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Frost SR, Jablonski NG, Haile-Selassie Y. The earliest most complete skeleton of Theropithecus. J Hum Evol 2023; 180:103370. [PMID: 37167814 DOI: 10.1016/j.jhevol.2023.103370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 03/30/2023] [Accepted: 03/30/2023] [Indexed: 05/13/2023]
Abstract
The middle Pliocene site of Woranso-Mille in the Afar Region of Ethiopia has yielded numerous significant early hominin fossils representing multiple, coexisting taxa. Here we report on another significant discovery, the oldest partial skeleton of the papionin, Theropithecus. The specimen was recovered from the Aralee Issie collection area over multiple field seasons from 2004 through 2019. The specimen was unearthed in situ from the fluvial facies of the Mesgid Dora Tuff dated to 3.66-3.57 Ma. The partial skeleton, ARI-VP-1/26, is that of a subadult male lacking a skull. In the absence of unambiguously associated craniodental remains, the male status of the specimen was established from the dimensions of the long bones in comparison to those of other Theropithecus from Woranso-Mille. ARI-VP-1/26 is noteworthy because it preserves partial hand and foot skeletons, including a complete set of metacarpals from the left side. The theropith status of ARI-VP-1/26 was established based on the detailed anatomy of the postcranial skeleton, especially the proximal and distal humerus, proximal radius, and proximal femur. The morphology of the postcranium of ARI-VP-1/26 is consistent with that of recognized Theropithecus from Woranso-Mille and, specifically, with specimens recognized as Theropithecus oswaldi cf. darti from other sites. The ratio of the lengths of the first metacarpal to metacarpals 2-5 in ARI-VP-1/26 is intermediate between that seen in extant Papio and Theropithecus. In Theropithecus gelada and Theropithecus brumpti, the pairing of pollical and indical metacarpals of near equal length contributes to the species' high opposability index and is associated with a 'manual grazing' feeding habit. Cercopithecids constitute 43% of the identified vertebrates at Aralee Issie, and T. oswaldi cf. darti is the most common mammalian species. The monkeys of Aralee Issie lived in an open shrubland habitat, but the specific reasons for their high prevalence at the site are unclear.
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Affiliation(s)
- Stephen R Frost
- Department of Anthropology, University of Oregon, Eugene, OR 97403-1218, USA.
| | - Nina G Jablonski
- Department of Anthropology, The Pennsylvania State University, 409 Carpenter Building, University Park, PA 16802, USA
| | - Yohannes Haile-Selassie
- Institute of Human Origins, School of Human Evolution and Social Change, Arizona State University, Tempe, AZ 85281, USA
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2
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Alemseged Z. Reappraising the palaeobiology of Australopithecus. Nature 2023; 617:45-54. [PMID: 37138108 DOI: 10.1038/s41586-023-05957-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 03/14/2023] [Indexed: 05/05/2023]
Abstract
The naming of Australopithecus africanus in 1925, based on the Taung Child, heralded a new era in human evolutionary studies and turned the attention of the then Eurasian-centric palaeoanthropologists to Africa, albeit with reluctance. Almost one hundred years later, Africa is recognized as the cradle of humanity, where the entire evolutionary history of our lineage prior to two million years ago took place-after the Homo-Pan split. This Review examines data from diverse sources and offers a revised depiction of the genus and characterizes its role in human evolution. For a long time, our knowledge of Australopithecus came from both A. africanus and Australopithecus afarensis, and the members of this genus were portrayed as bipedal creatures that did not use stone tools, with a largely chimpanzee-like cranium, a prognathic face and a brain slightly larger than that of chimpanzees. Subsequent field and laboratory discoveries, however, have altered this portrayal, showing that Australopithecus species were habitual bipeds but also practised arboreality; that they occasionally used stone tools to supplement their diet with animal resources; and that their infants probably depended on adults to a greater extent than what is seen in apes. The genus gave rise to several taxa, including Homo, but its direct ancestor remains elusive. In sum, Australopithecus had a pivotal bridging role in our evolutionary history owing to its morphological, behavioural and temporal placement between the earliest archaic putative hominins and later hominins-including the genus Homo.
