The Experts below are selected from a list of 3312 Experts worldwide ranked by ideXlab platform
Martin Haeusler - One of the best experts on this subject based on the ideXlab platform.
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revisiting scoliosis in the knm wt 15000 Homo Erectus skeleton
Journal of Human Evolution, 2014Co-Authors: Regula Schiess, Thomas Boeni, Frank J Ruhli, Martin HaeuslerAbstract:Abstract Owing to its completeness, the 1.5 million year old Nariokotome boy skeleton KNM-WT 15000 is central for understanding the skeletal biology of Homo Erectus. Nevertheless, since the reported asymmetries and distortions of Nariokotome boy's axial skeleton suggest adolescent idiopathic scoliosis, possibly associated with congenital skeletal dysplasia, it is questionable whether it still can be used as a reference for H. Erectus. Recently, however, the presence of skeletal dysplasia has been refuted. Here, we present a morphological and morphometric reanalysis of the assertion of idiopathic scoliosis. We demonstrate that unarticulated vertebral columns of non-scoliotic and scoliotic individuals can be distinguished based on the lateral deviation of the spinous process, lateral and sagittal wedging, vertebral body torsion, pedicle thickness asymmetry, and asymmetry of superior and inferior articular facet areas. A principal component analysis of the overall asymmetry of all seven vertebral shape variables groups KNM-WT 15000 within non-scoliotic modern humans. There is, however, an anomaly of vertebrae T1–T2 that is compatible with a short left convex curve at the uppermost thoracic region, possibly due to injury or local growth dysbalance. Asymmetries of the facet joints L3–L5 suggest a local right convex curve in the lower lumbar region that probably resulted from juvenile traumatic disc herniation. This pattern is incompatible with adolescent idiopathic scoliosis or other types of scoliosis, including congenital, neuromuscular or syndromic scoliosis. It is, however, consistent with a recent reanalysis of the rib cage that did not reveal any asymmetry. Except for these possibly trauma-related anomalies, the Nariokotome boy fossil therefore seems to belong to a normal H. Erectus youth without evidence for adolescent idiopathic scoliosis or other severe pathologies of the axial skeleton.
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no skeletal dysplasia in the nariokotome boy knm wt 15000 Homo Erectus a reassessment of congenital pathologies of the vertebral column
American Journal of Physical Anthropology, 2013Co-Authors: Regula Schiess, Martin HaeuslerAbstract:The Nariokotome boy skeleton KNM-WT 15000 is the most complete Homo Erectus fossil and therefore is key for understanding human evolution. Nevertheless, since Latimer and Ohman (2001) reported on severe congenital pathology in KNM-WT 15000, it is questionable whether this skeleton can still be used as reference for Homo Erectus skeletal biology. The asserted pathologies include platyspondylic and diminutive vertebrae implying a disproportionately short stature; spina bifida; condylus tertius; spinal stenosis; and scoliosis. Based on this symptom complex, the differential diagnosis of spondyloepiphyseal dysplasia tarda, an extremely rare form of skeletal dysplasia, has been proposed. Yet, our reanalysis of these pathologies shows that the shape of the KNM-WT 15000 vertebrae matches that of normal modern human adolescents. The vertebrae are not abnormally flat, show no endplate irregularities, and thus are not platyspondylic. As this is the hallmark of spondyloepiphyseal dysplasia tarda and related forms of skeletal dysplasia, the absence of platyspondyly refutes axial dysplasia and disproportionate dwarfism. Furthermore, we neither found evidence for spina bifida occulta nor manifesta, whereas the condylus tertius, a developmental anomaly of the cranial base, is not related to skeletal dysplasias. Other fossils indicate that the relatively small size of the vertebrae and the narrow spinal canal are characteristics of early hominins rather than congenital pathologies. Except for the recently described signs of traumatic lumbar disc herniation, the Nariokotome boy fossil therefore seems to belong to a normal Homo Erectus youth without pathologies of the axial skeleton.
