The Cervical Vertebrae of KSD-VP-1/1 (original) (raw)
Related papers
The role of allometry and posture in the evolution of the hominin subaxial cervical spine
Journal of human evolution, 2017
Cervical vertebrae not only protect the spinal cord but also are the insertion and origin points for muscles related to the movement of the head, upper limb, and trunk, among others, and are thus important elements in primate evolution. While previous work has been undertaken on the first two cervical vertebrae, there is a dearth of studies on the subaxial cervical spine in hominines. In this paper, we provide detailed morphological information on two important aspects of the subaxial cervical vertebrae (C3 - C7): mid-sagittal morphology and superior facet orientation. We studied large samples of African apes including modern humans and the most complete fossil hominin subaxial cervical vertebrae using both traditional and geometric morphometrics. There are significant differences between extant hominoids related to the relative length and orientation of the spinous process as well as to the orientation of the articular facets, which are related to size, locomotion, and neck posture...
The cervical spine of Australopithecus sediba
Cervical vertebrae are rare in the early hominin fossil record, presenting a challenge for understanding the evolution of the neck and head carriage in hominin evolution. Here, we examine the cervical vertebrae of Australopithecus sediba, which unlike other South African taxa is known from associated cervical vertebrae. The A. sediba cervical vertebrae exhibit human-like values for wedging, pedicle cross-sectional areas, and articular facet heights, indicating reduced ventral loading relative to African apes. These features combine with a pattern of vertebral body bone distribution and caudally progressive size expansion suggesting a mode of cervical lordosis, load mitigation, and head carriage similar to humans and distinct from the cantilevered mode of head carriage of the extant African great apes. Yet these derived features in A. sediba are accompanied by ape-like vertebral body and dorsal pillar sizes, articular facet orientation, and uncinate process morphology signaling reduced lateral and rotational coupled movements between vertebral elements and indicate a considerably stiffer neck than in humans. A primitively long and horizontally-oriented C7 spinous process is likely related to a prognathic viscer-ocranium, although the complimentary C3 spinous process is short, implying large moments emanating from scapular and shoulder elevators rather than large muscles of head stabilization. Cross-sectional spinous process shape and robust anterior tubercles similarly signal increased arm elevation consistent with climbing behavior in corroboration with arboreal signatures previously observed in the shoulder, arms, and hand of A. sediba. Spinal canal shape and size suggests that A. sediba lacked the cervical spinal cord enlargement of Homo that confers humans with enhanced motor control to the upper limbs. The cervical spine of A. sediba thus presents a mosaic of primitive and derived characters, with anatomical features relating to neck posture and head carriage mirroring humans juxtaposed with most other aspects of functional anatomy resembling chimpanzees.
The Vertebral Column of Australopithecus sediba
Two partial vertebral columns of Australopithecus sediba grant insight into aspects of early hominin spinal mobility, lumbar curvature, vertebral formula, and transitional vertebra position. Au. sediba likely possessed five non-rib-bearing lumbar vertebrae and five sacral elements, the same configuration that occurs modally in modern humans. This finding contrasts with other interpretations of early hominin regional vertebral numbers. Importantly, the transitional vertebra is distinct from and above the last rib-bearing vertebra in Au. sediba, resulting in a functionally longer lower back. This configuration, along with a strongly wedged last lumbar vertebra and other indicators of lordotic posture, would have contributed to a highly flexible spine that is derived compared with earlier members of the genus Australopithecus and similar to that of the Nariokotome Homo erectus skeleton.