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Comparative description and taxonomic affinity of 3.7-million-year-old hominin mandibles from Woranso-Mille (Ethiopia). J Hum Evol 2022; 173:103265. [PMID: 36306541 DOI: 10.1016/j.jhevol.2022.103265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 09/02/2022] [Accepted: 09/02/2022] [Indexed: 11/06/2022]
Abstract
Fossil discoveries of early Australopithecus species from Woranso-Mille have played a significant role in improving our understanding of mid-Pliocene hominin evolution and diversity. Here, we describe two mandibles with dentitions, recovered from sediments immediately above a tuff radiometrically dated to 3.76 ± 0.02 Ma, and assess their taxonomic affinity. The two mandibles (MSD-VP-5/16 and MSD-VP-5/50) show morphological similarities with both Australopithecus anamensis and Australopithecus afarensis. Some of the unique features that distinguish Au. anamensis from Au. afarensis are present in the mandibles, which also share a few derived features with Au. afarensis. Their retention of more Kanapoi Au. anamensis-like traits, compared to the fewer derived features they share with Au. afarensis, and the presence of Au. anamensis at Woranso-Mille in 3.8-million-year-old deposits, lends support to their assignment to Au. anamensis. However, it is equally arguable that the few derived dentognathic features they share with Au. afarensis could be taxonomically more significant, making it difficult to conclusively assign these specimens to either species. Regardless of which species they are assigned to, the mosaic nature of the dentognathic morphology and geological age of the two mandibles lends further support to the hypothesized ancestor-descendant relationship between Au. anamensis and Au. afarensis. However, there is now limited fossil evidence indicating that these two species may have overlapped in time. Hence, the last appearance of Au. anamensis and first appearance of Au. afarensis are currently unknown. Recovery of Australopithecus fossils from 4.1 to 3.8 Ma is critical to further address the timing of these events.
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Pérez-Claros JA, Palmqvist P. Heterochronies and allometries in the evolution of the hominid cranium: a morphometric approach using classical anthropometric variables. PeerJ 2022; 10:e13991. [PMID: 36042865 PMCID: PMC9420405 DOI: 10.7717/peerj.13991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 08/11/2022] [Indexed: 01/19/2023] Open
Abstract
This article studies the evolutionary change of allometries in the relative size of the two main cranial modules (neurocranium and splanchnocranium) in the five living hominid species and a diverse sample of extinct hominins. We use six standard craniometric variables as proxies for the length, width and height of each cranial module. Factor analysis and two-block partial least squares (2B-PLS) show that the great apes and modern humans share a pervasive negative ontogenetic allometry in the neurocranium and a positive one in the splanchnocranium. This developmental constraint makes it possible to interpret the cranial heterochronies in terms of ontogenetic scaling processes (i.e., extensions or truncations of the ancestral ontogenetic trajectory) and lateral transpositions (i.e., parallel translations of the entire trajectory starting from a different shape for a given cranial size). We hypothesize that ontogenetic scaling is the main evolutionary modality in the australopithecines while in the species of Homo it is also necessary to apply transpositions. Both types of processes are coordinated in Homo, which result in an evolutionary trend toward an increase in brain size and in the degree of paedomorphosis from the earliest habilines.
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Mosaic habitats at Woranso-Mille (Ethiopia) during the Pliocene and implications for Australopithecus paleoecology and taxonomic diversity. J Hum Evol 2022; 163:103076. [PMID: 34998271 DOI: 10.1016/j.jhevol.2021.103076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 08/27/2021] [Accepted: 08/27/2021] [Indexed: 11/21/2022]
Abstract
Many important Pliocene hominin specimens have been recovered from Woranso-Mille, a paleontological research area in the Afar region of Ethiopia, including the complete cranium of Australopithecus anamensis, a partial skeleton of Australopithecus afarensis, mandibular and maxillary elements representing a new species, Australopithecus deyiremeda, and a partial foot of an as-yet-unnamed species. Woranso-Mille is the only site, so far, to have reported the co-existence of more than one early hominin species between 3.8 and 3.3 Ma and the temporal overlap between A. anamensis and A. afarensis. Thus, the site has important implications for our understanding of the paleoecology and taxonomic diversity of early hominins and their ecological niche. This paper explores the paleohabitats of Woranso-Mille through its faunal community ecological structure and taxonomic composition using correspondence analysis and Forbes modified similarity index. The results suggest that Pliocene Woranso-Mille was a mosaic of different habitat types, with riparian woodland and floodplain grassland along rivers draining into a lake, along with less mesic habitats such as woodland, grassland, and shrubland. The apparent high level of vegetation heterogeneity may have promoted dietary specializations and niche differentiation among the different Australopithecus species at Woranso-Mille and allowed for their co-existence at the site.
