ARTICLE RESEARCH Burtele(BRT) 2.Deino,A.Letal.40Ar/39Ar dating paleomagnetism,and tephrochemistry of Soil Pliocene strata of the hominid-bearing Woranso-Mille area,west-central Afar Rift. 30 Ethiopia.J.Hum.Evol.58,111-126(2010). .n ..Pebbly sandstone Haile-Selassie,Y.,Saylor,B.Z,Deino,A.,Alene,M.&Latimer,B.New hominid fossils a Coarse sandstone from Woranso-Mille(Central Afar,Ethiopia)the taxonomy ofearly Australopithecus. Am.J.Phys.Anthropol.141,406-417(2009). 4 ▣ Flaggy sandstone 4. Haile-Selassie,Y.et al.An early Australopithecus afarensis postcranium from Woranso-Mille,Ethiopia.Proc.Nat/Acad.Sci.USA 107,12121-12126(2010) 5. Haile-Selassie,Y.Phylogeny of early Australopithecus:new fossil evidence from the WM11-BRT-141 口 Mudstone and sandstone Woranso-Mille (Central Afar,Ethiopia).Phil Trans.R.Soc.B 365,3323-3331 bbb Basalt (2010). 6. Latimer,B.M.Lovejoy,C.O.Hominid tarsal,metatarsal,and phalangeal bones 20 ⊙ Gastropod layer recovered from the e Ha ar formation:1974-1977 collections.Am.J.Phys. Anthropol.57,701-719(1982). Planar laminations 1 Day,M.H.Napier,J.R.Hominid fossils from Bed l,Olduvai Gorge,Tanganyika: PL. Parting lineations fossil footbones.Nature 201,969-970 (1964). 三P Zipfel,B.et al.The foot and ankle of Australopithecus sediba.Science 333, Ripple stratification 1417-1420(2011) WM11-BRT-140 9. Clarke.R.J.Tobias.P.V.Sterkfontein Member 2 foot bones of the oldest South w Trough-cross bedding African hominid.Science 269,521-524 (1995) 10.Deloison,Y.Anatomie des os fossiles de pieds des hominides d'Afrique du Sud. 0 Soil carbonate sample Biomet Hum.Anthropol.21,189-230(2003) Altered tuff 11.Lovejoy.O.C.,Latimer,B.Suwa,G.Asfaw,B.White,T.D.Combining prehension and propulsion:The foot of Ardipithecus ramidus.Science 326,72(2009) ★ BRT-VP-2/73 12.Ward,C.V Kimbel,W.H.Johanson,D.C.Complete fourth metatarsal and arches in the foot of Australooithecus afarensis.Science 331,750-753(2011). Vertebrate fossil 13.Harcourt-Smith,W.E.H.Aiello,L C.Fossils,feet and the evolution of human horizon bipedal locomotion.J.Anat 204.403-416 (2004). 画N⑨ 14. Latimer,B.M.Lovejoy,C.O.Hallucal tarsometatarsal joint in Australopithecus Burtele tuff:3.469+0.008 Myr ago afarensis.Am.J.Phys.Anthropol.82,125-133(1990). (average of WM07/B-1 and WM10/B-1) 15.Griffin,N.L&Richmond,B.G.Joint orientation and function in great ape and human proximal pedal phalanges.Am.J.Phys.Anthropol.141,116-123(2010) 16.Latimer,B.M.&Lovejoy.C.O.Metatarsophalangeal joints of Australopithecus bbbb afarensis.Am.J.Phys.Anthropol.83,13-23(1990). 17.Walker,A C.Pickford,M.in New Interpretaions of Ape and Human Ancestry (eds Ciochon,R.L.Corruccini.R.S.)325-413(Plenum,1983) 18.White,T.D.Suwa.G.Hominid footprints at Laetoli:facts and interpretations.Am. Figure 5Stratigraphic section at the BRT localities and placement of the Phys.Anthropol.72,485-514(1987). 19.Elftman,H.Manter.J.Chimpanzee and human feet in bipedal walking.Am.J. BRT-VP-2/73 partial foot skeleton.The Burtele tuff is dated by the Ar/Ar Phys.Anthropol 20,69-79(1935). method to 3.469+0.008 Myr ago and lies a maximum of about 27 m below 20.Elftman,H.Manter,J.The evolution of the human foot with special reference to BRT-VP-2/73,providing a maximum age constraint of ~3.47 Myr ago for the the joints.J.Anat.70,56-67 (1935). foot specimen (shown by the black star)and for three fossiliferous sandstone 21 DeSilva,J.M.Functional morphology of the ankle and the likelihood of climbing in