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Diagenetic distortion can be a major obstacle to collecting quantitative shape data on paleontological specimens, especially for three-dimensional geometric morphometric analysis. Here we utilize the recently-published algorithmic symmetrization method of fossil reconstruction and compare it to the more traditional reflection & averaging approach. In order to have an objective test of this method, five casts of a female cranium of Papio hamadryas kindae were manually deformed while the plaster hardened. These were subsequently "retrodeformed" using both algorithmic symmetrization and reflection & averaging and then compared to the original, undeformed specimen. We found that in all cases, algorithmic retrodeformation improved the shape of the deformed cranium and in four out of five cases, the algorithmically symmetrized crania were more similar in shape to the original crania than the reflected & averaged reconstructions. In three out of five cases, the difference between the algorithmically symmetrized crania and the original cranium could be contained within the magnitude of variation among individuals in a single subspecies of Papio. Instances of asymmetric distortion, such as breakage on one side, or bending in the axis of symmetry, were well handled, whereas symmetrical distortion remained uncorrected. This technique was further tested on a naturally deformed and fossilized cranium of Paradolichopithecus arvernensis. Results, based on a principal components analysis and Procrustes distances, showed that the algorithmically symmetrized Paradolichopithecus cranium was more similar to other, less-deformed crania from the same species than was the original. These results illustrate the efficacy of this method of retrodeformation by algorithmic symmetrization for the correction of asymmetrical distortion in fossils. Symmetrical distortion remains a problem for all currently developed methods of retrodeformation.

'Suspensory locomotion' is an expression that encompasses a series of specialized forms of locomotion that mainly orthograde primates use to achieve below-branch traveling. It implies a number of features in the entire body associated with the use of the forelimb in overhead positions. The glenohumeral joint is one of the main joints involved in effective suspensory locomotion, being subject to a delicate balance between the high degree of mobility and stabilization needed to successfully engage in suspensory behaviors. Here, we present a 3D geometric morphometric study that explores the form of the proximal humerus of six orthograde and semi-orthograde genera ( Hylobates, Pongo, Pan, Gorilla, Ateles, and Lagothrix) and a pronograde genus, Colobus, to determine to what extent suspensory locomotor requirements are driving the shape of this epiphysis. Results show the presence of a morphocline related to degree of suspension in the shape of the articular surface, with highly suspensory taxa (i.e., Hylobates) exhibiting particular morphological traits at the articular surface that provide a greater range of circumduction. The placement and orientation of the rotator cuff muscles' insertion sites on the tubercles appear associated with the divergent forces operating at the joint in quadrupedal or above-head use of the hand. Am. J. Primatol. 77:1-19, 2015. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The morphology of the distal portion of the hominoid ulna is poorly studied despite its important functional role at the wrist joint. There are five qualitatively well-described fossil hominin distal ulnae belonging to Australopithecus afarensis and Australopithecus africanus, but there have been few efforts to quantify their morphology or relate it to their functional abilities. This article presents an effort to do so, using three-dimensional geometric morphometrics to analyze the shape of the distal ulna of the Plio-Pleistocene hominins and an extant comparative sample of great apes and humans. For the extant taxa, results show that the morphology of Pan and Pongo is distinct from that of Homo, and that these differences are likely related to climbing, clambering and below-branch suspension in the former, and the release of the limbs from locomotion and (potentially) tool manufacture in the latter. For the australopiths, results indicate that the A. afarensis sample is relatively heterogeneous. These results are driven by the morphology of A.L. 333-12, which is the largest ulna in the sample and has a unique combination of traits when compared with the other two A. afarensis specimens. Overall, the morphology of all the hominins was most consistent with the pattern displayed by extant great apes, and specifically Pan and Pongo; however, large overlap in shape in the distal ulna in the extant sample indicates that other areas of the skeleton may be more informative for functional analyses., (© 2014 Wiley Periodicals, Inc.)

Researchers often attempt to use limb proportions to ascertain the locomotor repertoires of fossil hominins. This can be problematic as there are few skeletons in the fossil record that preserve both a full forelimb and hindlimb; therefore, estimates of full limb lengths are typically associated with substantial error. In this study, two-block partial least squares analyses were used to examine covariation between forelimb and hindlimb elements in extant hominoids and fossil hominins. This has the benefit of including both forelimb and hindlimb in a type of functional analysis without necessitating an accurate length estimate. There is a high degree of covariation between forelimb and hindlimb segments in the mixed species sample, particularly in the proximal ulna, distal humerus, and proximal/distal femur and that shape covariation is significantly correlated with intermembral indices in the extant taxa. Overall, the fossil hominins most closely resembled modern humans with the exception of analyses utilizing the distal femur where some occupied a unique morphological position; thus, some fossil hominins likely possessed locomotor capabilities similar to modern humans, whereas others likely represent a unique morphological compromise between terrestrial bipedality and other positional behaviors not present among extant hominoids., (Copyright © 2012 Wiley Periodicals, Inc.)

One of the long-standing arguments about the evolution of bipedality centers on the locomotor pattern used by the last common ancestor (LCA) of apes and humans. In particular, knuckle-walking has been suggested as this locomotor pattern on the basis of shared morphology in the upper limb between African apes and humans and phylogenetic parsimony. Using three-dimensional geometric morphometrics, this study tests whether the distal radius of extant hominoids is sufficient for determining locomotor pattern and the affiliations of Plio-Pleistocene hominins to the extant taxa. Results indicate that while the entire radius differentiates the extant taxa very well by locomotor pattern, the distal radius fails to clearly differentiate the extant taxa. The sigmoid notch of the distal radius is the anatomical feature that differs most among the extant taxa, and its variability broadly correlates with necessary mobility at the wrist joint. Principal components and discriminant function analyses indicate that early hominins are affiliated with a variety of extant taxa with different locomotor patterns. Overall, the bony anatomy of the distal radius of early hominins points towards something adapted for a wide variety of locomotor postures., (Copyright © 2012 Wiley Periodicals, Inc.)