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Haile-Selassie Y. From Trees to the Ground: The Significance of Australopithecus anamensis in Human Evolution. JOURNAL OF ANTHROPOLOGICAL RESEARCH 2021. [DOI: 10.1086/716743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Melillo SM, Gibert L, Saylor BZ, Deino A, Alene M, Ryan TM, Haile-Selassie Y. New Pliocene hominin remains from the Leado Dido'a area of Woranso-Mille, Ethiopia. J Hum Evol 2021; 153:102956. [PMID: 33711722 DOI: 10.1016/j.jhevol.2021.102956] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 01/25/2021] [Accepted: 01/25/2021] [Indexed: 10/22/2022]
Abstract
Fossiliferous deposits at Woranso-Mille span the period when Australopithecus anamensis gave rise to Australopithecus afarensis (3.8-3.6 Ma) and encompass the core of the A. afarensis range (ca. 3.5-3.2 Ma). Within the latter period, fossils described to date include the intriguing but taxonomically unattributed Burtele foot, dentognathic fossils attributed to Australopithecus deyiremeda, and one specimen securely attributed to A. afarensis (the Nefuraytu mandible). These fossils suggest that at least one additional hominin lineage lived alongside A. afarensis in the Afar Depression. Here we describe a collection of hominin fossils from a new locality in the Leado Dido'a area of Woranso-Mille (LDD-VP-1). The strata in this area are correlated to the same chron as those in the Burtele area (C2An.3n; 3.59-3.33 Ma), and similar in age to the Maka Sands and the Basal through lower Sidi Hakoma Members of the Hadar Formation. We attribute all but one of the LDD hominin specimens to A. afarensis, based on diagnostic morphology of the mandible, maxilla, canines, and premolars. The LDD specimens generally fall within the range of variation previously documented for A. afarensis but increase the frequency of some rare morphological variants. However, one isolated M3 is extremely small, and its taxonomic affinity is currently unknown. The new observations support previous work on temporal trends in A. afarensis and demonstrate that the large range of variation accepted for this species is present even within a limited spatiotemporal range. The value added with this sample lies in its contribution to controlling for spatiotemporal differences among site samples in the A. afarensis hypodigm and its contemporaneity with non-A. afarensis specimens at Woranso-Mille.
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Affiliation(s)
- Stephanie M Melillo
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology Leipzig, Germany.
| | - Luis Gibert
- Departament de Mineralogia, Petrologia i Geologia Aplicada Facultat de Ciències de la Terra, Universitat de Barcelona, Barcelona, Spain
| | - Beverly Z Saylor
- Department of Earth, Environmental and Planetary Sciences, Case Western Reserve University, Cleveland, OH, USA
| | - Alan Deino
- Berkeley Geochronology Center, Berkeley, CA, USA
| | - Mulugeta Alene
- School of Earth Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Timothy M Ryan
- Department of Anthropology, Pennsylvania State University, University Park, PA, USA
| | - Yohannes Haile-Selassie
- Department of Physical Anthropology, Cleveland Museum of Natural History, Cleveland, OH, USA; Departments of Anthropology and Biology, Case Western Reserve University, Cleveland, OH, USA
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8
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Skinner MM, Leakey MG, Leakey LN, Manthi FK, Spoor F. Hominin dental remains from the Pliocene localities at Lomekwi, Kenya (1982-2009). J Hum Evol 2020; 145:102820. [PMID: 32593871 DOI: 10.1016/j.jhevol.2020.102820] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 04/26/2020] [Accepted: 04/26/2020] [Indexed: 10/24/2022]
Abstract
Increasing evidence for both taxonomic diversity and early stone manufacture during the Pliocene highlights the importance of the hominin fossil record from this epoch in eastern Africa. Here, we describe dental remains from Lomekwi (West Turkana, Kenya), which date from between 3.2 and 3.5 Ma. The sample was collected between 1982 and 2009 and includes five gnathic specimens and a total of 67 teeth (mostly isolated permanent postcanine teeth). Standard linear dimensions indicate that, although the Lomekwi teeth are relatively small, there is broad overlap in size with contemporary Australopithecus afarensis and Australopithecus deyiremeda specimens at most tooth positions. However, some dental characters differentiate this sample from these species, including a relatively large P4 and M3 compared with the M1, a high incidence of well-developed protostylids, and specific accessory molar cuspules. Owing to a lack of well-preserved tooth crowns (and the complete absence of mandibular teeth) in the holotype and paratype of Kenyanthropus platyops, and limited comparable gnathic morphology in the new specimens, it cannot be determined whether these Lomekwi specimens should be attributed to this species. Attribution of these specimens is further complicated by a lack of certainty about position along the tooth row of many of the molar specimens. More comprehensive shape analyses of the external and internal morphology of these specimens, and additional fossil finds, would facilitate the taxonomic attribution of specimens in this taxonomically diverse period of human evolution.