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evidence for juvenile disc herniation in a Homo Erectus boy skeleton
Spine, 2013Co-Authors: Martin Haeusler, Regula Schiess, Thomas BoeniAbstract:Study design An analysis and differential diagnosis of bony alterations in the lower lumbar vertebrae of a Homo Erectus boy skeleton. Objective To analyze low back problems during early human evolution. Summary of background data Back problems in modern humans are often attributed to our upright, bipedal locomotion that is thought to place huge mechanical stresses on the vertebral column. However, little is known of this situation during the course of human evolution. Methods We analyzed the lower lumbar spine of the most complete early hominid skeleton, the 1.5-million-year-old Homo Erectus boy KNM-WT 15000 from Nariokotome, Kenya, who died at an age of approximately 8 years. We use bony alterations as indirect evidence for disc disease in the absence of soft tissue. Results We describe an extensive osteophytic anterior curved remodeling of the left superior articular process of L5 and formation of a new joint at the underside of the left pedicle of L4. This indicates collisional facet joint subluxation, most likely as the result of juvenile traumatic disc herniation. Conclusions This indirect evidence of possible juvenile disc herniation in a Homo Erectus boy skeleton represents the earliest known case of this typical human ailment that is intricately linked to upright bipedalism. The extensive bony remodeling of the articular processes of L4 and L5 suggests that the disc herniation occurred several months before his death. Disabling backache and recurrent sciatica might have, at least, temporarily restricted his daily activities, which indicates advanced social care and nursing in early Homo. We hypothesize that the early Homo intervertebral discs were more vulnerable to injury compared with modern humans because of a relatively small vertebral cross-sectional area.
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New vertebral and rib material point to modern bauplan of the Nariokotome Homo Erectus skeleton
Journal of Human Evolution, 2011Co-Authors: Martin Haeusler, Regula Schiess, Thomas BoeniAbstract:The double S shape of the vertebral column is one of the most important evolutionary adaptations to human bipedal locomotion, providing an optimal compromise between stability and mobility. It is commonly believed that a six element long lumbar spine facilitated the critical adoption of lumbar lordosis in early hominins, which contrasts with five lumbars in modern humans and four in chimpanzees and gorillas. This is mainly based on the juvenile Homo Erectus skeleton KNM-WT 15000 from Nariokotome, Kenya. Yet, the biomechanical advantage of a long lumbar spine is speculative. Here we present new vertebral and rib fragments of KNM-WT 15000. They demonstrate that the sixth to the last presacral vertebra possesses rib facets and therefore indicate the presence of only five lumbar and twelve thoracic segments, as is characteristic of modern humans. Moreover, they show that no additional element was located between the sixth to the last presacral vertebra and Th11 as suggested in the original description. The transition from thoracic to lumbar type orientation of the facet joints that takes place at Th11 is thus at the same segment as in over 40% of modern humans, suggesting an identical lumbar mobility and capacity for lordosis. Taken together, KNM-WT 15000 had one vertebra less than previously thought irrespective of whether rib-free lumbar vertebrae or vertebrae that bear lumbar-like articular processes are counted. Furthermore, the new rib fragments imply a rearrangement of the ribs that results in a symmetrical rib cage. This challenges previous claims for idiopathic or congenital scoliosis. We conclude that the bauplan of the hominin axial skeleton is more conservative than previously thought.
Arthur E Bettis - One of the best experts on this subject based on the ideXlab platform.
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last appearance of Homo Erectus at ngandong java 117 000 108 000 years ago
Nature, 2020Co-Authors: Yan Rizal, Arthur E Bettis, Rainer Grun, Yahdi Zaim, Kira E Westaway, Gerrit D Van Den Bergh, Michael J Morwood, Frank O Huffman, Renaud Joannesboyau, Richard M BaileyAbstract:Homo Erectus is the founding early hominin species of Island Southeast Asia, and reached Java (Indonesia) more than 1.5 million years ago1,2. Twelve H. Erectus calvaria (skull caps) and two tibiae (lower leg bones) were discovered from a bone bed located about 20 m above the Solo River at Ngandong (Central Java) between 1931 and 19333,4, and are of the youngest, most-advanced form of H. Erectus5–8. Despite the importance of the Ngandong fossils, the relationship between the fossils, terrace fill and ages have been heavily debated9–14. Here, to resolve the age of the Ngandong evidence, we use Bayesian modelling of 52 radiometric age estimates to establish—to our knowledge—the first robust chronology at regional, valley and local scales. We used uranium-series dating of speleothems to constrain regional landscape evolution; luminescence, 40argon/39argon (40Ar/39Ar) and uranium-series dating to constrain the sequence of terrace evolution; and applied uranium-series and uranium series–electron-spin resonance (US–ESR) dating to non-human fossils to directly date our re-excavation of Ngandong5,15. We show that at least by 500 thousand years ago (ka) the Solo River was diverted into the Kendeng Hills, and that it formed the Solo terrace sequence between 316 and 31 ka and the Ngandong terrace between about 140 and 92 ka. Non-human fossils recovered during the re-excavation of Ngandong date to between 109 and 106 ka (uranium-series minimum)16 and 134 and 118 ka (US–ESR), with modelled ages of 117 to 108 thousand years (kyr) for the H. Erectus bone bed, which accumulated during flood conditions3,17. These results negate the extreme ages that have been proposed for the site and solidify Ngandong as the last known occurrence of this long-lived species. Bayesian modelling of radiometric age estimates provides a robust chronology for Homo Erectus at Ngandong (Java), confirming that this site currently represents the last known occurrence of this species.