horizons (shown by vertical lines)at BRT-VP-1 and BRT-VP-2.An 22. approximate age for the foot specimen,using regional sediment accumulation DeeVaSegment and joint angles of hind limb during bipedal and quadrupedal walking of the bonobo rates,suggests an age of between 3.2 and 3.4 Myr ago for BRT-VP-2/73(see (Pan paniscus).Am.J.Phys.Anthropol.119,37-51(2002). Methods for details).S,F,M,C,P indicates soil,flaggy,mudstone,coarse and 23.Vereecke,E D'Aout,K..De Clercg.D..Van Elsacker,L&Aerts,P.Dynamic plantar pebbly sandstone,respectively;it shows the degree of resistance to erosion and pressure distribution during terrestrial locomotion of bonobos(Pan paniscus).Am. rock stiffness. J.Phys.Anthropol.120,373-383(2003). 24.Walter,R.C.Aronson,J.L.Age and source of the Sidi Hakoma Tuff,Hadar METHODS SUMMARY Formation,Ethiopia.J.Hum.Evol.25,229-240(1993). 25.deMenocal,P.B.Brown,F.H.in Hominid Evolution and Climatic Change in Europe The Burtele tuff at the base of the section is dated by the 4Ar/Ar method to (eds Agusti,J.Rook,L Andrews,P.)23-54(Cambridge Univ.Press,1999). 3.4690.008 Myr ago (analytical data are given in Supplementary Information) 26.McDougall,I.Brown,F.H.Geochronology of the pre-KBS Tuff sequence,Omo and lies a maximum ofabout 27 m below BRT-VP-2/73,providing a firm maximum Group,Turkana Basin.J.Geol.Soc Lond165,549-562(2008) age constraint of~3.47 Myr ago for the foot specimen(Fig.5).An approximate age 27.Passey,B.H.,Levin,N.E.Cerling.T.E Brown,F.H.Eiler,J.M.High-temperature environments of human evolution in East Africa based on bond ordering in for the foot specimen can be estimated using regional sediment accumulation rates paleosol carbonates.Proc.Natl Acad.Sci.USA 107,11245-11249 (2010). The average rate for older WORMIL strata in the Waki-Mille confluence area is 11 cm kyr(ref.2),which yields an estimated age of 3.22 Myr ago for the BRT-VP- Supplementary Information is linked to the online version of the paper at 2/73 specimen.This rate is much lower than estimates for the Sidi Hakoma Member www.nature.com/nature. of the Hadar Formation,which is closer in age to the BRT ridge section,but is Acknowledgements We thank the Authority for Research and Conservation of Cultural much farther away geographically.Using a Sidi Hakoma accumulation rate of Heritage and the Afar Regional State of Ethiopia for permission to conduct field and 30 cm kyr yields an estimate of3.38 Myr ago for BRT-VP-2/73.These contrasting laboratory research,and the Afar people of the Woranso-Mille area for support in the rates indicate an age of between 3.2 and 3.4 Myr ago for BRT-VP-2/73. field.We also thank M.Asnake,R.Bernor.S.Frost,D.Geraads,I.Giaourtsakis,M.Lewis. W.Sanders and L Werdelin for faunal identifications We thank B.Passey for aid with For the isotopic analysis of pedogenic carbonate,carbonate nodules were isotope analyses;E.Guthrie for unpublished primary data;L Russell for photography; sampled from peds with slickenside surfaces and clay cutans,within a distinct S.Melillo and H.Gebreyesus for fieldwork:O.Lovejoy,S.Simpson,G.Suwa andT.White pedogenic carbonate zone,250 cm below the palaeosol contact with the over- for comments and discussions;D.Su for discussions and assistance in statistical lying silt.C,O and A measurements of carbonate were made using an analysis;and L Jellema for assistance in photography.This research was supported by automated common acid bath peripheral coupled to a Thermo MAT 253 mass funding from the LSB Leakey Foundation,the National Geographic Society.the Cleveland Museum of Natural History,and NSF grants BCS-0234320,BCS-0321893 spectrometer at Johns Hopkins University,using methods described previously27 BCS-0542037 and BCS-1124705. The results are reported in Supplementary Table 8. Author Contributions Y.H.