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Affiliation(s)
- Matthew M Skinner
- School of Anthropology and Conservation, University of Kent, Canterbury, CT2 7NR, UK; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, 04103, Germany.
| | - Meave G Leakey
- Turkana Basin Institute, PO Box 24926, Nairobi, 00502, Kenya; Department of Anthropology, Stony Brook University, Stony Brook, 11794, USA
| | - Louise N Leakey
- Turkana Basin Institute, PO Box 24926, Nairobi, 00502, Kenya; Department of Anthropology, Stony Brook University, Stony Brook, 11794, USA
| | - Fredrick K Manthi
- Department of Earth Sciences, National Museums of Kenya, Nairobi, Kenya
| | - Fred Spoor
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, 04103, Germany; Centre for Human Evolution Research, Department of Earth Sciences, The Natural History Museum, London, SW7 5BD, UK; Department of Anthropology, University College London, WC1E 6BT, UK.
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9
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New fossils of Australopithecus anamensis from Kanapoi, West Turkana, Kenya (2012–2015). J Hum Evol 2020; 140:102368. [DOI: 10.1016/j.jhevol.2017.07.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 07/12/2017] [Accepted: 07/12/2017] [Indexed: 11/16/2022]
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10
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Pitirri MK, Begun D. Ontogenetic insights into the significance of mandibular corpus shape variation in hominoids: Developmental covariation between M 2 crypt formation and corpus shape. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2019; 171:76-88. [PMID: 31710703 DOI: 10.1002/ajpa.23969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 10/18/2019] [Accepted: 10/27/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVES Here, we quantify and compare the cross-sectional shape of the mandibular corpus between M1 and M2 during growth in Pan paniscus, Pan troglodytes, and Pongo pygmaeus. The goal is to assess the hypothesis that the shape of the corpus is influenced by the development of permanent molars in their crypts, by examining ontogenetic changes in corpus shape and investigating covariation between corpus shape and M2 and M3 molar crypt forms. MATERIALS AND METHODS Ontogenetic changes in mandibular corpus shape were assessed using landmarks and semilandmarks, and measurements of length, width, and height were used to quantify molar crypts (M2 and M3 ). Ontogenetic changes in corpus growth from the eruption of M1 to the eruption of M3 were evaluated for each species through generalized Procrustes analysis and principal components analysis in shape-space and form-space. The relationship between corpus shape and molar crypt form was investigated at three different developmental stages using two-block partial least squares (2B-PLS) analysis. RESULTS The results show clear differences in growth patterns among all three species and provide evidence that species-level differences in mandibular corpus growth occur prior to the emergence of M1 . The results of the 2B-PLS analysis reveal that significant covariance between corpus shape and molar crypt form is limited to the developmental stage marked by the emergence of M1 , with covariance between corpus shape and M2 crypt width. Corpora that are relatively narrower in the inferior portion of the cross section covary with relatively narrower M2 crypts. CONCLUSIONS These results have important implications for understanding the taxonomic and phylogenetic significance of mandibular corpus shape variation in the hominoid fossil record.
