Interpretations of the magnetostratigraphy of the Hadar hominid site, Ethiopia

Schmitt, T. J.; Nairn, A.E.M.

doi:10.1038/309704a0

Cited by 15 publications

(7 citation statements)

References 7 publications

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“…Apparently a volcanic source in the central Ethiopian highlands accounted for the tuff being dispersed over a relatively wide area of eastern Africa. Paleomagnetic results (Schmitt and Nairn, 1984) also support the later date for the Hadar Formation.…”

Section: Asupporting

confidence: 58%

Status ofAustralopithecus afarensis

Boaz

1988

Am. J. Phys. Anthropol.

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Australopithecus afarensis Johanson in Hinrichsen (New Sci. 78(1105):571,1978) is now accepted by many workers as an East African early hominid species showing marked sexual dimorphism dating to between 2.8 and 3.8 million years before present (my BPI and possibly as early as 5.0 my BP. It is best known in the latter part of this time range, at Hadar, and is here most phenetically similar to the South African A. africanus. In the earlier part of its time range, at Laetoli and Middle Awash, the morphology of the species is less well known. Much debate has surrounded the taxonomy, dating, morphological adaptations, and phylogenetic interpretation of the Laetoli and Hadar hominids. Some questions, such as the geological age of the sites, are close to resolution. Other questions hinge on whether the Laetoli and Hadar fossil samples are drawn from one biological population or species or from more than one. At present the balance of evidence suggests attribution of the Laetoli and Hadar fossils to a single species. Different emphases in functional morphological studies have led to differences in interpretations of taxonomy, phylogeny, function, and behavior. Various lines of evidence document that A. afarensis engaged in humanlike bipedal locomotion, but its postcranial morphology also documents that the species' locomotor adaptation differed from that of Homo, perhaps toward a more climbing and arboreal adaptation. Cladistic relations between A. afarensis and A. robustuslboisei are unresolved. A. afarensis does appear to be a n appropriate ancestor for the A. africanus-Homo lineage.The specimens identified as belonging to A ustralopithecus afarensis derive from different areas of eastern Africa. Some were discovered decades apart, by different investigators, and have been attributed to different taxa. To evaluate the current status of the taxon A. afarensis requires the consideration of several lines of evidence, among which are the morphology of the specimens, the geological ages of the sites that yielded them, the taxonomic and systematic assignations of the specimens, and the phylogenetic interpretations that derive from them. This paper considers all of these issues but begins with a brief review of the history of the discoveries of the fossils.

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Section: Asupporting

confidence: 58%

Status ofAustralopithecus afarensis

Boaz

1988

Am. J. Phys. Anthropol.

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“…As a result, sediments of the Hadar Basin have been studied intensively since the 1970s. Successful dating has been achieved using the combination of radiochronologic methods (mainly 40 Ar/ 39 Ar) on interlayered volcanic deposits and magnetostratigraphy (Aronson et al, 1977;Schmitt and Nairn, 1984;Renne et al, 1993;Tamrat et al, 1996;Walter and Aronson, 1993;Walter, 1994). Understandably, most geological work (e.g., Campisano and Feibel, this volume, and references therein) has focused on regions with high densities of fossil fi nds in the Hadar research area (Fig.…”

Section: Introductionmentioning

confidence: 99%

Magnetostratigraphy of the eastern Hadar Basin (Ledi-Geraru research area, Ethiopia) and implications for hominin paleoenvironments

Dupont‐Nivet

Sier

Campisano³

et al. 2008

The Geology of Early Humans in the Horn of Africa

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“…The age of the samples is well constrained by Ar 40 ͞Ar 39 dating of the main marker tuffs (12,13), paleomagnetic measurements (14,15), and stratigraphic correlation between sections at Hadar and Hurda, a few kilometers east of the Kada Hadar (ref. 16 and Fig.…”

mentioning

confidence: 99%

High-resolution vegetation and climate change associated with Pliocene Australopithecus afarensis

Bonnefille

Potts

Chalié

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

202

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Plio-Pleistocene global climate change is believed to have had an important influence on local habitats and early human evolution in Africa. Responses of hominin lineages to climate change have been difficult to test, however, because this procedure requires well documented evidence for connections between global climate and hominin environment. Through high-resolution pollen data from Hadar, Ethiopia, we show that the hominin Australopithecus afarensis accommodated to substantial environmental variability between 3.4 and 2.9 million years ago. A large biome shift, up to 5°C cooling, and a 200-to 300-mm͞yr rainfall increase occurred just before 3.3 million years ago, which is consistent with a global marine ␦ 18 O isotopic shift.

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Interpretations of the magnetostratigraphy of the Hadar hominid site, Ethiopia

Cited by 15 publications

References 7 publications

Status ofAustralopithecus afarensis

Status ofAustralopithecus afarensis

Magnetostratigraphy of the eastern Hadar Basin (Ledi-Geraru research area, Ethiopia) and implications for hominin paleoenvironments

High-resolution vegetation and climate change associated with Pliocene Australopithecus afarensis

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