PONE-D-20-12918

Techno-functional and 3D shape analysis applied for investigating the variability of backed tools in the Late Middle Paleolithic of Central Europe.

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Reviewers greatly appreciated your work and they suggest only minor revisions. I would suggest to follow the comment of Rev. 1, who suggest to shorten some parts of the manuscript. Once the revisions will be submitted along with your rebuttal letter, I think i will be able to take a decision rapidly.

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Reviewer #1: Manuscript Number: PONE-D-20-12918

Title: Techno-functional and 3D shape analysis applied for investigating the variability of backed tools in the Late Middle Paleolithic of Central Europe

Authors: Delpiano, Davide

Uthmeier, Thorsten

The study “Techno-functional and 3D shape analysis applied for investigating the variability of backed tools in the Late Middle Paleolithic of Central Europe” by Davide Delpiano and Thorsten Uthmeier analyzes backed tools from the late Middle Paleolithic “G-Layers” of the southern German site “Sesselfelsgrotte”. They use a combined approach of techno-functional analyses and 3D geometric morphometrics. Their main finding is the relatedness of backed unifacial tools (“scrapers”) and bifacial tools (Keilmesser). As scrapers are mostly a characteristic of Mousterian assemblages, and bifacial tools of the central European Micoquian or Keilmessergruppen, the authors provide here a strong argument for the relatedness of these technocomplexes. Further, they interpret the emergence of Keilmesser as an ecological answer to the climatic shifts at the beginning of the last glacial cycle in Central Europe.

The paper represents a profound lithic analysis, combining several methods and lines of evidence to deal with the main research aims. The statistics are correct; the limit of the p-value is explained, and the study does not suffer from “over-testing”. The analysis is based on a large dataset from a rich site with various occupations. That represents a reasonable baseline for the interpretations given in the paper. I suggest the publication of the article after the authors have revised some minor issues.

General comments:

(1) I would strongly suggest capitalizing the noun “Keilmesser” as it is a specific name. Further, I advise the authors to remove the plural “s” from Keilmesser. In German, singular and plural of Keilmesser is the same (das Keilmesser, die Keilmesser) and I think this should be done in the same way in English (as it is a German term in an English text).

(2) When reading the paper, I can understand that every argument has its specific reason and makes sense. However, I think that parts of the paper are too long and can be shortened. As PLOS ONE accepts articles of any length, I leave the decision to the editor and the authors. Therefore, the following points are just suggestions. I could imagine merging the Introduction with chapter 2 and parts of chapter three. Other aspects of chapter 3, like the stratigraphy of Sesselfelsgrotte could be moved to the Materials section. Also, I do not think that it is necessary for the main plot of the paper to explain Richter’s models in detail here. Maybe there are some aspects of the site description that could also be moved to the SI? Furthermore, I think that chapter 7.4 is maybe a little bit too much. I don´t think that the issue of the emergence of the Keilmessergruppen could be solved with the data from the analysis presented here.

(3) Some of the plots and diagrams are done in R. But I could not find any citation or mention of the use of this software in the Methods section. I ask the authors to please add which steps (data management etc.) they did in R and which packages they used.

(4) I am missing a brief discussion within the 3DGM section about which aspects of shape change PC1 and PC2 account for. If I am correct, it is visible in the color coding of the displayed shapes in Fig. 13a. I think the analysis would benefit from adding some ideas here. It would be interesting, for example, to see where the different TFS plot in the PCA of shape space.

Specific Comments

Abstract:

a. “In the Late Middle Paleolithic of central Europe” – I think the authors can capitalize “Central”. They should look through the text as both versions occur.