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Affiliation(s)
- M K Pitirri
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania.,Department of Anthropology, University of Toronto, Toronto, Ontario
| | - David Begun
- Department of Anthropology, University of Toronto, Toronto, Ontario
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Haile-Selassie Y, Melillo SM, Vazzana A, Benazzi S, Ryan TM. A 3.8-million-year-old hominin cranium from Woranso-Mille, Ethiopia. Nature 2019; 573:214-219. [DOI: 10.1038/s41586-019-1513-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 08/01/2019] [Indexed: 11/09/2022]
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Davies TW, Delezene LK, Gunz P, Hublin JJ, Skinner MM. Endostructural morphology in hominoid mandibular third premolars: Geometric morphometric analysis of dentine crown shape. J Hum Evol 2019; 133:198-213. [PMID: 31358180 DOI: 10.1016/j.jhevol.2019.06.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 06/19/2019] [Accepted: 06/19/2019] [Indexed: 01/17/2023]
Abstract
In apes, the mandibular third premolar (P3) is adapted for a role in honing the large upper canine. The role of honing was lost early in hominin evolution, releasing the tooth from this functional constraint and allowing it to respond to subsequent changes in masticatory demands. This led to substantial morphological changes, and as such the P3 has featured prominently in systematic analyses of the hominin clade. The application of microtomography has also demonstrated that examination of the enamel-dentine junction (EDJ) increases the taxonomic value of variations in crown morphology. Here we use geometric morphometric techniques to analyze the shape of the P3 EDJ in a broad sample of fossil hominins, modern humans, and extant apes (n = 111). We test the utility of P3 EDJ shape for distinguishing among hominoids, address the affinities of a number of hominin specimens of uncertain taxonomic attribution, and characterize the changes in P3 EDJ morphology across our sample, with particular reference to features relating to canine honing and premolar 'molarization'. We find that the morphology of the P3 EDJ is useful in taxonomic identification of individual specimens, with a classification accuracy of up to 88%. The P3 EDJ of canine-honing apes displays a tall protoconid, little metaconid development, and an asymmetrical crown shape. Plio-Pleistocene hominin taxa display derived masticatory adaptations at the EDJ, such as the molarized premolars of Australopithecus africanus and Paranthropus, which have well-developed marginal ridges, an enlarged talonid, and a large metaconid. Modern humans and Neanderthals display a tall dentine body and reduced metaconid development, a morphology shared with premolars from Mauer and the Cave of Hearths. Homo naledi displays a P3 EDJ morphology that is unique among our sample; it is quite unlike Middle Pleistocene and recent Homo samples and most closely resembles Australopithecus, Paranthropus and early Homo specimens.
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Affiliation(s)
- Thomas W Davies
- School of Anthropology and Conservation, University of Kent, Canterbury, CT2 7NZ, UK; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany.
| | - Lucas K Delezene
- Department of Anthropology, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Philipp Gunz
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Jean-Jacques Hublin
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Matthew M Skinner
- School of Anthropology and Conservation, University of Kent, Canterbury, CT2 7NZ, UK; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
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Haile-Selassie Y, Ryan TM. Comparative description and taxonomy of new hominin juvenile mandibles from the Pliocene of Woranso-Mille (Central Afar, Ethiopia). J Hum Evol 2019; 132:15-31. [DOI: 10.1016/j.jhevol.2019.04.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 04/13/2019] [Accepted: 04/15/2019] [Indexed: 12/01/2022]
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14
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Joordens JC, Feibel CS, Vonhof HB, Schulp AS, Kroon D. Relevance of the eastern African coastal forest for early hominin biogeography. J Hum Evol 2019; 131:176-202. [DOI: 10.1016/j.jhevol.2019.03.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 03/10/2019] [Accepted: 03/13/2019] [Indexed: 12/25/2022]
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15
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Meyer MR, Williams SA. Earliest axial fossils from the genus Australopithecus. J Hum Evol 2019; 132:189-214. [PMID: 31203847 DOI: 10.1016/j.jhevol.2019.05.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 05/05/2019] [Accepted: 05/06/2019] [Indexed: 11/19/2022]
Abstract
Australopitheus anamensis fossils demonstrate that craniodentally and postcranially the taxon was more primitive than its evolutionary successor Australopithecus afarensis. Postcranial evidence suggests habitual bipedality combined with primitive upper limbs and an inferred significant arboreal adaptation. Here we report on A. anamensis fossils from the Assa Issie locality in Ethiopia's Middle Awash area dated to ∼4.2 Ma, constituting the oldest known Australopithecus axial remains. Because the spine is the interface between major body segments, these fossils can be informative on the adaptation, behavior and our evolutionary understanding of A. anamensis. The atlas, or first cervical vertebra (C1), is similar in size to Homo sapiens, with synapomorphies in the articular facets and transverse processes. Absence of a retroglenoid tubercle suggests that, like humans, A. anamensis lacked the atlantoclavicularis muscle, resulting in reduced capacity for climbing relative to the great apes. The retroflexed C2 odontoid process and long C6 spinous process are reciprocates of facial prognathism, a long clivus and retroflexed foramen magnum, rather than indications of locomotor or postural behaviors. The T1 is derived in shape and size as in Homo with an enlarged vertebral body epiphyseal surfaces for mitigating the high-magnitude compressive loads of full-time bipedality. The full costal facet is unlike the extant great ape demifacet pattern and represents the oldest evidence for the derived univertebral pattern in hominins. These fossils augment other lines of evidence in A. anamensis indicating habitual bipedality despite some plesiomorphic vertebral traits related to craniofacial morphology independent of locomotor or postural behaviors (i.e., a long clivus and a retroflexed foramen magnum). Yet in contrast to craniodental lines of evidence, some aspects of vertebral morphology in A. anamensis appear more derived than its descendant A. afarensis.
