Age of Lucy and the First Family: Single-crystal 40Ar/39Ar dating of the Denen Dora and lower Kada Hadar members of the Hadar Formation, Ethiopia

Research Article| January 01, 1994 Age of Lucy and the First Family: Single-crystal 40Ar/39Ar dating of the Denen Dora and lower Kada Hadar members of the Hadar Formation, Ethiopia Robert C. Walter Robert C. Walter 1Geochronology Center, Institute of Human Origins, 2453 Ridge Road, Berkeley, California 94709 Search for other works by this author on: GSW Google Scholar Geology (1994) 22 (1): 6–10. https://doi.org/10.1130/0091-7613(1994)022<0006:AOLATF>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Robert C. Walter; Age of Lucy and the First Family: Single-crystal 40Ar/39Ar dating of the Denen Dora and lower Kada Hadar members of the Hadar Formation, Ethiopia. Geology 1994;; 22 (1): 6–10. doi: https://doi.org/10.1130/0091-7613(1994)022<0006:AOLATF>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Single-crystal laser-fusion 40Ar/39Ar analyses on previously undatable tephra deposits provide the first reliable dates for the important hominid fossils popularly called "Lucy" and the "First Family,"here dated to 3.18 and 3.20 Ma, respectively. These results help to establish an age framework for hominid and biostratigraphic evolution for the fossil-rich Hadar Formation. The abundance of well-preserved vertebrate fossils at Hadar can be attributed, in part, to an unusually high sediment-accumulation rate of approximately 80 cm/ka, which might be due to increased tectonic subsidence of the Hadar basin between 3.4 and 3.2 Ma. The new dates also provide supportive evidence that the boundary ages for the Kaena and Mammoth subchrons, of the geomagnetic polarity time scale, need to be increased by as much as 4% to 5%. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.