, Pan, and Homo were quantified and compared. This study confirms that elliptical Fourier analysis provides an accurate characterization of the shape of the mandibular profile. Differences in mandibular shape between hominoid genera, species, subspecies, and to a lesser extent between sexes were demonstrated. Mandibles in great apes and hylobatids subspecies were generally less distinct from each other than were species. However, the magnitudes of differences among subspecies of Gorilla and Pongo approached or exceeded those between Pan troglodytes and P. paniscus. The powerful discrimination between taxa from the genus down to subspecific level associated to the relatively low level of intrageneric mandibular polymorphism in great apes provides strong evidences in support of the taxonomic utility of the shape of the mandibular profile in hominoids. In addition, morphological affinities between Pongo and Pan and the clear distinction between Homo and Pan suggest that the mandibular outline is a poor estimate of phylogenetic relationships in great apes and humans. The sexual dimorphism in mandibular shape exhibits two patterns of expression: a high degree of dimorphism in Gorilla, Pongo, and H. s. syndactylus and a relatively low one in modern humans and Pan. Besides, degree of mandibular shape dimorphism can vary considerably among closely related subspecies as observed in gorillas, arguing against the use of mandibular shape dimorphism patterns as characters in phylogenetic analyses. However, the quantification of the mandibular shape and of the variations among hominoids provides an interesting comparative framework that is likely to supply further arguments for a better understanding of the patterns of differentiation between living hominoids.     

Size and shape dimorphism in great ape mandibles and implications for fossil species recognition

Sexual dimorphism is an important source of morphological variation, and species differences in dimorphism may be reflected in magnitude, pattern, or both. While the extant great apes are commonly used as a reference sample for distinguishing between sexual dimorphism and intertaxic variation in the fossil record, few studies have evaluated mandibular dimorphism in these taxa. In this study, percentage, degree, and pattern of mandibular dimorphism are evaluated in Pongo, Gorilla, and Pan. Mandibular dimorphism patterns are explored to determine the extent to which such patterns accurately track great ape phylogeny. Pattern stability is assessed to determine whether there are stable patterns of mandibular size and shape dimorphism that may be usefully applied to hominoid or hominid fossil species recognition studies. Finally, the established patterns of dimorphism are used to address recent debates surrounding great ape taxonomy. Results demonstrate that mandibular dimorphism is universally expressed in size, but only Pongo and Gorilla exhibit shape dimorphism. Pattern similarity tends to be greater between subspecies of the same species than between higher-order taxa, suggesting that within the great apes, there is a relationship between dimorphism pattern and phylogeny. However, this relationship is not exact, given that dimorphism patterns are weakly correlated between some closely related taxa, while great ape subspecies may be highly correlated with taxa belonging to other species or genera. Furthermore, dimorphism patterns are not significantly correlated between great ape genera, even between Gorilla and Pan. Dimorphism patterns are more stable in Gorilla and Pongo as compared to Pan, but there is little pattern stability between species or genera. Importantly, few variables differ significantly between taxa that simultaneously show consistently relatively low levels of dimorphism and low levels of variation within taxa. Combined, these findings indicate that mandibular dimorphism patterns can and do vary considerably, even among closely related species, and suggest that it would be difficult to employ great ape mandibular dimorphism patterns for purposes of distinguishing between intra- and interspecies variation in fossil samples. Finally, the degree of pattern similarity in mandibular dimorphism is lower than previously observed by others for craniofacial dimorphism. Thus, the possibility cannot be ruled out that patterns of craniofacial dimorphism in great apes may be associated with a stronger phylogenetic signal than are patterns of mandibular dimorphism.     

Ontogeny and phylogeny of the pelvis in Gorilla, Pongo, Pan, Australopithecus and Homo

To examine the evolutionary differences between hominoid locomotor systems, a number of observations concerning the growth of the pelvis among the great apes as compared to modern and fossil hominids are reported. We are interested in the size and shape of the coxal bones at different developmental stages across species that may elucidate the relationship between ontogeny and phylogeny (i.e., heterochrony) in the hominoid pelvis. Our hypotheses are: (1) do rates of absolute growth differ?, (2) do rates of relative growth differ?, and (3) does heterochrony explain these differences? Bivariate and multivariate analyses of pelvic dimensions demonstrate both the diversity of species-specific ontogenetic patterns among hominoids, and an unequivocal separation of hominids and the great apes. Heterochrony alone fails to account for the ontogenetic differences between hominids and the great apes. Compared to recent Homo,Australopithecus can be described as 'hyper-human' from the relative size of the ischium, and short but broad ilium. Australopithecus afarensis differs from Australopithecus africanus by its relatively long pubis. In multivariate analyses of ilium shape, the most complete coxal bone attributed to Homo erectus, KNM-ER 3228, falls within the range of juvenile and adult Australopithecus, whereas Broken Hill falls within the range of modern Homo, suggesting that the modern human ilium shape arose rather recently. Among the great apes, patterns of pelvic ontogeny do not exclusively separate the African apes from Pongo.     