2017 The Vertebrae and Ribs of Homo naledi - Copy.pdf
Hominin evolution featured shifts from a trunk shape suitable for climbing and housing a large gut to a trunk adapted to bipedalism and higher quality diets. Our knowledge regarding the tempo, mode, and context in which these derived traits evolved has been limited, based largely on a small-bodied Australopithecus partial skeleton (A.L. 288-1; "Lucy") and a juvenile Homo erectus skeleton (KNM-WT 15000; "Turkana Boy"). Two recent discoveries, of a large-bodied Australopithecus afarensis (KSD-VP-1/1) and two Australopithecus sediba partial skeletons (MH1 and MH2), have added to our understanding of thorax evolution; however, little is known about thorax morphology in early Homo. Here we describe hominin vertebrae, ribs, and sternal remains from the Dinaledi chamber of the Rising Star cave system attributed to Homo naledi. Although the remains are highly fragmented, the best-preserved specimensdtwo lower thoracic vertebrae and a lower ribdwere found in association and belong to a small-bodied individual. A second lower rib may belong to this individual as well. All four of these individual elements are amongst the smallest known in the hominin fossil record. H. naledi is characterized by robust, relatively uncurved lower ribs and a relatively large spinal canal. We expect that the recovery of additional material from Rising Star Cave will clarify the nature of these traits and shed light on H. naledi functional morphology and phylogeny.
The Spine of Early Pleistocene Homo
Spinal Evolution, 2019
In this chapter, we summarize vertebral remains from early Pleistocene Homo, including H. erectus, as well as H. naledi and H. floresiensis fossils from the Middle and Late Pleistocene, respectively. Two partial immature H. erectus skeletons where vertebrae are well represented are KNM-WT 15000 (“Turkana boy”) and the D2700 individual from Dmanisi. Vertebrae from H. naledi are also considered here, including those from the LES1 partial skeleton (“Neo”), despite their younger date to the Middle Pleistocene. We review the fossil record of presacral vertebrae in early Homo, and summarize work on the functional morphology, metameric patterning, and postcranial neuroanatomy of early Homo, comparing and contrasting the presacral spine with their putative australopith forbears and extant apes and humans. Based on the current evidence, the vertebral column of H. erectus possessed a modal number of twelve thoracic and five lumbar segments, as is the case in australopiths, as well as modern humans. The spine of H. erectus reveals key changes relative to earlier hominins, with an expanded thoracolumbar spinal canal offering increased neurovascular capacities, and a ventral pillar (formed by the vertebral bodies) better equipped to mitigate compressive loads and provide energy return. These biological developments are germane to understanding the advent of derived human behaviors, including efficient long-range locomotion and the first hominin expansion out of Africa.
The Neandertal vertebral column: 1-The cervical spine
This paper provides a metric analysis of the Neandertal cervical spine in relation to modern human variation. All seven cervical vertebrae have been analysed. Metric data from eight Neandertal individuals are compared with a large sample of modern humans. The significance of morphometric differences is tested using both z-scores and two-tailed Wilcoxon signed rank tests. The results identify significant metric and morphological differences between Neandertals and modern humans in all seven cervical vertebrae. Neandertal vertebrae are mediolaterally wider and dorsoventrally longer than modern humans, due in part to longer and more horizontally oriented spinous processes. This suggests that Neandertal cervical morphology was more stable in both mid-sagittal and coronal planes. It is hypothesized that the differences in cranial size and shape in the Neandertal and modern human lineages from their Middle Pleistocene ancestors could account for some of the differences in the neck anatomy between these species.Este artículo proporciona un análisis métrico de la columna cervical de los Neandertales, comparándola a la variación presente en los humanos modernos. Las siete vértebras cervicales han sido analizadas: datos métricos de siete Neandertales son comparados a una gran muestra de humanos modernos. El grado de significación de las diferencias morfométricas es testado usando z-scores y la prueba de signos de Wilcoxon con dos colas. Los resultados de este estudio indican que hay diferencias métricas y morfológicas significativas entre los Neandertales y los humanos modernos en todas las vértebras cervicales. Las vértebras cervicales de los Neandertales son más anchas mediolateralmente y más largas dorsoventralmente, en parte debido a apófisis espinosas más largas y orientadas más horizontalmente. Esto sugiere que el cuello de los Neandertales era más estable tanto en el plano medio-sagital como en el plano coronal. Hipotetizamos que las diferencias en el tamaño y forma del cráneo acontecidas desde el Pleistoceno Medio tanto en el linaje Neandertal como en nuestro propio linaje podrían explicar algunas de las diferencias entre las dos especies.
