A distal tibia, YGSP 1656, from the early Late Miocene portion of the Chinji Formation in Pakistan is described. The fossil is 11.4 million years old and is one of only six postcranial elements now ...assigned to
Sivapithecus indicus. Aspects of the articular surface are cercopithecoid-like, suggesting some pronograde locomotor activities. However, YGSP 1656 possesses an anteroposteriorly compressed metaphysis and a mediolaterally thick medial malleolus, ape-like features functionally related to orthograde body postures and vertical climbing. YGSP 1656 lacks specializations found in the ankle of terrestrial cercopithecoids and thus
Sivapithecus may have been primarily arboreal. Nevertheless, the morphology of this tibia is unique, consistent with other interpretations of
Sivapithecus postcranial functional morphology that suggest the locomotion of this ape lacks a modern analog. Based on the limited postcranial remains from
S. indicus, we hypothesize that this taxon exhibited substantial body size dimorphism.
Objectives
We describe a novel pelvic feature, the “ventral sulcus,” located on the pubic bone ventrolateral to the pubic symphysis, which is present in A.L. 288‐1 (Australopithecus afarensis) and ...MH2 (Australopithecus sediba). We determine how widespread the appearance of the ventral sulcus is in fossil hominins, modern humans, and other extant hominoids.
Materials and Methods
We examine all known hominin fossils that preserve the medial portion of the pubic bone, including A.L. 288‐1 and MH2. We also study 217 humans derived from global osteological collections and all genera of extant apes.
Results
We illustrate, describe, and define the ventral sulcus and distinguish it from age‐ and sex‐related morphologies that are sometimes present in extant humans. We do not find evidence for the ventral sulcus in our comparative human and ape samples, but find equivocal evidence for its presence in the fossils Sts 14 (Australopithecus africanus) and StW 573 (A. africanus/Australopithecus prometheus).
Discussion
Ventral sulci are potentially present in all four known adult Australopithecus fossils that preserve the medial portion of the pubic bone, but not present in MH1, a subadult Australopithecus sediba. This raises questions about whether ventral sulci are widespread in Australopithecus, confined to adults, or, as A.L. 288‐1, MH2, StW 573, and Sts 14 have all been estimated as female, whether it is a sex‐associated trait. Alternatively, ventral sulci could be taphonomic artifacts or idiosyncratic pathologies. Further research is needed to determine if ventral sulci are functional in origin and how widespread they are in the genus Australopithecus.
The fossilized pubic bones of two adult members of the genus Australopithecus, Australopithecus afarensis (the top images in (a), (b), and (c)) and Australopithecus sediba (the bottom images in (a), (b), and (c)).
The Olduvai Hominid 8 foot: Adult or subadult? DeSilva, Jeremy M.; Zipfel, Bernhard; Van Arsdale, Adam P. ...
Journal of human evolution,
05/2010, Letnik:
58, Številka:
5
Journal Article
Recenzirano
Olduvai Hominid 8 (OH 8), an articulating set of fossil hominin tarsal and metatarsal bones, is critical to interpretations of the evolution of hominin pedal morphology and bipedal locomotion. It has ...been suggested that OH 8 may represent the foot of a subadult and may be associated with the OH 7 mandible, the type specimen of
Homo habilis. This assertion is based on the presence of what may be unfused distal metatarsal epiphyses. Accurately assessing the skeletal maturity of the OH 8 foot is important for interpretations of the functional morphology and locomotor behavior of Plio-Pleistocene hominins. In this study, we compare metatarsal fusion patterns and internal bone morphology of the lateral metatarsals among subadult hominines (85 modern humans, 48
Pan, and 25
Gorilla) to assess the likelihood that OH 8 belonged to either an adult or subadult hominin. Our results suggest that if OH 8 is indeed from a subadult, then it displays a metatarsal developmental pattern that is unobserved in our comparative sample. In OH 8, the fully fused base of the first metatarsal and the presence of trabecular bone at the distal ends of the second and third metatarsal shafts make it highly improbable that it belonged to a subadult, let alone a subadult that matches the developmental age of the OH 7 mandible. In total, the results of this study suggest that the OH 8 foot most likely belonged to an adult hominin.