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Affiliation(s)
- Marc R Meyer
- Department of Anthropology, Chaffey College, Rancho Cucamonga, CA, 91737, USA.
| | - Scott A Williams
- Center for the Study of Human Origins, Department of Anthropology, New York University, 25 Waverly Place, New York, NY, 10003, USA; New York Consortium in Evolutionary Primatology, New York, NY, 10024, USA
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16
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Pitirri MK, Begun D. A new method to quantify mandibular corpus shape in extant great apes and its potential application to the hominoid fossil record. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 168:318-328. [PMID: 30537105 DOI: 10.1002/ajpa.23749] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 10/08/2018] [Accepted: 10/20/2018] [Indexed: 11/10/2022]
Abstract
OBJECTIVES Mandibular corpus robusticity (corpus breadth/corpus height) is the most commonly utilized descriptor of the mandibular corpus in the great ape and hominin fossil records. As a consequence of its contoured shape, linear metrics used to characterize mandibular robusticity are inadequate to quantify the shape of the mandibular corpus. Here, we present an alternative to the traditional assessment of mandibular shape by analyzing the outline of the mandibular corpus in cross-section using landmarks and semilandmarks. MATERIALS AND METHODS Outlines of the mandibular corpus in cross-section between M1 and M2 were quantified in a sample of hominoids and analyzed using generalized Procrustes analysis, Procrustes ANOVA, CVA, and cluster analysis. Corpus breadth and width were also collected from the same sample and analyzed using regression, ANOVA, and cluster analysis. RESULTS Analysis of corpus outline shape revealed significant differences in mandibular corpus shape that are independent of size and sex at the genus level across hominoids. Cluster analysis based on the analysis of corpus outline shape results in almost all specimens grouping based on taxonomic affinity (99.28% correct classification). Comparison of these results to results using traditional measures of mandibular robusticity shows that analysis of the outline of the corpus in cross-section discriminate extant great apes more reliably. CONCLUSION The strong taxonomic signal revealed by this analysis indicates that quantification of the outline of the mandibular corpus more fully captures mandibular corpus shape and offers the potential for greater power in discriminating among taxa in the hominoid fossil record.
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Affiliation(s)
- M Kathleen Pitirri
- Department of Anthropology, Pennsylvania State University, Pennsylvania.,Department of Anthropology, University of Toronto, St. Toronto, Ontario, Canada
| | - David Begun
- Department of Anthropology, University of Toronto, St. Toronto, Ontario, Canada
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The Pliocene hominin diversity conundrum: Do more fossils mean less clarity? Proc Natl Acad Sci U S A 2017; 113:6364-71. [PMID: 27274043 DOI: 10.1073/pnas.1521266113] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recent discoveries of multiple middle Pliocene hominins have raised the possibility that early hominins were as speciose as later hominins. However, debates continue to arise around the validity of most of these new taxa, largely based on poor preservation of holotype specimens, small sample size, or the lack of evidence for ecological diversity. A closer look at the currently available fossil evidence from Ethiopia, Kenya, and Chad indicate that Australopithecus afarensis was not the only hominin species during the middle Pliocene, and that there were other species clearly distinguishable from it by their locomotor adaptation and diet. Although there is no doubt that the presence of multiple species during the middle Pliocene opens new windows into our evolutionary past, it also complicates our understanding of early hominin taxonomy and phylogenetic relationships.