-S.and B.M.L conducted the description and comparative Full Methods and any associated references are available in the online version of analysis.B.Z.S.,N.E.L and M.A compiled the stratigraphic sequence.A.D.conducted the paper at www.nature.com/nature. the radiometric dating.N.E.L conducted stable isotope analysis.Y.H.-S.and B.M.L wrote the paper with input from all authors. Received 22 October 2011;accepted 8 February 2012. Author Information Reprints and permissions information is available at www.nature.com/reprints.The authors declare no competing financial interests. 1.Haile-Selassie,Y.Deino,A,Saylor,B..Umer,M.Latimer,B.Preliminary geology Readers are welcome to comment on the online version of this arcle at and paleontology of new hominid-bear g Pliocene localities in the central Afar www.nature.com/nature.Correspondence and requests for materials should be region of Ethiopia.Anthropol Sci.115,215-222 (2007). addressed to Y.H.-S.(yhailese@cmnh.org). 29 MARCH 2012 VOL 483 NATURE 569 2012 Macmillan Publishers Limited.All rights reservedMETHODS SUMMARY The Burtele tuff at the base of the section is dated by the 40Ar/39Ar method to 3.4696 0.008 Myr ago (analytical data are given in Supplementary Information) and lies a maximum of about 27 m below BRT-VP-2/73, providing afirmmaximum age constraint of ,3.47Myr ago for the foot specimen (Fig. 5). An approximate age for the foot specimen can be estimated using regional sediment accumulation rates. The average rate for older WORMIL strata in the Waki-Mille confluence area is 11 cm kyr21 (ref. 2), which yields an estimated age of 3.22 Myr ago for the BRT-VP- 2/73 specimen. This rate is much lower than estimatesfor the Sidi Hakoma Member of the Hadar Formation24–26, which is closer in age to the BRT ridge section, but is much farther away geographically. Using a Sidi Hakoma accumulation rate of 30 cm kyr21 yields an estimate of 3.38Myr ago for BRT-VP-2/73. These contrasting rates indicate an age of between 3.2 and 3.4 Myr ago for BRT-VP-2/73. For the isotopic analysis of pedogenic carbonate, carbonate nodules were sampled from peds with slickenside surfaces and clay cutans, within a distinct pedogenic carbonate zone, $50 cm below the palaeosol contact with the over￾lying silt. d13C, d18O and D47 measurements of carbonate were made using an automated common acid bath peripheral coupled to a Thermo MAT 253 mass spectrometer at Johns Hopkins University, using methods described previously27. The results are reported in Supplementary Table 8. Full Methods and any associated references are available in the online version of the paper at www.nature.com/nature. Received 22 October 2011; accepted 8 February 2012. 1. Haile-Selassie, Y., Deino, A., Saylor, B., Umer, M. & Latimer, B. Preliminary geology and paleontology of new hominid-bearing Pliocene localities in the central Afar region of Ethiopia. Anthropol. Sci. 115, 215–222 (2007). 2. Deino, A. L. et al. 40Ar/39Ar dating, paleomagnetism, and tephrochemistry of Pliocene strata of the hominid-bearing Woranso-Mille area, west-central Afar Rift, Ethiopia. J. Hum. Evol. 58, 111–126 (2010). 