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new 1 5 million year old Homo Erectus maxilla from sangiran central java indonesia
Journal of Human Evolution, 2011Co-Authors: Yahdi Zaim, Russell L Ciochon, Arthur E Bettis, Roy Larick, Joshua M Polanski, Frederick E Grine, Yan Rizal, Robert G Franciscus, Matthew T Heizler, Lindsay K EavesAbstract:Sangiran (Solo Basin, Central Java, Indonesia) is the singular Homo Erectus fossil locale for Early Pleistocene Southeast Asia. Sangiran is the source for more than 80 specimens in deposits with 40 Ar/ 39 Ar ages of 1.51e0.9 Ma. In April 2001, we recovered a H. Erectus left maxilla fragment (preserving P 3 -M 2 ) from the Sangiran site of Bapang. The find spot lies at the base of the Bapang Formation type section in cemented gravelly sands traditionally called the Grenzbank Zone. Two meters above the find spot, pumice hornblende has produced an 40 Ar/ 39 Ar age of 1.51 � 0.08 Ma. With the addition of Bpg 2001.04,
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palaeoanthropology asian Homo Erectus converges in time
Nature, 2009Co-Authors: Russell L Ciochon, Arthur E BettisAbstract:Re-evaluation of the age of Zhoukoudian, a prominent site of Homo Erectus occupation in China, prompts a rethink of the species' distribution in both the temperate north and the equatorial south of east Asia.
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way out of africa early pleistocene paleoenvironments inhabited by Homo Erectus in sangiran java
Journal of Human Evolution, 2009Co-Authors: Arthur E Bettis, Russell L Ciochon, Roy Larick, Yahdi Zaim, Yan Rizal, Adrianne K Milius, Scott J Carpenter, Stephanie Tassiersurine, Daniel Murray, Sutinko BrontoAbstract:A sequence of paleosols in the Solo Basin, Central Java, Indonesia, documents the local and regional environments present when Homo Erectus spread through Southeast Asia during the early Pleistocene. The earliest human immigrants encountered a low-relief lake-margin landscape dominated by moist grasslands with open woodlands in the driest landscape positions. By 1.5 Ma, large streams filled the lake and the landscape became more riverine in nature, with riparian forests, savanna, and open woodland. Paleosol morphology and carbon isotope values of soil organic matter and pedogenic carbonates indicate a long-term shift toward regional drying or increased duration of the annual dry season through the early Pleistocene. This suggests that an annual dry season associated with monsoon conditions was an important aspect of the paleoclimate in which early humans spread from Africa to Southeast Asia.
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landscape development preceding Homo Erectus immigration into central java indonesia the sangiran formation lower lahar
Palaeogeography Palaeoclimatology Palaeoecology, 2004Co-Authors: Arthur E Bettis, Russell L Ciochon, Roy Larick, Mark K Reagan, Yahdi Zaim, Yan Rizal, Matthew T HeizlerAbstract:Abstract The Sangiran Dome is the primary stratigraphic window for the Solo Basin, a coastal feature on the Pliocene–Pleistocene Sunda subcontinent south margin. In the Dome, the Lower Lahar unit (LLU) is a lahar-type debris flow overlying near-shore marine sediments. The event that emplaced the LLU likely originated from sector collapse on a neighboring volcanic edifice. Freshwater mollusc fossils in the LLU indicate that swamps or shallow lakes lay between the edifice and the current Dome area. 40Ar/39Ar analyses on hornblende separates from six pumice lenses suggest that the LLU was deposited as early as 1.90±0.02 Ma. The event resulting in deposition of the LLU transformed late Pliocene near-shore marine environments into estuarine and marsh settings. Shortly thereafter, glacioeustatic sea level falls completed the local transition to fully terrestrial environments that attracted Homo Erectus to southernmost Sunda in the Early Pleistocene.