Preliminary observations on increasing root length during the eruptive phase of tooth development in modern humans and great apes

Ground sections of incisors, canines, and molars were selected that showed clear incremental markings in root dentine. The sample comprised 98 Homo sapiens, 53 Pan troglodytes, and a more limited combined sample of 51 Gorilla and Pongo sections. Daily rates of root dentine formation, together with the orientation of incremental markings in roots close to the cement-dentine junction (CDJ), were used to calculate root extension rates for the first 10mm of root formed beyond the buccal enamel cervix. Modern human anterior tooth roots showed a more regular pattern of increase in root length than those in great apes. In Pan, root growth rose quickly to higher rates but then flattened off. The fastest extension rates in modern humans were in incisor roots (10-12 microm per day), followed by canines (8-9 microm per day). Extension rates in Pan rose to slightly greater values in canines ( approximately 12-14 microm per day) than in incisors ( approximately 10-11 microm per day). Molar tooth roots in both modern humans and great apes grew in a nonlinear manner. Peak rates in molars reduced from M1 to M3 (8, 7, and 6 microm per day, respectively). Like humans, root growth in Pan peaked earlier in M1s at rates of between 8 and 9 microm per day, and later in M3s at rates of 7 to 8 microm per day. The more limited data set for Gorilla and Pongo molars suggests that extension rates were generally higher than in Pan by approximately 1.0-1.5 microm per day. There were greater differences in peak extension rates, with Gorilla and Pongo extension rates being between 2.5 and 4.5 microm per day higher than those in Pan. These findings highlight for the first time that root growth rates differ between tooth types in both pattern and rate and between taxa. They provide the basis with which to explore further the potential comparative relationships between root growth, jaw growth, and the eruption process.     

Articular morphology of the proximal ulna in extant and fossil hominoids and hominins

Extant hominoids share similar elbow joint morphology, which is believed to be an adaptation for elbow stability through a wide range of pronation-supination and flexion-extension postures. Mild variations in elbow joint morphology reported among extant hominoids are often qualitative, where orangutans are described as having keeled joints, and humans and gorillas as having flatter joints. Although these differences in keeling are often linked to variation in upper limb use or loading, they have not been specifically quantified. Many of the muscles important in arboreal locomotion in hominoids (i.e., wrist and finger flexors and extensors) take their origins from the humeral epicondyles. Contractions of these muscles generate transverse forces across the elbow, which are resisted mainly by the keel of the humeroulnar joint. Therefore, species with well-developed forearm musculature, like arboreal hominoids, should have more elbow joint keeling than nonarboreal species. This paper explores the three- and two-dimensional morphology of the trochlear notch of the elbow of extant hominoids and fossil hominins and hominoids for which the locomotor habitus is still debated. As expected, the elbow articulation of habitually arboreal extant apes is more keeled than that of humans. In addition, extant knuckle-walkers are characterized by joints that are distally expanded in order to provide greater articular surface area perpendicular to the large loads incurred during terrestrial locomotion with an extended forearm. Oreopithecus is characterized by a pronounced keel of the trochlear notch and resembles Pongo and Pan. OH 36 has a morphology that is unlike that of extant species or other fossil hominins. All other hominin fossils included in this study have trochlear notches intermediate in form between Homo and Gorilla or Pan, suggesting a muscularity that is less than in African apes but greater than in humans.     

华南化石猩猩前部牙齿釉面横纹与牙冠形成时间研究

釉面横纹的分布与数目可以反映牙齿生长发育的时间和速率变化, 在化石研究中能为复原个体生活史提供重要依据。本研究运用扫描电子显微镜观察华南化石猩猩门齿、犬齿釉面横纹分布与数目, 并估算门齿和犬齿牙冠形成时间, 结果如下: 牙冠从牙尖至牙颈方向釉面横纹分布密度有疏密变化, 牙尖釉面横纹密度小于10条/mm, 中间至牙颈釉面横纹密度较尖部增大, 大约10-15条/mm; 犬齿釉面横纹数目多于门齿, 雄性犬齿釉面横纹数目多于雌性; 根据釉面横纹计数及其生长周期的组织切片观察结果, 估算门齿牙冠形成时间大约为2.97-6.66年, 犬齿雄性长于雌性, 分别为6.25-11.31年和4.28-7.29年。与一些古猿、早期人类、现代人以及现生大猿比较, 华南化石猩猩釉面横纹整体密度稍大于南方古猿和傍人, 小于黑猩猩、大猩猩、现代人和禄丰古猿; 除侧门齿外, 华南化石猩猩釉面横纹数目明显多于南方古猿、傍人和现代人, 与大猩猩接近; 华南猩猩前部牙齿牙冠形成时间与现生大猿、禄丰古猿差别不大, 与现生猩猩最相近, 长于南方古猿和傍人。     

Patterns of tooth crown size and shape variation in great apes and humans and species recognition in the hominid fossil record