The vertebrae and ribs of Homo naledi
Hominin evolution featured shifts from a trunk shape suitable for climbing and housing a large gut to a trunk adapted to bipedalism and higher quality diets. Our knowledge regarding the tempo, mode, and context in which these derived traits evolved has been limited, based largely on a small-bodied Aus-tralopithecus partial skeleton (A.L. 288-1; " Lucy ") and a juvenile Homo erectus skeleton (KNM-WT 15000; " Turkana Boy "). Two recent discoveries, of a large-bodied Australopithecus afarensis (KSD-VP-1/1) and two Australopithecus sediba partial skeletons (MH1 and MH2), have added to our understanding of thorax evolution; however, little is known about thorax morphology in early Homo. Here we describe hominin vertebrae, ribs, and sternal remains from the Dinaledi chamber of the Rising Star cave system attributed to Homo naledi. Although the remains are highly fragmented, the best-preserved specimensdtwo lower thoracic vertebrae and a lower ribdwere found in association and belong to a small-bodied individual. A second lower rib may belong to this individual as well. All four of these individual elements are amongst the smallest known in the hominin fossil record. H. naledi is characterized by robust, relatively uncurved lower ribs and a relatively large spinal canal. We expect that the recovery of additional material from Rising Star Cave will clarify the nature of these traits and shed light on H. naledi functional morphology and phylogeny.
2019
The early hominin (Ardipithecus and Australopithecus) fossil record contains over 100 preserved vertebral elements (n = 107; approximately half of which are well-preserved), ~65% of which have not been described since the turn of the millennium. Many are fragments, some for which detailed descriptions are pending (e.g., those of Australopithecus anamensis). Australopithecus afarensis and Australopithecus sediba are known from cervical, thoracic, and lumbar vertebrae, whereas Australopithecus africanus is known from thoracic and lumbar vertebrae but not cervical vertebrae. A partial skeleton from Member 4 of Sterkfontein, StW 573, preserves vertebrae from all presacral regions, but its species designation is debated and not yet formalized in the literature. Other early hominin species, such as Sahelanthropus tchadensis, Orrorin tugenensis, Ardipithecus kadabba, Australopithecus deyiremeda, Australopithecus bahrelghazali, and Australopithecus garhi, do not preserve vertebrae. Vertebra...
The vertebral column plays a central role in the evolution and performance of positional behaviors, including upright posture and bipedal locomotion in the human lineage. The lumbar column, in particular, is associated with locomotor function. As such, its numerical composition has been a major source of contention in the paleoanthropological literature. Ever since description and interpretation of the nearly complete thoracolumbar vertebral column of Sts 14 (Australopithecus africanus), researchers have, with few exceptions, consistently stated that early hominins possessed six lumbar vertebrae (
Spinal posture has vast biomechanical, locomotor and pathological implications in hominins. Assessing the curvatures of the spine of fossil hominins can provide important information towards the understanding of their paleobiology. Unfortunately, complete hominin spines are very rarely preserved in the fossil record. The Neanderthal partial skeleton, Kebara 2 from Israel, constitutes a remarkable exception, representing an almost complete spine and pelvis. The aim of this study is, therefore, to create a new 3D virtual reconstruction of the spine of Kebara 2. To build the model, we used the CT scans of the sacrum, lumbar and thoracic vertebrae of Kebara 2, captured its 3D morphology, and, using visualization software (Amira 5.2©), aligned the 3D reconstruction of the original bones into the spinal curvature. First we aligned the sacrum and then we added one vertebra at a time, until the complete spine (T1-S5) was intact. The amount of spinal curvature (lordosis and kyphosis), the sacral orientation, and the coronal plane deviation was determined based on the current literature or measured and calculated specifically for this study based on published methods. This reconstruction provides, for the first time, a complete 3D virtual reconstruction of the spine of an extinct hominin. The spinal posture and spinopelvic alignment of Kebara 2 show a unique configuration compared with that of modern humans, suggesting locomotor and weight-bearing differences between the two. The spinal posture of Kebara 2 also shows slight asymmetry in the coronal plane. Stature estimation of Kebara 2 based on spinal length confirms that the height of Kebara 2 was around 170 cm. This reconstruction can now serve as the basis for a more complete reconstruction of the Kebara 2 specimen, which will include other parts of this remarkable fossil, such as the pelvis, the rib cage and the cervical spine.