Response to Reviewers
Comments from the Journal and the two reviewers are presented below, with our responses
in italics. The changes are also shown in a Word document with track changes. Line
and page numbers correspond to the annotated version of the manuscript [track changes
-> All markup (Show All Revisions Inline)]. All figures have been deleted from the
Word documents of the manuscripts.
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I have added the following in lines 177-179 (Pg. 6): “The described study complied
with all relevant regulations and the necessary permit (REF: SAH19/13092) was obtained
from KwaZulu-Natal Amafa and Research Institute.”
3. We note that you have referenced (i.e. Bewick et al. [5]) which has currently not
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detailed online in our guide for authors
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We have not referenced Bewick et al. and I am not sure what this is referring to.
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The Gateway to Astronaut Photography of Earth (public domain): http://eol.jsc.nasa.gov/sseop/clickmap/
Maps at the CIA (public domain): https://www.cia.gov/library/publications/the-world-factbook/index.html and https://www.cia.gov/library/publications/cia-maps-publications/index.html
NASA Earth Observatory (public domain): http://earthobservatory.nasa.gov/
Landsat: http://landsat.visibleearth.nasa.gov/
USGS EROS (Earth Resources Observatory and Science (EROS) Center) (public domain):
http://eros.usgs.gov/#
Natural Earth (public domain): http://www.naturalearthdata.com/
The image referred to in Figure 1 is an aerial photograph of the palaeosurface that
we took as part of this study using a drone. As such, there is no issue for us to
use it. We modified the figure caption to read:
Fig. 1. Geological setting of the Dave Green palaeosurface. A) Simplified geological
map of the main Karoo Basin. Position of the study area is indicated. B) Aerial photo
of the palaeosurface (taken by AK). C) Stratigraphic log measured along the Rensburgspruit.
Figure 9 (now Fig. 10) included in image of a saltwater crocodile on a tidal flat
and we were unable to get the necessary permission to use it. As such, I have modified
the figure to include a photo of an impression of an alligator for which I have obtained
permission from the photographer, Gale Bishop. I have uploaded the completed Content
Permission Form.
Caption of Fig. 10 reads: “Fig. 10. Comparison of Impression 2 from the palaeosurface
(A) with a present-day body impression and trail of Alligator mississippiensis on
the foreshore at St. Catherines Island, Georgia, United States (B). Photograph courtesy
of St. Catherines Island Sea Turtle Program, Gale A. Bishop and modified with permission
from [92]. C) A rhinesuchid temnospondyl such as Laccosaurus or Uranocentrodon is
probably the tracemaker. Scale bar = 30 cm (A and B).
5. Please review your reference list to ensure that it is complete and correct. If
you have cited papers that have been retracted, please include the rationale for doing
so in the manuscript text, or remove these references and replace them with relevant
current references. Any changes to the reference list should be mentioned in the rebuttal
letter that accompanies your revised manuscript. If you need to cite a retracted article,
indicate the article’s retracted status in the References list and also include a
citation and full reference for the retraction notice.
We have not cited any retracted papers.
Some references that have been added include:
[61] Marchetti L, Belvedere M, Voigt S, Klein H, Castanera D, Díaz-Martínez I, et
al. Defining the morphological quality of fossil footprints. Problems and principles
of preservation in tetrapod ichnology with examples from the Palaeozoic to the present.
Earth-Sci Rev. 2019;193: 109–145. doi:10.1016/j.earscirev.2019.04.008.
[75] Carmona N, Bournod C, Ponce JJ, Cuadrado D. The Role of Microbial Mats in the
Preservation of Bird Footprints: A Case Study from the Mesotidal Bahia Blanca Estuary
(Argentina). In: Noffke N, Chafetz H, editors. Microbial Mats in Siliciclastic Depositional
Systems Through Time. SEPM Society for Sedimentary Geology; 2011. pp. 37–45. doi:10.2110/sepmsp.101.037
[76] Marty D, Strasser A, Meyer CA. Formation and Taphonomy of Human Footprints in
Microbial Mats of Present-Day Tidal-flat Environments: Implications for the Study
of Fossil Footprints. Ichnos. 2009;16: 127–142. doi:10.1080/10420940802471027
[Note: HTML markup is below. Please do not edit.]
Reviewers' comments:
Reviewer #1: This is an interesting and well-executed study, describing and interpreting
some remarkable body traces attributed to amphibians. Nevertheless, some parts of
the manuscript can be improved. Some additional information on coordinates and stratigraphy
should be provided. Some close-ups of the circular tracks should be added to the figures.
