Bipedal trackways discovered in 1978 at Laetoli site G, Tanzania and dated to 3.66 million years ... more Bipedal trackways discovered in 1978 at Laetoli site G, Tanzania and dated to 3.66 million years ago are widely accepted as the oldest unequivocal evidence of obligate bipedalism in the human lineage1–3. Another trackway discovered two years earlier at nearby site A was partially excavated and attributed to a hominin, but curious affinities with bears (ursids) marginalized its importance to the paleoanthropological community, and the location of these footprints fell into obscurity3–5. In 2019, we located, excavated and cleaned the site A trackway, producing a digital archive using 3D photogrammetry and laser scanning. Here we compare the footprints at this site with those of American black bears, chimpanzees and humans, and we show that they resemble those of hominins more than ursids. In fact, the narrow step width corroborates the original interpretation of a small, cross-stepping bipedal hominin. However, the inferred foot proportions, gait parameters and 3D morphologies of foot...
Objective. The purpose of this study is to describe the three-dimensional morphometry of the brac... more Objective. The purpose of this study is to describe the three-dimensional morphometry of the brachialis muscle at its distal attachment to the ulna. Methods. Fifty cadaveric elbows were dissected and the brachialis distal insertion was isolated on the ulna bone and probed with a three-dimensional digitizer, to create a three-dimensional model of the footprint. Measurements and analysis of each footprint shape were recorded and compared based on gender and size. Results. There was significant gender difference in the surface length (P= 0.002) and projected length (P= 0.001) of the brachialis footprint. The shapes of the footprint also differed among the specimens. Conclusion. The shape of the brachialis muscle insertion differed among all the specimens without significant variation in gender or sides. There was also a significant difference in muscle length between males and females with little difference in the width and surface area. Significance. The information obtained from this...
Introduction. The purpose of this study is to describe the inner synovial membrane (SM) of the an... more Introduction. The purpose of this study is to describe the inner synovial membrane (SM) of the anterior elbow capsule, both qualitatively and quantitatively. Materials and Methods. Twenty-two cadaveric human elbows were dissected and the distal humerus and SM attachments were digitized using a digitizer. The transepicondylar line (TEL) was used as the primary descriptor of various landmarks. The distance between the medial epicondyle and medial SM edge, SM apex overlying the coronoid fossa, the central SM nadir, and the apex of the SM insertion overlying the radial fossa and distance from the lateral epicondyle to lateral SM edge along the TEL were measured and further analyzed. Gender and side-to-side statistical comparisons were calculated. Results. The mean age of the subjects was 80.4 years, with six male and five female cadavers. The SM had a distinctive double arched attachment overlying the radial and coronoid fossae. No gender-based or side-to-side quantitative differences w...
Homo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Cha... more Homo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Chamber of the Rising Star cave system, Cradle of Humankind, South Africa. This species is characterized by body mass and stature similar to small-bodied human populations but a small endocranial volume similar to australopiths. Cranial morphology of H. naledi is unique, but most similar to early Homo species including Homo erectus, Homo habilis or Homo rudolfensis. While primitive, the dentition is generally small and simple in occlusal morphology. H. naledi has humanlike manipulatory adaptations of the hand and wrist. It also exhibits a humanlike foot and lower limb. These humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, pelvis and proximal femur. Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa.
A nearly complete right hand of an adult hominin was recovered from the Rising Star cave system, ... more A nearly complete right hand of an adult hominin was recovered from the Rising Star cave system, South Africa. Based on associated hominin material, the bones of this hand are attributed to Homo naledi. This hand reveals a long, robust thumb and derived wrist morphology that is shared with Neandertals and modern humans, and considered adaptive for intensified manual manipulation. However, the finger bones are longer and more curved than in most australopiths, indicating frequent use of the hand during life for strong grasping during locomotor climbing and suspension. These markedly curved digits in combination with an otherwise human-like wrist and palm indicate a significant degree of climbing, despite the derived nature of many aspects of the hand and other regions of the postcranial skeleton in H. naledi.
Despite the relatively large size of anthropoid incisors in relation to the remainder of the dent... more Despite the relatively large size of anthropoid incisors in relation to the remainder of the dental arcade, and their prominent role in the preprocessing of food prior to ingestion, comparatively little is known about the functional morphology of anthropoid incisor shape and crown curvature. The relationship between incisor allometry and diet is well documented for both platyrrhines and catarrhines; however, similar relationships between incisor shape and crown curvature have to date only been reported for living and fossil members of the superfamily Hominoidea. Given the limited taxonomic diversity among the extant members of that group, it is difficult to firmly establish the relative influence of phylogeny and dietary function in the governance of incisor crown curvature. Unlike hominoids, which are represented by only five living genera, extant platyrrhines are a more varied group that includes 16 ecologically diverse genera. In an effort to clarify the functional relationship between maxillary and mandibular incisor crown curvature and diet, this study uses high resolution polynomial curve fitting to quantify mesiodistal and cervicoincisal curvature for a taxonomically diverse platyrrhine sample (n = 133 individuals representing 18 taxa) with well documented dietary behavior. Results were consistent with prior analyses of hominoid incisor curvature and identify a significant and positive correlation between incisor crown curvature and diet such that increasing curvature is associated with a proportionate increase in frugivory. These results are independent confirmation of the results reported from a previous analysis of hominoid incisor curvature and provide new evidence to suggest that diet is the primary governing factor influencing anthropoid incisor curvature.
