On the Environment of Aramis: Concerning Reply of White to Cerling et al. in August 2014

Abstract

White (2014) made several comments on our paper (Gani and Gani 2011) while replying to Cerling et al. (2014). His comments contradict our field descriptions presented in Gani and Gani (2011). Based on our fieldwork at the Aramis site, Ethiopia, where a near-complete skeleton of Ardipithecus ramidus was excavated, we presented our field data with their analysis and interpretation in Gani and Gani (2011). We interpreted our data to indicate the presence of rivers and associated mixed vegetation (grasses and trees) in adjacent floodplains, which constitute the environmental context of the very place and time where/whenA. ramidus likely lived and died. It is a well-known fact that scientists can have different interpretations while scrutinizing the same data set, but their field descriptions (that constitute the data set) should not be contradicting. Therefore, in this reply, we focus on the basic field observations and descriptions (rather than the interpretations) of Gani and Gani (2011) that White questioned. White (2014) states that Gani and Gani (2011) “mistook a nearby tufa with uncemented mudstone pellets deposited in standing shallow water as a crossbedded fluvial sandstone” (471). Tufa is a nonclastic limestone formed by the in situ precipitation of carbonate minerals in fluvial or lake environments, whereas sandstone is a clastic sedimentary rock composed of sand-sized (0.063–2 mm) detrital (i.e., transported) grains like quartz, feldspar, and lithoclast. Therefore, it should not be difficult to differentiate tufa from sandstone in the field. Although we cannot discredit the presence of tufa in nearby localities, we observed the sedimentary rock in question with a hand lens (20#) and a grain-size card and determined it to be a fine-grained (0.125–0.25 mm) sandstone composed of various detrital grains including quartz. In these sandstone beds, we found numerous scattered lithoclasts of igneous origin that