Introduction:

a. “Königsaue was originally dated to MIS 5c [33]”: this is not correct. Königsaue was originally dated to Oderadde which correlates with MIS 5a. See here also the discussion by Jöris (citation [26]), or Mania 2002.

b. “Both the “long chronology” and the “short chronolgy” agree that a large number of sites from secure stratigraphical contexts and with reliable absolute dates fall into a period between the end of MIS 4 and the first part of MIS 3. Among these sites are Salzgitter-Lebenstedt [19,37], Lichtenberg [18], Sesselfelsgrotte [38,39], Verpillière I and II [40], Ciemna and Oblazowa [41,42], Pietraszyn 49 [43] and Kůlna [44]. (Fig. 1)”: I advise the authors to be cautious here with Lichtenberg and Salzgitter-Lebenstedt. The Lichtenberg artifacts come from a cryoturabted context which yielded TL-dates between late MIS 5 and MIS 3 (see Veil et al. 1994 for descriptions). The MIS 3 date is just a calculated model age, which results in a rather insecure age attribution for the find layer. The same applies for Salzgitter: although Pastoors 2001 (and 2009) provides good and reasonable evidence for a MIS 3 age of the site, the radiocarbon ages are close to the limit of the method and the stratigraphic context is far from simple (e.g., 19 geological horizons with finds). Alternative interpretations with a late MIS 5 age are also reasonable and should be considered (see here also Jöris [26]). Securely dated assemblages that are not mentioned here and that should be included (also in the map) are: Pouch, Saxony-Anhalt (MIS 3, OSL: Weiss 2015 Quartär and Weiss 2018 [60]), and Wroclaw Hallera Avenue, Poland (MIS 5 and MIS 3, OSL: Wisniewski et al. 2013, Occupation dynamics north of the Carpathians and Sudetes during the Weichselian (MIS5d-3): The Lower Silesia (SW Poland) case study).

c. “relationship between Mousterian and /Keilmessergruppen/M.M.O.”: please remove the “/” before Keilmessergruppen

Chapter 2: Relevance of backed tools…

a. “As suggested by the direct translation from the original german noun”: please capitalize “German”

b. “as well as in several polish assemblages being part of the so-called “Bockstein group”: “Polish”

c. “In the most recent Keilmessergruppen/M.M.O. sites, Levallois débitage is however usually dominant, in both its recurrent centripetal and recurrent parallel/unipolar variants, as attested in Sesselfelsgrotte, Königsaue, Salzgitter-Lebenstedt and Lichtenberg and other sites [9,18,19,33,35,50]” : Lichtenberg has only one prepared core. Based on facetted flake platforms, Veil et al. only suggest the presence of Levallois. However, they also note that the facetted platforms can equally result from bifacial reduction. Additionally, the authors state the same in chapter 7.3: “Within some open-air, short-term occupations, keilmessers and related artefacts can represent the whole assemblage, with the absence of core-reduction technologies (i.e. in Lichtenberg [18] or Zwolén [31])”

Chapter 3.1 Lithic assemblage data

a. Some references in this chapter (“Both the archaeology and the environmental studies were published in a monograph series (Weißmüller 1995; Richter 1997; Böhner 2008; Dirian 2004; Freund 1998; Freund and Richter 2017; 2018) or in articles (Richter 2002; Richter et al. 2000; Rathgeber 2006)”) are not formatted correctly

Chapter 3.2 Lithic assemblage data

a. Fig. 3: initial- and konsekutivinventar just with one “a” (not “Inventaar”)

Chapter 5.1 TFU analysis

a. “relevance of the techno-functional needs and the various ecological constraints that thir makers and users were confronted with”: “their”

Chapter 6.1.2 Metrical data

a. “Among the KMs, the overall smaller width mean and standard deviationcomes to the eye”: “deviation comes”

Chapter 6.2.1: Techno-functional schemes

a. “If bifacially worked, artifacts of the TFS 1 recall keilmesser types like Bocksteinmesser or Balver Messer.”: Readers not familiar with Keilmesser might ask what the last two terms are, as they are not explained in the text. I would suggest to either give a citation (e.g., Bosinski 1967), remove it, or explain it briefly.

b. “Techno-functional scheme 2 (TFS 2)”: “2a” is not labelled in the figure (Fig. 8), just “2” and “2b”. Further, already 2a, as illustrated in the figure, resembles a Lichtenberg Keilmesser with its oval outline, the elongated bow and the sharp distal tip. Although having a rounded tip, the specimen displayed in Fig. 8: 2b, is rather untypical for a Lichtenberg Keilmesser. See the definitions given in Veil et al. 1994 (“Idealtyp” and additional forms), as well as the drawings therein.