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Haile-Selassie Y, Melillo SM, Ryan TM, Levin NE, Saylor BZ, Deino A, Mundil R, Scott G, Mulugeta Alene, Gibert L. Dentognathic remains of Australopithecus afarensis from Nefuraytu (Woranso-Mille, Ethiopia): Comparative description, geology, and paleoecological context. J Hum Evol 2016; 100:35-53. [DOI: 10.1016/j.jhevol.2016.08.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Revised: 08/03/2016] [Accepted: 08/03/2016] [Indexed: 11/30/2022]
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Curran SC, Haile-Selassie Y. Paleoecological reconstruction of hominin-bearing middle Pliocene localities at Woranso-Mille, Ethiopia. J Hum Evol 2016; 96:97-112. [DOI: 10.1016/j.jhevol.2016.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 04/14/2016] [Accepted: 04/16/2016] [Indexed: 10/21/2022]
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Saylor BZ, Angelini J, Deino A, Alene M, Fournelle JH, Haile-Selassie Y. Tephrostratigraphy of the Waki-Mille area of the Woranso-Mille paleoanthropological research project, Afar, Ethiopia. J Hum Evol 2016; 93:25-45. [DOI: 10.1016/j.jhevol.2015.12.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 12/10/2015] [Accepted: 12/31/2015] [Indexed: 11/30/2022]
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Abstract
Australopithecus bahrelghazali, its origin and palaeobiology are not well understood. Reported from only one location some several thousand kilometres away from East African Pliocene hominin sites, it appears to have predominantly fed on C4 sources. Yet, it lacks the morphological adaptations of other primate C4 consumers like Paranthropus boisei and Theropithecus oswaldi. Furthermore, although considered to belong to Australopithecus afarensis by most researchers, A. bahrelghazali appears to differ from the former in a key aspect of its morphology: enamel thickness. To assess the phylogeny and palaeobiology of A. bahrelghazali, I first evaluate the dietary adaptations and energetics of A. bahrelghazali using empirical data of the feeding ecology of extant baboons, Papio cynocephalus. Information published on A. bahrelghazali morphology and habitat preference is used to select C4 foods with the appropriate mechanical properties and availability within the environment to create the models. By altering the feeding time on various food categories, I then test whether A. bahrelghazali could have subsisted on a C4 diet, thus accounting for the δ(13)C composition of its dental tissue. The effects of body mass on the volume of food consumed are taken into account. The outcomes of these simulations indicate that A. bahrelghazali could have subsisted on a diet of predominantly sedges, albeit with limitations. At higher energy requirements, i.e., above 3.5 times the BMR, it would be difficult for a medium-sized primate to obtain sufficient energy from a sedge-based diet. This is apparently due to constraints on foraging/feeding time, not because of the nutritional value of sedges per se. These results are discussed against the backdrop of A. bahrelghazali biogeography, palaeoenvironment, and phylogeny. The combined evidence makes it plausible to suggest that Northern Chad may have been a refugium for migrating mammals, including hominins, and throws new light on the deep history of A. bahrelghazali.
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Haile-Selassie Y, Melillo SM. Middle Pliocene hominin mandibular fourth premolars from Woranso-Mille (Central Afar, Ethiopia). J Hum Evol 2015; 78:44-59. [DOI: 10.1016/j.jhevol.2014.08.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 08/11/2014] [Accepted: 08/11/2014] [Indexed: 11/16/2022]
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New fossils of Australopithecus anamensis from Kanapoi, West Turkana, Kenya (2003–2008). J Hum Evol 2013; 65:501-24. [DOI: 10.1016/j.jhevol.2013.05.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 05/06/2013] [Accepted: 05/07/2013] [Indexed: 11/22/2022]
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Diet of Australopithecus afarensis from the Pliocene Hadar Formation, Ethiopia. Proc Natl Acad Sci U S A 2013; 110:10495-500. [PMID: 23733965 DOI: 10.1073/pnas.1222559110] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The enhanced dietary flexibility of early hominins to include consumption of C4/crassulacean acid metabolism (CAM) foods (i.e., foods derived from grasses, sedges, and succulents common in tropical savannas and deserts) likely represents a significant ecological and behavioral distinction from both extant great apes and the last common ancestor that we shared with great apes. Here, we use stable carbon isotopic data from 20 samples of Australopithecus afarensis from Hadar and Dikika, Ethiopia (>3.4-2.9 Ma) to show that this species consumed a diet with significant C4/CAM foods, differing from its putative ancestor Au. anamensis. Furthermore, there is no temporal trend in the amount of C4/CAM food consumption over the age of the samples analyzed, and the amount of C4/CAM food intake was highly variable, even within a single narrow stratigraphic interval. As such, Au. afarensis was a key participant in the C4/CAM dietary expansion by early australopiths of the middle Pliocene. The middle Pliocene expansion of the eastern African australopith diet to include savanna-based foods represents a shift to use of plant food resources that were already abundant in hominin environments for at least 1 million y and sets the stage for dietary differentiation and niche specialization by subsequent hominin taxa.