3. Haile-Selassie, Y., Saylor,B. Z., Deino, A., Alene,M. & Latimer, B. New hominid fossils fromWoranso-Mille (Central Afar, Ethiopia) the taxonomy of earlyAustralopithecus. Am. J. Phys. Anthropol. 141, 406–417 (2009). 4. Haile-Selassie, Y. et al. An early Australopithecus afarensis postcranium from Woranso-Mille, Ethiopia. Proc. Natl Acad. Sci. USA 107, 12121–12126 (2010). 5. Haile-Selassie, Y. Phylogeny of early Australopithecus: new fossil evidence from the Woranso-Mille (Central Afar, Ethiopia). Phil. Trans. R. Soc. B 365, 3323–3331 (2010). 6. Latimer, B. M. & Lovejoy, C. O. Hominid tarsal, metatarsal, and phalangeal bones recovered from the Hadar formation: 1974–1977 collections. Am. J. Phys. Anthropol. 57, 701–719 (1982). 7. Day, M. H. & Napier, J. R. Hominid fossils from Bed I, Olduvai Gorge, Tanganyika: fossil footbones. Nature 201, 969–970 (1964). 8. Zipfel, B. et al. The foot and ankle of Australopithecus sediba. Science 333, 1417–1420 (2011). 9. Clarke, R. J. & Tobias, P. V. Sterkfontein Member 2 foot bones of the oldest South African hominid. Science 269, 521–524 (1995). 10. Deloison, Y. Anatomie des os fossiles de pieds des hominides d’Afrique du Sud. Biomet. Hum. Anthropol. 21, 189–230 (2003). 11. Lovejoy, O. C., Latimer, B., Suwa, G., Asfaw, B. & White, T. D. Combining prehension and propulsion: The foot of Ardipithecus ramidus. Science 326, 72 (2009). 12. Ward, C. V., Kimbel, W. H. & Johanson, D. C. Complete fourthmetatarsal and arches in the foot of Australopithecus afarensis. Science 331, 750–753 (2011). 13. Harcourt-Smith, W. E. H. & Aiello, L. C. Fossils, feet and the evolution of human bipedal locomotion. J. Anat. 204, 403–416 (2004). 14. Latimer, B. M. & Lovejoy, C. O. Hallucal tarsometatarsal joint in Australopithecus afarensis. Am. J. Phys. Anthropol. 82, 125–133 (1990). 15. Griffin, N. L. & Richmond, B. G. Joint orientation and function in great ape and human proximal pedal phalanges. Am. J. Phys. Anthropol. 141, 116–123 (2010). 16. Latimer, B. M. & Lovejoy, C. O. Metatarsophalangeal joints of Australopithecus afarensis. Am. J. Phys. Anthropol. 83, 13–23 (1990). 17. Walker, A. C. & Pickford, M. in New Interpretaions of Ape and Human Ancestry (eds Ciochon, R. L. & Corruccini, R. S.) 325–413 (Plenum, 1983). 18. White, T. D. & Suwa, G. Hominid footprints at Laetoli: facts and interpretations. Am. J. Phys. Anthropol. 72, 485–514 (1987). 19. Elftman, H. & Manter, J. Chimpanzee and human feet in bipedal walking. Am. J. Phys. Anthropol. 20, 69–79 (1935). 20. Elftman, H. & Manter, J. The evolution of the human foot with special reference to the joints. J. Anat. 70, 56–67 (1935). 21. DeSilva, J. M. Functional morphology of the ankle and the likelihood of climbing in early hominins. Proc. Natl Acad. Sci. USA 106, 6567–6572 (2009). 22. D’Aout, K., Aerts, P., De Clercq, D., De Meester, K. & Van Elsacker, L. Segment and joint angles of hind limb during bipedal and quadrupedal walking of the bonobo (Pan paniscus). Am. J. Phys. Anthropol. 119, 37–51 (2002). 23. Vereecke, E., D’Aout, K., De Clercq, D., Van Elsacker, L. & Aerts, P. Dynamic plantar pressure distribution during terrestrial locomotion of bonobos (Pan paniscus). Am. J. Phys. Anthropol. 120, 373–383 (2003). 24. Walter, R. C. & Aronson, J. L. Age and source of the Sidi Hakoma Tuff, Hadar Formation, Ethiopia. J. Hum. Evol. 25, 229–240 (1993). 