The interpretation of the trace 2 should be expanded, and labels for the single tracks
added. The morphology of the body traces shluld be compared with those already described
from the Palaeozoic, a new ichnotaxonomy can be proposed. In general, the interpretation
in several part can be more tentative. The 3D models could be deposited in an online
repository. All the comments are in the attached pdf
Best regards,
Lorenzo Marchetti
Comments from the PDF:
Line 63 (Pg.1): all citations should go in chronological order in the text, unless
this journal says otherwise
The reference style has been changed to follow the guidelines of PLOS ONE.
Line 64 (Pg. 2): better "reptiles including dinosaurs" or "dinosaurs and other reptiles"
Changed “dinosaurs and reptiles” to "dinosaurs and other reptiles"
Line 66 (Pg. 2): I agree on the body traces, but not on the pes and manus footprints
because they do not show anatomical detail. Please rephrase. For an extensive discussion
about trace preservation, see: Marchetti, L., Belvedere, M., Voigt, S., Klein, H.,
Castanera, D., Díaz-Martínez, I., ... & Farlow, J. O. (2019). Defining the morphological
quality of fossil footprints. Problems and principles of preservation in tetrapod
ichnology with examples from the Palaeozoic to the present. Earth-Science Reviews,
193, 109-145.
Changed “remarkably well-preserved” to “remarkable”
Line 69 (Pg.2): [regarding the “preserving”] better "generated by" or similar
Changed “preserving” to “recording”
Line 85 (Pg. 2): [locality of the site] Please add coordinates
Added coordinates in line 85 “(S28.967122°, E29.987366°)”
Line 102 (Pg. 3): [Regarding the Waterford Formation] could you provide the thickness
of this formation? Also information on its age would be important. And please specify
if the contact with the overlying Balfour Formation is conformable
Inserted “Within the study area, the Waterford Formation is at least 140 m thick and
is considered to be Wuchiapingian in age (Groenewald 2021).” in lines 121-122
Inserted “conformably overlying” before “lower Balfour” in Line 106
Inserted “(Lopingian)” between “late Permian” and “Daptocephalus” in line 166
Line 142 (Pg. 4): [Heading “Palaeontology”] of the locality
Changed to “Local palaeontology”
Line 152 (Pg. 4): [attributed to small-to-medium sized dicynodont trackmakers] on
which bases?
Added “, based on track morphology and because dicynodonts are the most commonly represented
group in the body fossil record,” after “trackmakers” in lines 152-154.
Deleted “them” in line 154
Line 155 (Pg. 5): [Regarding fossils] here it would be important to know in which
formation these fossils were found, and if they were stratigraphically above or below
the palaeosurface, if possible
Added the following after “Fig. 3).” in line 158: “Plant fossils below the palaeosurface
are generally more fragmentary than those above it. Vertebrate fossils below the palaeosurface
are restricted to isolated and fragmented fish bones and scales, whereas vertebrate
fossils recovered from the Balfour Formation by us and previous workers on the farm
van der Merwe’s Kraal 972 include a partial rhinesuchid amphibian skull (BP/1/7858;
c.f. Laccosaurus) and fragmentary dicynodont material.”
Line 194 (Pg. 7): it would be good to make the 3D models available in a public digital
repository
The 3D models have been uploaded to Morphosource
Line 203 (Pg. 8): [Regarding “The Dave Green ichnofossils are”] perhaps better to
add "palaeosurface"
Inserted “palaeosurface” after “Green”
Line 205 (Pg. 8): [Regarding “upper part”] better uppermost or topmost
Changed “upper” to “uppermost”
Line 217 (Pg. 8): [Regarding “upper”] see comment above. The fact that the palaeosurface
is at the boundary between the two formations should be better remarked
Because we have stated uppermost in line 205, I do not think it is necessary to repeat
“uppermost” here as well. In the Abstract, we state that the palaeosurface is situated
“immediately below the paleaoshoreline of the Ecca Sea” (Line 50), and again under
Geological background (line 92), we state that the palaeosurface is situated “immediately
below the Ecca-Beaufort contact”
Line 224 (Pg. 8): [Referring to “Palaeocurrent readings”] which is the ripple strike
orientation?
Palaeocurrent for asymmetrical ripples is perpendicular to strike, in the direction
of the lee side. Have included “, with ripple crest strike orientation of 168-348º,”
after “asymmetrical ripples”
Line 229 (Pg. 9): [Referring to “with a strike orientation of 278°”] which is the
current direction?
