They are generally thought to be members of the species Australopithecus afarensis.
There are multiple theories about the hominids’ cause of death and some debate over their species and sexual dimorphism.
In the process of reworking, these ashes can pick up pre-existing detrital grains that, by definition, are older than the juvenile ash.
If during K-Ar analyses these detrital grains are not recognized and eliminated then they can cause the measured ages to be systematically too old.
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But absolute dating had to be used to ascertain that time.
The recovery of these 216 hominid specimens is unique in African paleoanthropology, since the close proximity of the different fossils suggests that these were individuals who might have lived in a group or been part of the same family.
Of the 216 specimens, 197 were surface finds, and 19 were found within 80 cm in the ground, suggesting a common time of death.
In 1972, Taieb invited Yves Coppens, a French paleontologist, Jon Kalb, an American geologist, and Donald Johanson, an American anthropologist, to survey the region in order to appraise the area’s field exploration potential.
They soon settled on working in the Hadar Formation, a sedimentary geological formation within the region.
Such numerical calibrations are crucial to understanding rates and timing of evolutionary change.