It has been suggested that patterns of craniodental variation in living hominids (Gorilla, Homo, Pan, and Pongo) may be useful for evaluating variation in fossil hominid assemblages. Using this approach, a fossil sample exhibiting a pattern of variation that deviates from one shared among living taxa would be regarded as taxonomically heterogeneous. Here we examine patterns of tooth crown size and shape variation in great apes and humans to determine 1) if these taxa share a pattern of dental variation, and 2) if such a pattern can reliably discriminate between samples that contain single species and those that contain multiple species. We use parametric and nonparametric correlation methods to establish the degree of pattern similarity among taxa, and randomization tests to assess their statistical significance. The results of this study show that extant hominids do not share a pattern of dental size variation, and thus these taxa cannot be used to generate expectations for patterns of size variation in fossil hominid species. The hominines (Gorilla, Homo, and Pan) do share a pattern of shape variation in the mandibular dentition; however, Pongo is distinct, and thus it is unclear which, if either, pattern should be expected in fossil hominids. Moreover, in this case, most combined-species samples exhibit patterns of shape variation that are similar to those for single hominine species samples. Thus, although a common pattern of shape variation is present in the mandibular dentition, it is not useful for recognizing taxonomically mixed paleontological samples.     

Palatine fenestrae,the orangutan and hominoid evolution

Although most mammals develop relatively large double anterior palatine fenestrae that patently communicate with the nasal cavity, four extant primates—Homo sapiens, Pongo, Pan andGorilla—do not. While these four have closed-down these foramenal structures,Homo sapiens andPongo are unique in forming a single foramen palatally. Among fossil taxa,Homo, Australopithecus, Sivapithecus (=Ramapithecus) andRudapithecus also develop a single foramen palatally. Dryopithecines, the presumed fossil apes, preserve the two patent fenestrae. In light of dental features that are considered diagnostically “hominid,” which are also found in the orangutan, it is suggested that this “ape,” rather thanPan, is phylogenetically closer toHomo.     

A fossil hominoid proximal femur from Kikorongo Crater, southwestern Uganda

The external morphology of a fragmentary right proximal femur from southwestern Uganda is described here. Discovered in the Kikorongo Crater of Queen Elizabeth National Park in 1961, this specimen was informally assigned to Homo sapiens (although never described) and tentatively dated to the late Pleistocene. However, because aspects of the external morphology of the femur align the fossil with the African great apes, we suggest that the Kikorongo femur may be the first postcranial fossil of the genus Pan. Like the African apes, the Kikorongo specimen lacks both an obturator externus groove and an intertrochanteric line. It has a short femoral neck with a circular cross section, and a narrow and deep superior notch. Using resampling statistics and discriminant function analysis, the Kikorongo femur clustered with the genus Pan, as opposed to Gorilla or Homo. However, if the specimen is from Pan, it would be large for this taxon. Furthermore, features that clearly distinguish the external morphology of Plio-Pleistocene hominin proximal femora from African ape femora, such as the shape of the femoral neck in cross section and femoral neck length, have converged in Holocene humans and African apes. Unfortunately, the internal morphology of the femoral neck of the Kikorongo fossil was not discernable. Although we hypothesize that the Kikorongo femur is from the genus Pan, there is such variability in the proximal femora of modern humans that, although it would be an unusual human, it remains possible that this fossil represents H. sapiens.     

Postnatal temporal bone ontogeny in Pan,Gorilla, and Homo,and the implications for temporal bone ontogeny in Australopithecus afarensis

Assessments of temporal bone morphology have played an important role in taxonomic and phylogenetic evaluations of fossil taxa, and recent three‐dimensional analyses of this region have supported the utility of the temporal bone for testing taxonomic and phylogenetic hypotheses. But while clinical analyses have examined aspects of temporal bone ontogeny in humans, the ontogeny of the temporal bone in non‐human taxa is less well documented. This study examines ontogenetic allometry of the temporal bone in order to address several research questions related to the pattern and trajectory of temporal bone shape change during ontogeny in the African apes and humans. We further apply these data to a preliminary analysis of temporal bone ontogeny in Australopithecus afarensis. Three‐dimensional landmarks were digitized on an ontogenetic series of specimens of Homo sapiens, Pan troglodytes, Pan paniscus, and Gorilla gorilla. Data were analyzed using geometric morphometric methods, and shape changes throughout ontogeny in relation to size were compared. Results of these analyses indicate that, despite broadly similar patterns, African apes and humans show marked differences in development of the mandibular fossa and tympanic portions of the temporal bone. These findings indicate divergent, rather than parallel, postnatal ontogenetic allometric trajectories for temporal bone shape in these taxa. The pattern of temporal bone shape change with size exhibited by A. afarensis showed some affinities to that of humans, but was most similar to extant African apes, particularly Gorilla. Am J Phys Anthropol 151:630–642, 2013. © 2013 Wiley Periodicals, Inc.