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In addition, there was discussion among the reviewers during the consultation process concerning the last line of the Abstract and the penultimate paragraph of the Discussion (that begins on line 1009), which were viewed as unnecessarily critical of prior authors' work and of the challenges in accurately dating hominin fossils. It is difficult to estimate whether Rn degassing occurred during the entire burial history of the teeth. This is a statistical averaging technique for aliquots that display a high degree of within-sample scatter (Olley et al., 2004; Galbraith et al., 2005), but still combines some grains that are well-bleached with others that are only partly bleached. (b, c) Locations of LA-ICP-MS spot analyses for teeth samples 1788 (b) and 1810 (c) conducted by GU-ANU. The error on the luminescence age estimates represents the combined systematic and experimental error associated with both the De and dose rate values. We have also updated our summary diagram (Figure 14) to make the various relationships clearer. Following deposition of sub-unit 3b and the hominin remains, Flowstones 1b-e were deposited over sub-unit 3b in the entry zone. What evidence is there to suggest that this is the best approach? took these extra steps to make sure that the results obtained were reproducible and unbiased. To provide more, would transform the paper into a review paper, which is not the intent here. […] Dating that places these specimens at 200-300 ka suggests several scenarios. This seems rather arbitrary when in fact it is something that could be either modeled or calculated statistically. Multiple samples were taken from each layer within the flowstone speleothem and analysed using Fisher statistics and the Program FISH2 to establish the Palaeolatitude (Plat.) is not confirmed by evidence and, again, is just a hypothesis. In response to the main editorial issues: We believe that this has now been addressed; see our detailed comments in response to reviewers 3 and 4 in particular. Both laboratories employed a Single Saturating Exponential (SSE) fitting function. We have explained this approach in detail in the revised manuscript. Outside of the chamber then being transported in via the debris cone? Dates acquired via U-Th and ESR techniques were obtained using a double blind approach for each technique to ensure robust, reproducible results, with each laboratory using their own analytical and computational approach. It would be more appropriate to say that Unit 3 is a reworked unit and that different deposits of it in the chamber may have been deposited at different times. H. naledi unquestionably has primitive characteristics and originally was expected to date to at least 1 Ma. Following this initial work, no further radiocarbon studies were carried out. Filming. All 3 of their samples from 2 different parts of the cave say Unit 1 is younger than Unit 2. The variation in the gamma dose rate shows no clear trend with depth (Figure 10), and the samples along the vertical profile were used to obtain an average gamma dose rate. Normalised dose response curves (DRC’s) are shown in Figure 11. Measurements were performed at an ablation rate of 20 Hz and a translation speed of 50 μm/s. The specimen was recovered from a sediment sample taken at a depth of 55–60 cm below the original ground surface of the cave floor near the base of the sondage dug in the centre of the excavation pit (Figures 1b, 2d and 4). (a) U.W.101–1767; (b) U.W.101–1788; (c) U.W.101–1810. However, the paper simply contains too much information, and we are not able to provide all of it in the abstract. All units and sub-units are time-transgressive, meaning that they are lithostratigraphic units and not chronostratigraphic units that occur in strict temporal order. Also a small amount of dentine if it had existed would make little difference regarding the result. The reviewers asked for a methodology section up front. In the paper we have treated the three facies as if they are all part of the same stratigraphic unit (they have the same composition and share a high content of characteristic, orange cave mud; Dirks et al., 2015). All the sampled flowstones formed as sheets, crusts, or drapes overlying older sediment units, with the exception of samples RS13 and RS18, which were taken from a small stalactite that formed along the lip of an erosional remnant of Flowstone 1c. The three age estimates are consistent with the stratigraphic position of the three phases in Flowstone 1a, and they indicate that the erosion remnant of Unit 2 encrusted by Flowstone 1a is also older than 780 ka. Accepted, a mistake was made in the figure in Dirks et al. The upper surface has a rough pitted appearance as a result of partial resorption/dissolution along grain boundaries of the acicular crystals. We appreciate that this is difficult to accept, but we can find no evidence to refute this claim. This showed that the differences in US-ESR and CSUS-ESR model ages are less than 4%, thats is, which is well within the uncertainty ranges of the listed US-ESR ages (Table 7). It was, therefore, decided not to pursue more detailed OSL studies at this stage, even though we did carry out preliminary tests for single grain and feldspar analyses at the University of Wollongong, to assess the suitability of these techniques. However, the suggestion that there has been little actual input from these authors is certainly not true. There are many examples in sed/strat where the same/similar facies are repeated multiple/different times in a succession. 