Bipedal trackways discovered in 1978 at Laetoli site G, Tanzania and dated to 3.66 million years ... more Bipedal trackways discovered in 1978 at Laetoli site G, Tanzania and dated to 3.66 million years ago are widely accepted as the oldest unequivocal evidence of obligate bipedalism in the human lineage1–3. Another trackway discovered two years earlier at nearby site A was partially excavated and attributed to a hominin, but curious affinities with bears (ursids) marginalized its importance to the paleoanthropological community, and the location of these footprints fell into obscurity3–5. In 2019, we located, excavated and cleaned the site A trackway, producing a digital archive using 3D photogrammetry and laser scanning. Here we compare the footprints at this site with those of American black bears, chimpanzees and humans, and we show that they resemble those of hominins more than ursids. In fact, the narrow step width corroborates the original interpretation of a small, cross-stepping bipedal hominin. However, the inferred foot proportions, gait parameters and 3D morphologies of foot...
Objective. The purpose of this study is to describe the three-dimensional morphometry of the brac... more Objective. The purpose of this study is to describe the three-dimensional morphometry of the brachialis muscle at its distal attachment to the ulna. Methods. Fifty cadaveric elbows were dissected and the brachialis distal insertion was isolated on the ulna bone and probed with a three-dimensional digitizer, to create a three-dimensional model of the footprint. Measurements and analysis of each footprint shape were recorded and compared based on gender and size. Results. There was significant gender difference in the surface length (P= 0.002) and projected length (P= 0.001) of the brachialis footprint. The shapes of the footprint also differed among the specimens. Conclusion. The shape of the brachialis muscle insertion differed among all the specimens without significant variation in gender or sides. There was also a significant difference in muscle length between males and females with little difference in the width and surface area. Significance. The information obtained from this...
Introduction. The purpose of this study is to describe the inner synovial membrane (SM) of the an... more Introduction. The purpose of this study is to describe the inner synovial membrane (SM) of the anterior elbow capsule, both qualitatively and quantitatively. Materials and Methods. Twenty-two cadaveric human elbows were dissected and the distal humerus and SM attachments were digitized using a digitizer. The transepicondylar line (TEL) was used as the primary descriptor of various landmarks. The distance between the medial epicondyle and medial SM edge, SM apex overlying the coronoid fossa, the central SM nadir, and the apex of the SM insertion overlying the radial fossa and distance from the lateral epicondyle to lateral SM edge along the TEL were measured and further analyzed. Gender and side-to-side statistical comparisons were calculated. Results. The mean age of the subjects was 80.4 years, with six male and five female cadavers. The SM had a distinctive double arched attachment overlying the radial and coronoid fossae. No gender-based or side-to-side quantitative differences w...
Homo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Cha... more Homo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Chamber of the Rising Star cave system, Cradle of Humankind, South Africa. This species is characterized by body mass and stature similar to small-bodied human populations but a small endocranial volume similar to australopiths. Cranial morphology of H. naledi is unique, but most similar to early Homo species including Homo erectus, Homo habilis or Homo rudolfensis. While primitive, the dentition is generally small and simple in occlusal morphology. H. naledi has humanlike manipulatory adaptations of the hand and wrist. It also exhibits a humanlike foot and lower limb. These humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, pelvis and proximal femur. Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa.
A nearly complete right hand of an adult hominin was recovered from the Rising Star cave system, ... more A nearly complete right hand of an adult hominin was recovered from the Rising Star cave system, South Africa. Based on associated hominin material, the bones of this hand are attributed to Homo naledi. This hand reveals a long, robust thumb and derived wrist morphology that is shared with Neandertals and modern humans, and considered adaptive for intensified manual manipulation. However, the finger bones are longer and more curved than in most australopiths, indicating frequent use of the hand during life for strong grasping during locomotor climbing and suspension. These markedly curved digits in combination with an otherwise human-like wrist and palm indicate a significant degree of climbing, despite the derived nature of many aspects of the hand and other regions of the postcranial skeleton in H. naledi.
Despite the relatively large size of anthropoid incisors in relation to the remainder of the dent... more Despite the relatively large size of anthropoid incisors in relation to the remainder of the dental arcade, and their prominent role in the preprocessing of food prior to ingestion, comparatively little is known about the functional morphology of anthropoid incisor shape and crown curvature. The relationship between incisor allometry and diet is well documented for both platyrrhines and catarrhines; however, similar relationships between incisor shape and crown curvature have to date only been reported for living and fossil members of the superfamily Hominoidea. Given the limited taxonomic diversity among the extant members of that group, it is difficult to firmly establish the relative influence of phylogeny and dietary function in the governance of incisor crown curvature. Unlike hominoids, which are represented by only five living genera, extant platyrrhines are a more varied group that includes 16 ecologically diverse genera. In an effort to clarify the functional relationship between maxillary and mandibular incisor crown curvature and diet, this study uses high resolution polynomial curve fitting to quantify mesiodistal and cervicoincisal curvature for a taxonomically diverse platyrrhine sample (n = 133 individuals representing 18 taxa) with well documented dietary behavior. Results were consistent with prior analyses of hominoid incisor curvature and identify a significant and positive correlation between incisor crown curvature and diet such that increasing curvature is associated with a proportionate increase in frugivory. These results are independent confirmation of the results reported from a previous analysis of hominoid incisor curvature and provide new evidence to suggest that diet is the primary governing factor influencing anthropoid incisor curvature.
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