Regula Schiess - One of the best experts on this subject based on the ideXlab platform.
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revisiting scoliosis in the knm wt 15000 Homo Erectus skeleton
Journal of Human Evolution, 2014Co-Authors: Regula Schiess, Thomas Boeni, Frank J Ruhli, Martin HaeuslerAbstract:Abstract Owing to its completeness, the 1.5 million year old Nariokotome boy skeleton KNM-WT 15000 is central for understanding the skeletal biology of Homo Erectus. Nevertheless, since the reported asymmetries and distortions of Nariokotome boy's axial skeleton suggest adolescent idiopathic scoliosis, possibly associated with congenital skeletal dysplasia, it is questionable whether it still can be used as a reference for H. Erectus. Recently, however, the presence of skeletal dysplasia has been refuted. Here, we present a morphological and morphometric reanalysis of the assertion of idiopathic scoliosis. We demonstrate that unarticulated vertebral columns of non-scoliotic and scoliotic individuals can be distinguished based on the lateral deviation of the spinous process, lateral and sagittal wedging, vertebral body torsion, pedicle thickness asymmetry, and asymmetry of superior and inferior articular facet areas. A principal component analysis of the overall asymmetry of all seven vertebral shape variables groups KNM-WT 15000 within non-scoliotic modern humans. There is, however, an anomaly of vertebrae T1–T2 that is compatible with a short left convex curve at the uppermost thoracic region, possibly due to injury or local growth dysbalance. Asymmetries of the facet joints L3–L5 suggest a local right convex curve in the lower lumbar region that probably resulted from juvenile traumatic disc herniation. This pattern is incompatible with adolescent idiopathic scoliosis or other types of scoliosis, including congenital, neuromuscular or syndromic scoliosis. It is, however, consistent with a recent reanalysis of the rib cage that did not reveal any asymmetry. Except for these possibly trauma-related anomalies, the Nariokotome boy fossil therefore seems to belong to a normal H. Erectus youth without evidence for adolescent idiopathic scoliosis or other severe pathologies of the axial skeleton.
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no skeletal dysplasia in the nariokotome boy knm wt 15000 Homo Erectus a reassessment of congenital pathologies of the vertebral column
American Journal of Physical Anthropology, 2013Co-Authors: Regula Schiess, Martin HaeuslerAbstract:The Nariokotome boy skeleton KNM-WT 15000 is the most complete Homo Erectus fossil and therefore is key for understanding human evolution. Nevertheless, since Latimer and Ohman (2001) reported on severe congenital pathology in KNM-WT 15000, it is questionable whether this skeleton can still be used as reference for Homo Erectus skeletal biology. The asserted pathologies include platyspondylic and diminutive vertebrae implying a disproportionately short stature; spina bifida; condylus tertius; spinal stenosis; and scoliosis. Based on this symptom complex, the differential diagnosis of spondyloepiphyseal dysplasia tarda, an extremely rare form of skeletal dysplasia, has been proposed. Yet, our reanalysis of these pathologies shows that the shape of the KNM-WT 15000 vertebrae matches that of normal modern human adolescents. The vertebrae are not abnormally flat, show no endplate irregularities, and thus are not platyspondylic. As this is the hallmark of spondyloepiphyseal dysplasia tarda and related forms of skeletal dysplasia, the absence of platyspondyly refutes axial dysplasia and disproportionate dwarfism. Furthermore, we neither found evidence for spina bifida occulta nor manifesta, whereas the condylus tertius, a developmental anomaly of the cranial base, is not related to skeletal dysplasias. Other fossils indicate that the relatively small size of the vertebrae and the narrow spinal canal are characteristics of early hominins rather than congenital pathologies. Except for the recently described signs of traumatic lumbar disc herniation, the Nariokotome boy fossil therefore seems to belong to a normal Homo Erectus youth without pathologies of the axial skeleton.