25. deMenocal, P. B. & Brown, F. H. in Hominid Evolution and Climatic Change in Europe (eds Agusti, J., Rook, L. & Andrews, P.) 23–54 (Cambridge Univ. Press, 1999). 26. McDougall, I. & Brown, F. H. Geochronology of the pre-KBS Tuff sequence, Omo Group, Turkana Basin. J. Geol. Soc. Lond. 165, 549–562 (2008). 27. Passey, B. H., Levin, N. E., Cerling, T. E., Brown, F. H. & Eiler, J. M. High-temperature environments of human evolution in East Africa based on bond ordering in paleosol carbonates. Proc. Natl Acad. Sci. USA 107, 11245–11249 (2010). Supplementary Information is linked to the online version of the paper at www.nature.com/nature. Acknowledgements We thank the Authority for Research and Conservation of Cultural Heritage and the Afar Regional State of Ethiopia for permission to conduct field and laboratory research, and the Afar people of the Woranso-Mille area for support in the field. We also thank M. Asnake, R. Bernor, S. Frost, D. Geraads, I. Giaourtsakis, M. Lewis, W. Sanders and L. Werdelin for faunal identifications. We thank B. Passey for aid with isotope analyses; E. Guthrie for unpublished primary data; L. Russell for photography; S. Melillo and H. Gebreyesus for fieldwork; O. Lovejoy, S. Simpson, G. Suwa and T. White for comments and discussions; D. Su for discussions and assistance in statistical analysis; and L. Jellema for assistance in photography. This research was supported by funding from the LSB Leakey Foundation, the National Geographic Society, the Cleveland Museum of Natural History, and NSF grants BCS-0234320, BCS-0321893, BCS-0542037 and BCS-1124705. Author Contributions Y.H.-S. and B.M.L. conducted the description and comparative analysis. B.Z.S., N.E.L. and M.A. compiled the stratigraphic sequence. A.D. conducted the radiometric dating. N.E.L. conducted stable isotope analysis. Y.H.-S. and B.M.L. wrote the paper with input from all authors. Author Information Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests. Readers are welcome to comment on the online version of this article at www.nature.com/nature. Correspondence and requests for materials should be addressed to Y.H.-S. (yhailese@cmnh.org). Soil Pebbly sandstone Coarse sandstone Flaggy sandstone Mudstone and sandstone Basalt Gastropod layer Planar laminations Parting lineations Ripple stratification Trough-cross bedding Soil carbonate sample Altered tuff Vertebrate fossil horizon BRT-VP-2/73 Burtele tuff: 3.469 ± 0.008 Myr ago (average of WM07/B-1 and WM10/B-1) S F MCP Mesa 0 m 10 20 30 Sandstone ridges of BRT-VP-1,2 Burtele (BRT) WM11-BRT-141 WM11-BRT-140 P.L. P.L. Figure 5 | Stratigraphic section at the BRT localities and placement of the BRT-VP-2/73 partial foot skeleton. The Burtele tuff is dated by the 40Ar/39Ar method to 3.469 6 0.008 Myr ago and lies a maximum of about 27 m below BRT-VP-2/73, providing a maximum age constraint of ,3.47 Myr ago for the foot specimen (shown by the black star) and for three fossiliferous sandstone horizons (shown by vertical lines) at BRT-VP-1 and BRT-VP-2. An approximate age for the foot specimen, using regional sediment accumulation rates, suggests an age of between 3.2 and 3.4Myr ago for BRT-VP-2/73 (see Methods for details). S, F, M, C, P indicates soil, flaggy, mudstone, coarse and pebbly sandstone, respectively; it shows the degree of resistance to erosion and rock stiffness. ARTICLE RESEARCH 29 MARCH 2012 | VOL 483 | NATURE | 569 ©2012 Macmillan Publishers Limited. All rights reserved