TY - JOUR
T1 - Connecting local environmental sequences to global climate patterns
T2 - evidence from the hominin-bearing Hadar Formation, Ethiopia
AU - Campisano, Christopher J.
AU - Feibel, Craig S.
N1 - Funding Information:
This project was funded by grants from the National Science Foundation, the National Geographic Society, the Institute of Human Origins (ASU), and the Center for Human Evolutionary Studies (Rutgers University) to both the authors and directors of the Hadar Research Project. We would like to thank Bill Kimbel, Don Johanson, Erella Hovers, Gerry Eck, Kaye Reed, the Institute of Human Origins, the National Museum of Ethiopia, the Ethiopian A.R.C.C.H., and especially our field crew and friends from the Eloaha region. We would also like to thank Chris Lepre, Erella Hovers, Kay Behrensmeyer, Rick Potts, and particularly Bill Kimbel for comments on an earlier draft; John Kappelman and an anonymous reviewer for their very helpful reviews; and Beth Christensen and Mark Maslin for inviting us to participate in this volume and the related AGU session.
PY - 2007/11
Y1 - 2007/11
N2 - Central to the debate surrounding global climate change and Plio-Pleistocene hominin evolution is the degree to which orbital-scale climate patterns influence low-latitude continental ecosystems and how these influences can be distinguished from regional volcano-tectonic events and local environmental effects. The Pliocene Hadar Formation of Ethiopia preserves a record of hominin paleoenvironments from roughly 3.5 to 2.2 Ma at a temporal resolution relevant to evolutionary change within hominins and other taxa. This study integrates the high-resolution sedimentological and paleontological records at Hadar with climate proxies such as marine core isotope, dust, and sapropel records. Consistent cycling observed both between and within fluvial and lacustrine depositional environments prior to 2.9 Ma at Hadar appears to be predominantly climatic in nature. In contrast a significant change in depositional facies after 2.9 Ma to sequences dominated by conglomerate cut-and-fill cycles indicates a strong tectonic signature related to regional developments in the Main Ethiopian Rift. While specific events seen in marine proxy records may have parallels in the Hadar environmental archive, their overall patterns of high versus low variability may be even more relevant. For example, periods of relatively high-amplitude climate oscillations between 3.15 and 2.95 Ma may be linked to noted size-related morphological changes within the Hadar Australopithecus afarensis lineage and a significant increase in more arid-adapted bovid taxa. Increased aridity in East Africa during this period is also indicated by peaks in eolian dust in the marine core record. Conversely, the dominant lacustrine phase at Hadar ca. 3.3 Ma coincides with the least variable period in several climate proxy records, including marine core foraminifera δ18O values and eolian dust concentration. This phase is also coeval with low insolation variability and a very distinct and significant long-term period of low dust percentage in circum-Africa marine cores.
AB - Central to the debate surrounding global climate change and Plio-Pleistocene hominin evolution is the degree to which orbital-scale climate patterns influence low-latitude continental ecosystems and how these influences can be distinguished from regional volcano-tectonic events and local environmental effects. The Pliocene Hadar Formation of Ethiopia preserves a record of hominin paleoenvironments from roughly 3.5 to 2.2 Ma at a temporal resolution relevant to evolutionary change within hominins and other taxa. This study integrates the high-resolution sedimentological and paleontological records at Hadar with climate proxies such as marine core isotope, dust, and sapropel records. Consistent cycling observed both between and within fluvial and lacustrine depositional environments prior to 2.9 Ma at Hadar appears to be predominantly climatic in nature. In contrast a significant change in depositional facies after 2.9 Ma to sequences dominated by conglomerate cut-and-fill cycles indicates a strong tectonic signature related to regional developments in the Main Ethiopian Rift. While specific events seen in marine proxy records may have parallels in the Hadar environmental archive, their overall patterns of high versus low variability may be even more relevant. For example, periods of relatively high-amplitude climate oscillations between 3.15 and 2.95 Ma may be linked to noted size-related morphological changes within the Hadar Australopithecus afarensis lineage and a significant increase in more arid-adapted bovid taxa. Increased aridity in East Africa during this period is also indicated by peaks in eolian dust in the marine core record. Conversely, the dominant lacustrine phase at Hadar ca. 3.3 Ma coincides with the least variable period in several climate proxy records, including marine core foraminifera δ18O values and eolian dust concentration. This phase is also coeval with low insolation variability and a very distinct and significant long-term period of low dust percentage in circum-Africa marine cores.
KW - Australopithecus afarensis
KW - Depositional environments
KW - Hominin evolution
KW - Pliocene
UR - http://www.scopus.com/inward/record.url?scp=35648972544&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=35648972544&partnerID=8YFLogxK
U2 - 10.1016/j.jhevol.2007.05.015
DO - 10.1016/j.jhevol.2007.05.015
M3 - Article
C2 - 17923150
AN - SCOPUS:35648972544
SN - 0047-2484
VL - 53
SP - 515
EP - 527
JO - Journal of human evolution
JF - Journal of human evolution
IS - 5
ER -