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evidence for juvenile disc herniation in a Homo Erectus boy skeleton
Spine, 2013Co-Authors: Martin Haeusler, Regula Schiess, Thomas BoeniAbstract:Study design An analysis and differential diagnosis of bony alterations in the lower lumbar vertebrae of a Homo Erectus boy skeleton. Objective To analyze low back problems during early human evolution. Summary of background data Back problems in modern humans are often attributed to our upright, bipedal locomotion that is thought to place huge mechanical stresses on the vertebral column. However, little is known of this situation during the course of human evolution. Methods We analyzed the lower lumbar spine of the most complete early hominid skeleton, the 1.5-million-year-old Homo Erectus boy KNM-WT 15000 from Nariokotome, Kenya, who died at an age of approximately 8 years. We use bony alterations as indirect evidence for disc disease in the absence of soft tissue. Results We describe an extensive osteophytic anterior curved remodeling of the left superior articular process of L5 and formation of a new joint at the underside of the left pedicle of L4. This indicates collisional facet joint subluxation, most likely as the result of juvenile traumatic disc herniation. Conclusions This indirect evidence of possible juvenile disc herniation in a Homo Erectus boy skeleton represents the earliest known case of this typical human ailment that is intricately linked to upright bipedalism. The extensive bony remodeling of the articular processes of L4 and L5 suggests that the disc herniation occurred several months before his death. Disabling backache and recurrent sciatica might have, at least, temporarily restricted his daily activities, which indicates advanced social care and nursing in early Homo. We hypothesize that the early Homo intervertebral discs were more vulnerable to injury compared with modern humans because of a relatively small vertebral cross-sectional area.
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New vertebral and rib material point to modern bauplan of the Nariokotome Homo Erectus skeleton
Journal of Human Evolution, 2011Co-Authors: Martin Haeusler, Regula Schiess, Thomas BoeniAbstract:The double S shape of the vertebral column is one of the most important evolutionary adaptations to human bipedal locomotion, providing an optimal compromise between stability and mobility. It is commonly believed that a six element long lumbar spine facilitated the critical adoption of lumbar lordosis in early hominins, which contrasts with five lumbars in modern humans and four in chimpanzees and gorillas. This is mainly based on the juvenile Homo Erectus skeleton KNM-WT 15000 from Nariokotome, Kenya. Yet, the biomechanical advantage of a long lumbar spine is speculative. Here we present new vertebral and rib fragments of KNM-WT 15000. They demonstrate that the sixth to the last presacral vertebra possesses rib facets and therefore indicate the presence of only five lumbar and twelve thoracic segments, as is characteristic of modern humans. Moreover, they show that no additional element was located between the sixth to the last presacral vertebra and Th11 as suggested in the original description. The transition from thoracic to lumbar type orientation of the facet joints that takes place at Th11 is thus at the same segment as in over 40% of modern humans, suggesting an identical lumbar mobility and capacity for lordosis. Taken together, KNM-WT 15000 had one vertebra less than previously thought irrespective of whether rib-free lumbar vertebrae or vertebrae that bear lumbar-like articular processes are counted. Furthermore, the new rib fragments imply a rearrangement of the ribs that results in a symmetrical rib cage. This challenges previous claims for idiopathic or congenital scoliosis. We conclude that the bauplan of the hominin axial skeleton is more conservative than previously thought.
Yan Rizal - One of the best experts on this subject based on the ideXlab platform.
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last appearance of Homo Erectus at ngandong java 117 000 108 000 years ago
Nature, 2020Co-Authors: Yan Rizal, Arthur E Bettis, Rainer Grun, Yahdi Zaim, Kira E Westaway, Gerrit D Van Den Bergh, Michael J Morwood, Frank O Huffman, Renaud Joannesboyau, Richard M BaileyAbstract:Homo Erectus is the founding early hominin species of Island Southeast Asia, and reached Java (Indonesia) more than 1.5 million years ago1,2. Twelve H. Erectus calvaria (skull caps) and two tibiae (lower leg bones) were discovered from a bone bed located about 20 m above the Solo River at Ngandong (Central Java) between 1931 and 19333,4, and are of the youngest, most-advanced form of H. Erectus5–8. Despite the importance of the Ngandong fossils, the relationship between the fossils, terrace fill and ages have been heavily debated9–14. Here, to resolve the age of the Ngandong evidence, we use Bayesian modelling of 52 radiometric age estimates to establish—to our knowledge—the first robust chronology at regional, valley and local scales. We used uranium-series dating of speleothems to constrain regional landscape evolution; luminescence, 40argon/39argon (40Ar/39Ar) and uranium-series dating to constrain the sequence of terrace evolution; and applied uranium-series and uranium series–electron-spin resonance (US–ESR) dating to non-human fossils to directly date our re-excavation of Ngandong5,15. We show that at least by 500 thousand years ago (ka) the Solo River was diverted into the Kendeng Hills, and that it formed the Solo terrace sequence between 316 and 31 ka and the Ngandong terrace between about 140 and 92 ka. Non-human fossils recovered during the re-excavation of Ngandong date to between 109 and 106 ka (uranium-series minimum)16 and 134 and 118 ka (US–ESR), with modelled ages of 117 to 108 thousand years (kyr) for the H. Erectus bone bed, which accumulated during flood conditions3,17. These results negate the extreme ages that have been proposed for the site and solidify Ngandong as the last known occurrence of this long-lived species. Bayesian modelling of radiometric age estimates provides a robust chronology for Homo Erectus at Ngandong (Java), confirming that this site currently represents the last known occurrence of this species.