The “negrito” and African “pygmy” phenotypes are predominately exhibited by hunter-gatherers living in rainforest habitats. Foraging within such habitats is associated with a unique set of locomotor ...behaviors, most notably habitual vertical climbing during the pursuit of honey, fruit, and game. When performed frequently, this behavior is expected to correlate with developmentally plastic skeletal morphologies that respond to mechanical loading. Using six measurements in the distal tibia and talus that discriminate nonhuman primates by vertical climbing frequency, we tested the prediction that intraspecific variation in this behavior is reflected in the morphology of the ankle joint of habitually climbing human populations. First, to explore the plasticity of climbing-linked morphologies, we made comparisons between chimpanzees, gorillas, and orangutans from wild and captive settings. The analysis revealed significant differences in two climbing-linked traits (anterior expansion of the articular surface of the distal tibia and increased degree of talar wedging), indicating that these traits are sensitive to climbing behavior. However, our analyses did not reveal any signatures of climbing behavior in the ankles of habitually climbing hunter-gatherers. These results suggest that the detection of fine-grained differences in human locomotor behaviors at the ankle joint, particularly those associated with arboreality, may be obscured by the functional demands of terrestrial bipedalism. Accordingly, it may be difficult to use population-level characteristics of ankle morphology to make inferences about the climbing behavior of hominins in the fossil record, even when facultative arborealism is associated with key fitness benefits.
Walking and foot arch structure have risk-increasing effects that contribute to decreased physical activity in adults with overweight and obese body mass index (BMI) scores. However, it is unknown ...whether both excessive weight and arch height influence walking compared to the effects of excessive weight or arch height alone. The purpose of this study was to investigate if arch height mediates obesity-related walking characteristics among adults with different BMI classifications. Spatiotemporal walking kinematics and dynamic plantar pressure were collected as adults with normal ( n = 30 ) , overweight ( n = 34 ) , and obese ( n = 25 ) BMI scores walked at their preferred speed. Digital footprints created with plantar pressure data were used to calculate a measure of arch height, the Chippaux-Smirak Index (CSI). The results showed that obese adults had lower arches than normal weight adults ( P < 0.05 ) . Arch height was related to velocity, double limb support time, stance time, step length, and foot rotation (all Ps < 0.05). Overweight participants with lower arches had lower velocities and higher double limb support times (all Ps < 0.05). The results have implications for aiding an increase in physical activity for overweight adults via intervening in adults’ arch height.
Among several highly fossiliferous localities in the Bloubank Valley (Gauteng, South Africa), the Cooper's Cave System has been known since 1938 and has produced a rich fossil assemblage, including ...some remains of the early hominin Paranthropus robustus. In 2001, excavations began at a new locality, Cooper's D, which dates to ∼1.4-1.5Ma. Although hominins are relatively rare in the assemblage, remains of cercopithecoid primates are much more common. Craniodental fossils currently indicate the possible presence of at least three large-bodied cercopithecoid primate genera at Cooper's D: Gorgopithecus, Papio, and Theropithecus. In this study, we identify and describe >100 cercopithecoid primate postcranial fossils representing all regions of the appendicular skeleton. The specimens come from several age classes and size morphs; more than one third of the fossils described are from sub-adult and juvenile individuals. The adult postcranial fossils vary substantially in size, with body masses estimated between 30 and 60kg (from 16 of the better preserved specimens). The functional morphology of the postcranial remains indicate that these elements come from animals that likely utilized terrestrial substrates, but they remain difficult to definitively attribute to Gorgopithecus, Theropithecus, or Papio given the absence of associated skeletons. The smaller specimens likely belong to Papio while the larger ones can be attributed to the other two genera. Because Cooper's D has also yielded fossils of the early hominin Paranthropus robustus, this raises the question of how these four large-bodied, mostly terrestrial primates sympatrically utilized the landscape.
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