4) In the description of Unit 3, angular to sub-angular grains are classified as being reworked – on what basis? Dentine measurements are consistent along the measured sections with small regions affected by leaching and enrichment near cracks and the pulp cavity. The Minimum Age Model (MAM) is used if incomplete bleaching is expected to be the reason for an observed skewed dose distribution, or if (as in this case) the sample contains mineral grains that have never been at surface (Galbraith et al., 1999). Eux aussi veulent profiter des royaumes en construction… Malheureusement, ce sera à vos dépens…Age of Giants est une extension pour les jeux Kingdomino et Queendomino. Laminations along the basal 3–4 mm of this flowstone are brown in colour, whereas the top 10–12 mm of this flowstone layer consists of what is possibly a separate, younger unit of laminated grey-brown carbonate with small pore spaces developed along some of the laminar surfaces. Sample 1810: This lower left molar or premolar from the excavation pit (Figures 4 and 6c), is near complete and only moderately weathered. Dating protocols: U series analysis – Laser ablation U-series analyses were carried out at the Australian National University (ANU), using a custom-built laser sampling system interfaced between an ArF Excimer laser and a Finnigan Neptune MC-ICP-MS (Eggins et al., 2003, 2005), following principles and procedures described in Grün et al. This is one of their main conclusions, yet not specifically supported. His column appeared again in 1995–1996, retitled Envoyé spécial chez moi. This age provides the best minimum age estimate for sub-unit 3b, and by extension a minimum age for the H. naledi fossils. His mother is the daughter of a coal miner from the Nord-Pas-de-Calais region. Subsequent U-Th and ESR work made it clear that carbon dating should not be further pursued, and attempting blind dates at research labs would be pointless as far as the purpose of this study is concerned, and we did not want to unnecessarily impose on people’s time and expenses. Ages are reported relative to 1950. A two-part list of links to download the article, or parts of the article, in various formats. These results suggest that a single uptake event is dated. Account e liste Account Resi e ordini. The sample has been affected by recrystallization resulting in the formation of radiating acicular crystals of calcite that grow from the core outward. It was sampled from a ~14 cm wide vertical flowstone-filled fracture exposed on the surface above the southern end of the Dinaledi Chamber itself. If RS23 is not from the base, or is from higher up and in the Normal section of FS1a, then that needs to be properly documented here. It was found that the older flowstones in the Dinaledi Chamber contained excessive common Pb caused by the inclusion of detrital material (mainly clays) making them unsuitable for U-Pb dating (Dirks et al., 2015). (2015) has caused confusion because it shows a bone with the caption assigning all bones to Hominin, including a bone drawn under flowstone 1a. This has been done to make the techniques more accessible for a wider audience. DE values were obtained by fitting a Single Saturating Exponential (SSE) at the appropriate maximum irradiation dose (Dmax) following Duval and Grün (2016) (using 1767 Dmax = 1264 Gy, 1788 Dmax = 2465 Gy, 1810 Dmax = 2735 Gy and 1841 Dmax = 3526 Gy). The preliminary results have guided the subsequent dating strategy and sampling approach reported here. Because Th is nearly insoluble in surface waters, flowstone does not usually contain initial 230Th, in contrast to U, which is soluble in oxidizing waters and is incorporated into flowstone at low concentrations (generally <5 ppm; e.g., Pickering et al., 2010). Samples were then ground to a powder and pre-treated with 1N acetic acid for 24 hr, rinsed, dried and weighed. Species of ancient humans and the extinct relatives of our ancestors are typically described from a limited number of fossils. The presence of well-articulated remains in the excavation pit away from the chamber entrance indicates that some of the remains entered the cave intact. These grains may be measured collectively in a single composite sample (an aliquot), which provides an average signal, or as individual grains, which provides greater insights into the depositional history of the sediments. We have also added a new Figure 2 to show these relationships more clearly. To ensure reliable DE values, the maximum irradiation dose (Dmax) was selected in accordance with the recommendations made by Duval and Grün (2016), in order to avoid DE overestimation (i.e., for DE values between 100–500 Gy, the Dmax/DE ratio has to be kept between 5–10; for De values between 1000–2000 Gy the Dmax/DE ratio has to be kept between 1–2; Table 10). This is not conventional with U-Th. Your article has been reviewed by five peer reviewers, and the evaluation has been overseen by a Reviewing Editor and Ian Baldwin as the Senior Editor. All Unit 1 ages are younger than Unit 2. As explained, we did do preliminary test work to determine whether to apply U-Pb vs. U-Th dating.

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