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new 1 5 million year old Homo Erectus maxilla from sangiran central java indonesia
Journal of Human Evolution, 2011Co-Authors: Yahdi Zaim, Russell L Ciochon, Arthur E Bettis, Roy Larick, Joshua M Polanski, Frederick E Grine, Yan Rizal, Robert G Franciscus, Matthew T Heizler, Lindsay K EavesAbstract:Sangiran (Solo Basin, Central Java, Indonesia) is the singular Homo Erectus fossil locale for Early Pleistocene Southeast Asia. Sangiran is the source for more than 80 specimens in deposits with 40 Ar/ 39 Ar ages of 1.51e0.9 Ma. In April 2001, we recovered a H. Erectus left maxilla fragment (preserving P 3 -M 2 ) from the Sangiran site of Bapang. The find spot lies at the base of the Bapang Formation type section in cemented gravelly sands traditionally called the Grenzbank Zone. Two meters above the find spot, pumice hornblende has produced an 40 Ar/ 39 Ar age of 1.51 � 0.08 Ma. With the addition of Bpg 2001.04,
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new reconstruction and morphological description of a Homo Erectus cranium skull ix tjg 1993 05 from sangiran central java
Journal of Human Evolution, 2011Co-Authors: Yousuke Kaifu, Hisao Baba, Yahdi Zaim, Yan Rizal, Iwan Kurniawan, Daisuke Kubo, Johan Arif, Fachroel AzizAbstract:Skull IX (Tjg-1993.05) was unearthed from the upper stratigraphic zone (Bapang-AG levels) of the hominin-bearing sequence in Sangiran. This remarkably complete cranial specimen of Homo Erectus from the early Pleistocene of Java preserves substantial portions of the vault and face. However, the distortion present in the original reconstruction has hampered detailed documentation of its morphological characteristics. We here report a new reconstruction of Skull IX that successfully recovers the original morphology and significantly differs from previous reconstructions. Detailed morphological description and the results of initial comparative analyses based on this new reconstruction are provided. The endocranial volume of Skull IX was measured as 870 cc using micro-CT data. The neurocranium of Skull IX is slightly smaller than the so far recorded smallest cranium from this zone, suggesting this individual was female. In most, but not all, aspects of the cranial vault form, details of the external surface structures, and facial morphology, Skull IX exhibits numerous similarities to the other Bapang-AG H. Erectus specimens, indicating that it belonged to the Bapang-AG H. Erectus population. Drawing on the expanded fossil sample of this chronoregional H. Erectus group, we discuss their evolutionary status, degree of sexual dimorphism, and facial morphological variation in Afro-Asian earlier Homo specimens.
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way out of africa early pleistocene paleoenvironments inhabited by Homo Erectus in sangiran java
Journal of Human Evolution, 2009Co-Authors: Arthur E Bettis, Russell L Ciochon, Roy Larick, Yahdi Zaim, Yan Rizal, Adrianne K Milius, Scott J Carpenter, Stephanie Tassiersurine, Daniel Murray, Sutinko BrontoAbstract:A sequence of paleosols in the Solo Basin, Central Java, Indonesia, documents the local and regional environments present when Homo Erectus spread through Southeast Asia during the early Pleistocene. The earliest human immigrants encountered a low-relief lake-margin landscape dominated by moist grasslands with open woodlands in the driest landscape positions. By 1.5 Ma, large streams filled the lake and the landscape became more riverine in nature, with riparian forests, savanna, and open woodland. Paleosol morphology and carbon isotope values of soil organic matter and pedogenic carbonates indicate a long-term shift toward regional drying or increased duration of the annual dry season through the early Pleistocene. This suggests that an annual dry season associated with monsoon conditions was an important aspect of the paleoclimate in which early humans spread from Africa to Southeast Asia.