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Molar Microwear, Diet and Adaptation in a Purported Hominin Species Lineage from the Pliocene of East Africa. THE PALEOBIOLOGY OF AUSTRALOPITHECUS 2013. [DOI: 10.1007/978-94-007-5919-0_14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Lacruz RS, Ramirez Rozzi FV, Wood BA, Bromage TG. Brief Communication: Molar development and crown areas in earlyAustralopithecus. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2012; 148:632-40. [DOI: 10.1002/ajpa.22089] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 04/09/2012] [Indexed: 11/12/2022]
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Grine FE, Sponheimer M, Ungar PS, Lee-Thorp J, Teaford MF. Dental microwear and stable isotopes inform the paleoecology of extinct hominins. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2012; 148:285-317. [DOI: 10.1002/ajpa.22086] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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A new hominin foot from Ethiopia shows multiple Pliocene bipedal adaptations. Nature 2012; 483:565-9. [DOI: 10.1038/nature10922] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2011] [Accepted: 02/08/2012] [Indexed: 11/08/2022]
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Sanders WJ, Haile-Selassie Y. A New Assemblage of Mid-Pliocene Proboscideans from the Woranso-Mille Area, Afar Region, Ethiopia: Taxonomic, Evolutionary, and Paleoecological Considerations. J MAMM EVOL 2011. [DOI: 10.1007/s10914-011-9181-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Delezene LK, Kimbel WH. Evolution of the mandibular third premolar crown in early Australopithecus. J Hum Evol 2011; 60:711-30. [DOI: 10.1016/j.jhevol.2011.01.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Revised: 12/30/2010] [Accepted: 01/08/2011] [Indexed: 10/18/2022]
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Ward CV, Plavcan JM, Manthi FK. Anterior dental evolution in the Australopithecus anamensis-afarensis lineage. Philos Trans R Soc Lond B Biol Sci 2010; 365:3333-44. [PMID: 20855307 PMCID: PMC2981954 DOI: 10.1098/rstb.2010.0039] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Australopithecus anamensis is the earliest known species of the Australopithecus-human clade and is the likely ancestor of Australopithecus afarensis. Investigating possible selective pressures underlying these changes is key to understanding the patterns of selection shaping the origins and early evolution of the Australopithecus-human clade. During the course of the Au. anamensis-afarensis lineage, significant changes appear to occur particularly in the anterior dentition, but also in jaw structure and molar form, suggesting selection for altered diet and/or food processing. Specifically, canine tooth crown height does not change, but maxillary canines and P(3)s become shorter mesiodistally, canine tooth crowns become more symmetrical in profile and P(3)s less unicuspid. Canine roots diminish in size and dimorphism, especially relative to the size of the postcanine teeth. Molar crowns become higher. Tooth rows become more divergent and symphyseal form changes. Dietary change involving anterior dental use is also suggested by less intense anterior tooth wear in Au. afarensis. These dental changes signal selection for altered dietary behaviour and explain some differences in craniofacial form between these taxa. These data identify Au. anamensis not just as a more primitive version of Au. afarensis, but as a dynamic member of an evolving lineage leading to Au. afarensis, and raise intriguing questions about what other evolutionary changes occurred during the early evolution of the Australopithecus-human clade, and what characterized the origins of the group.
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Affiliation(s)
- Carol V Ward
- Department of Pathology and Anatomical Sciences, University of Missouri, M263 Medical Sciences Building, Columbia, MO 65212, USA.
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