Chapter 6.3 3D morphological data

a. Table 9 & Table 10: What exactly is the number given in the Variability column? How is this number calculated and what does the number express about variability? E.g., what number relates to a low and what number to a high variability? Or is the interpretation of high and low variability just the numbers relative to each other? I would suggest adding one or two sentences to explain these values.

Chapter 7.1 One, no one and one hundred….

a. “3. One group with a curved or convex cutting edge (schemes 6/7 and 7), comprising 5 tools or 8.6%.”: I just like to add that group 1 also has a convex cutting edge (TFS 1 and 2)… maybe it would be better to say “heavily curved cutting edge”

b. “In this sense, keilmesser of scheme 2 could be modified by resharpening to scheme 2b in cases when the tip reshaped into a rounded outline (after it became blunt).” + further sentences: In my opinion this interpretation is a bit vague and may need further techno-functional investigations or experimental replication (I know this is beyond the scope of the paper). Just an example: Let`s say we start with something like 2a. If one thins the distal volume of the piece during resharpening, using the bow and the distal back as striking platform (like in figure 20 upper right specimen), the removal of volume from these edges -and moving towards the proximal parts of the artifact during the process- may result in a piece with a more elongated and longer point + shorter back (as in the Königsaue type). In other words, this strategy of resharpening can lead to results opposed to what the authors suggest (removal or rounding of the point). Generally, both variants may have existed. Maybe the authors should make it clearer that this paragraph is more hypothetical and that other reduction strategies may exist as well.

c. “Core tools have been also recognized in Neumark-Nord 2 and Konigsaue [109]”: Königsaue

Chapter 7.2 Differentiation and imitation:…

a. “weight, empirical index of their reduction degree”: I think that weight is not a good and precise measure of reduction. How deal the authors with pieces manufactured from small blanks?

b. “Even Jöris [23] states that not all keilmessers are of the core-tools type but they”: I strongly suggest removing the word “Even” here or replace it by “also” or an equivalent. “Even” expresses a specific opinion about or an evaluation of Jöris here and, despite the long chronology vs. short chronology debate, hypotheses of Jöris are not analyzed/discussed in this paper.

Chapter 7.3 On the Keilmessergruppen/MMO…

a. “Within some open-air, short-term occupations, keilmessers and related artefacts can represent the whole assemblage, with the absence of core-reduction technologies (i.e. in Lichtenberg [18] or Zwolén [31])”: Pietraszyn 49a is a good example here as well.

b. “According to the chronological distinction by Joris [23], after a debated phase A,”, and the paragraph below: “Jöris”

Reviewer #2: While microscopic approach especially to use-wear makes great achievement on functional study of stone tools, macroscopic approach on lithic morphology with techno- and mechano-functional aspects is rare. In this regard, this is recognized as an epoch making paper in the field. The concept and research design is excellent. Analyses conducted in the paper and discussion are sufficient. Introducing TFS in comparison with conventional classification (typology) is effective to explain and interpret technological system. Fig.12 is so nice to represent differences between Keilmessers and scrapers. These series of analyses achieve new perspective which can overcome dichotomy of different paradigm: morpho-typology for cultural history and functional evaluation with quantified approach.

Nevertheless, if the original data related to 3D morphology (including angle of edges) is available, it would be more sufficient with more transparency and reproducibility. Additional description or schematic illustration for procedure and controls in 3D morphology would help understanding of readers.

Despite of this additional request, this paper is significant on establishing a novel methodology of lithic morphology in general, not in the specific field of European Middle Palaeolithic.

I am fully recommended to publish this paper.

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Reviewer #2: Yes: Atsushi Noguchi

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Techno-functional and 3D shape analysis applied for investigating the variability of backed tools in the Late Middle Paleolithic of Central Europe.

PONE-D-20-12918R1

Dear Dr. Delpiano,

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