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landscape development preceding Homo Erectus immigration into central java indonesia the sangiran formation lower lahar
Palaeogeography Palaeoclimatology Palaeoecology, 2004Co-Authors: Arthur E Bettis, Russell L Ciochon, Roy Larick, Mark K Reagan, Yahdi Zaim, Yan Rizal, Matthew T HeizlerAbstract:Abstract The Sangiran Dome is the primary stratigraphic window for the Solo Basin, a coastal feature on the Pliocene–Pleistocene Sunda subcontinent south margin. In the Dome, the Lower Lahar unit (LLU) is a lahar-type debris flow overlying near-shore marine sediments. The event that emplaced the LLU likely originated from sector collapse on a neighboring volcanic edifice. Freshwater mollusc fossils in the LLU indicate that swamps or shallow lakes lay between the edifice and the current Dome area. 40Ar/39Ar analyses on hornblende separates from six pumice lenses suggest that the LLU was deposited as early as 1.90±0.02 Ma. The event resulting in deposition of the LLU transformed late Pliocene near-shore marine environments into estuarine and marsh settings. Shortly thereafter, glacioeustatic sea level falls completed the local transition to fully terrestrial environments that attracted Homo Erectus to southernmost Sunda in the Early Pleistocene.
Yahdi Zaim - One of the best experts on this subject based on the ideXlab platform.
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last appearance of Homo Erectus at ngandong java 117 000 108 000 years ago
Nature, 2020Co-Authors: Yan Rizal, Arthur E Bettis, Rainer Grun, Yahdi Zaim, Kira E Westaway, Gerrit D Van Den Bergh, Michael J Morwood, Frank O Huffman, Renaud Joannesboyau, Richard M BaileyAbstract:Homo Erectus is the founding early hominin species of Island Southeast Asia, and reached Java (Indonesia) more than 1.5 million years ago1,2. Twelve H. Erectus calvaria (skull caps) and two tibiae (lower leg bones) were discovered from a bone bed located about 20 m above the Solo River at Ngandong (Central Java) between 1931 and 19333,4, and are of the youngest, most-advanced form of H. Erectus5–8. Despite the importance of the Ngandong fossils, the relationship between the fossils, terrace fill and ages have been heavily debated9–14. Here, to resolve the age of the Ngandong evidence, we use Bayesian modelling of 52 radiometric age estimates to establish—to our knowledge—the first robust chronology at regional, valley and local scales. We used uranium-series dating of speleothems to constrain regional landscape evolution; luminescence, 40argon/39argon (40Ar/39Ar) and uranium-series dating to constrain the sequence of terrace evolution; and applied uranium-series and uranium series–electron-spin resonance (US–ESR) dating to non-human fossils to directly date our re-excavation of Ngandong5,15. We show that at least by 500 thousand years ago (ka) the Solo River was diverted into the Kendeng Hills, and that it formed the Solo terrace sequence between 316 and 31 ka and the Ngandong terrace between about 140 and 92 ka. Non-human fossils recovered during the re-excavation of Ngandong date to between 109 and 106 ka (uranium-series minimum)16 and 134 and 118 ka (US–ESR), with modelled ages of 117 to 108 thousand years (kyr) for the H. Erectus bone bed, which accumulated during flood conditions3,17. These results negate the extreme ages that have been proposed for the site and solidify Ngandong as the last known occurrence of this long-lived species. Bayesian modelling of radiometric age estimates provides a robust chronology for Homo Erectus at Ngandong (Java), confirming that this site currently represents the last known occurrence of this species.
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new 1 5 million year old Homo Erectus maxilla from sangiran central java indonesia
Journal of Human Evolution, 2011Co-Authors: Yahdi Zaim, Russell L Ciochon, Arthur E Bettis, Roy Larick, Joshua M Polanski, Frederick E Grine, Yan Rizal, Robert G Franciscus, Matthew T Heizler, Lindsay K EavesAbstract:Sangiran (Solo Basin, Central Java, Indonesia) is the singular Homo Erectus fossil locale for Early Pleistocene Southeast Asia. Sangiran is the source for more than 80 specimens in deposits with 40 Ar/ 39 Ar ages of 1.51e0.9 Ma. In April 2001, we recovered a H. Erectus left maxilla fragment (preserving P 3 -M 2 ) from the Sangiran site of Bapang. The find spot lies at the base of the Bapang Formation type section in cemented gravelly sands traditionally called the Grenzbank Zone. Two meters above the find spot, pumice hornblende has produced an 40 Ar/ 39 Ar age of 1.51 � 0.08 Ma. With the addition of Bpg 2001.04,
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new reconstruction and morphological description of a Homo Erectus cranium skull ix tjg 1993 05 from sangiran central java
Journal of Human Evolution, 2011Co-Authors: Yousuke Kaifu, Hisao Baba, Yahdi Zaim, Yan Rizal, Iwan Kurniawan, Daisuke Kubo, Johan Arif, Fachroel AzizAbstract:Skull IX (Tjg-1993.05) was unearthed from the upper stratigraphic zone (Bapang-AG levels) of the hominin-bearing sequence in Sangiran. This remarkably complete cranial specimen of Homo Erectus from the early Pleistocene of Java preserves substantial portions of the vault and face. However, the distortion present in the original reconstruction has hampered detailed documentation of its morphological characteristics. We here report a new reconstruction of Skull IX that successfully recovers the original morphology and significantly differs from previous reconstructions. Detailed morphological description and the results of initial comparative analyses based on this new reconstruction are provided. The endocranial volume of Skull IX was measured as 870 cc using micro-CT data. The neurocranium of Skull IX is slightly smaller than the so far recorded smallest cranium from this zone, suggesting this individual was female. In most, but not all, aspects of the cranial vault form, details of the external surface structures, and facial morphology, Skull IX exhibits numerous similarities to the other Bapang-AG H. Erectus specimens, indicating that it belonged to the Bapang-AG H. Erectus population. Drawing on the expanded fossil sample of this chronoregional H. Erectus group, we discuss their evolutionary status, degree of sexual dimorphism, and facial morphological variation in Afro-Asian earlier Homo specimens.
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way out of africa early pleistocene paleoenvironments inhabited by Homo Erectus in sangiran java
Journal of Human Evolution, 2009Co-Authors: Arthur E Bettis, Russell L Ciochon, Roy Larick, Yahdi Zaim, Yan Rizal, Adrianne K Milius, Scott J Carpenter, Stephanie Tassiersurine, Daniel Murray, Sutinko BrontoAbstract:A sequence of paleosols in the Solo Basin, Central Java, Indonesia, documents the local and regional environments present when Homo Erectus spread through Southeast Asia during the early Pleistocene. The earliest human immigrants encountered a low-relief lake-margin landscape dominated by moist grasslands with open woodlands in the driest landscape positions. By 1.5 Ma, large streams filled the lake and the landscape became more riverine in nature, with riparian forests, savanna, and open woodland. Paleosol morphology and carbon isotope values of soil organic matter and pedogenic carbonates indicate a long-term shift toward regional drying or increased duration of the annual dry season through the early Pleistocene. This suggests that an annual dry season associated with monsoon conditions was an important aspect of the paleoclimate in which early humans spread from Africa to Southeast Asia.
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landscape development preceding Homo Erectus immigration into central java indonesia the sangiran formation lower lahar
Palaeogeography Palaeoclimatology Palaeoecology, 2004Co-Authors: Arthur E Bettis, Russell L Ciochon, Roy Larick, Mark K Reagan, Yahdi Zaim, Yan Rizal, Matthew T HeizlerAbstract:Abstract The Sangiran Dome is the primary stratigraphic window for the Solo Basin, a coastal feature on the Pliocene–Pleistocene Sunda subcontinent south margin. In the Dome, the Lower Lahar unit (LLU) is a lahar-type debris flow overlying near-shore marine sediments. The event that emplaced the LLU likely originated from sector collapse on a neighboring volcanic edifice. Freshwater mollusc fossils in the LLU indicate that swamps or shallow lakes lay between the edifice and the current Dome area. 40Ar/39Ar analyses on hornblende separates from six pumice lenses suggest that the LLU was deposited as early as 1.90±0.02 Ma. The event resulting in deposition of the LLU transformed late Pliocene near-shore marine environments into estuarine and marsh settings. Shortly thereafter, glacioeustatic sea level falls completed the local transition to fully terrestrial environments that attracted Homo Erectus to southernmost Sunda in the Early Pleistocene.