Symmetrical ripples do not indicate palaeocurrent direction. I have changed the strike
orientation to “98-278º”
Line 228 (Pg. 9): [Referring to “Several medium-sized depressions”] are these trace
fossils or sedimentary structures?
Here we do not specify as it is uncertain. The origin of the depressions is discussed
in lines 377-382 and we state (line 380) that they “could have formed as erosional
depressions, or possibly footprints,”
Line 233 (Pg. 9): [Referring to “smaller, [sub]circular depressions,”] please specify
that these are ichnofossils
Line 233: Changed “circular” to “subcircular”
Changed line 234-236 to read “We consider these to represent trackways with poor morphological
preservation and describe them further below under Subcircular depressions.”
Line 240 (Pg. 9): [Referring to “in three groups”] please specify that is based on
morphology and arrangement of the traces
Added “based on the morphology and arrangement of the traces” after “groups”
Line 271 (Pg. 11): [Referring to “15 round depressions”] please provide the diameter
Changed lines 272-275 to read “These depressions, eleven of which are alongside impression
2A and four are alongside impression 2B, have diameters between 33 and 63 mm and some
have smooth expulsion rims.”
Line 275 (Pg. 11): [Referring to “lack of morphology”] please explain this in terms
of preservation
Lines 275-277 now read: “The footprints have poor morphological preservation (M-preservation
grade 0 using the scale of Marchetti et al. (2019a)) that makes it difficult to distinguish
manus from pes.”
Line 279 (Pg. 11): [Referring to “A similar distance separates the posterior from
the anterior pair of footprints in impression 2A.”] how can you tell? Impression 2A
has 11 associated footprints. Perhaps specify that a similar distance can be measured
between supposed posterior and anterior pairs taking into account progression while
generating the body trace, which in fact results longer than 2B. You should add numbers
to the pairs in the figure and refer to them (also provide measurements of gleno-acetabular
distance, stride, pace angulation, trackway width)
Included “(RP3-RM5 and LP3-LM4)” after “respectively” in line 279
Lines 279-282 now read: “A similar distance separates the supposed posterior and anterior
pairs of footprints, taking into account progression while generating the body trace
(LP1/RP1-LM2/RM2 or LP2/RP2-LM3/RM4), in impression 2A (Fig. 7).”
Fig. 7 has been modified following the suggestions, including adding numbers to the
impressions and footprints and marking the gleno-acetabular distance.
Line 300 (Pg. 12): [Referring to “swim”] interpretation later
Deleted “swim”
Line 302 (Pg. 12): [“Circular depressions”] please add close-ups of these structures,
they are not visible in the current figures
Changed “circular depressions” to “Subcircular depressions”
Replaced “closely grouped” with “Subcircular” in Line 241
Modified the paragraph describing these and have also added a new figure, Figure 8.
Lines 303-313 now read: “Several groupings of smaller, subcircular and blob-shaped
depressions occur across the palaeosurface. Three such groupings, indicated in Fig.
5 as “Smooth area with depressions” since the area surrounding the depressions is
often smooth and not rippled, are: 1) a “corridor” ~0.9 m wide that crosses the surface
from the western to eastern side (Fig. 4G and Fig 8A-E); 2) a concentration just north
of the present-day island; and 3) a higher density of these depressions preserved
in the northwestern part of the surface (Fig. 8). The depressions vary in size and
shape with diameters ranging from 10–15 cm. The bottom of many of the depressions
is sculpted with asymmetrical ripples and little-to-no morphological details are preserved.”
Lines 332-333 (Pg. 13): [“and lack the typical sinuous shape normally associated with
fish trails”] this should go in the discussion
I have deleted this half of the sentence. In the discussion it already says in lines
477-478 “While most of the traces are straight and lack the sinusoidal pattern characteristic
of Undichna,”
Added “of” to the sentence between “most” and “the” in lines 477-478
Line 364 (Pg. 14): [Referring to the second “which”] with?
This is an error and I have deleted “which”
Line 365 (Pg. 14): [“indicate that the palaeosurface was submerged at the time that
the traces were made”] please be more tentative here, the Undichna assignment is not
certain and the surface may have been flooded again
The assignment to Undichna is also quite certain for some of the linear traces, e.g.
LT1 and the Undichna unisulca trace shown in Fig. 9I.
Changed to: “indicate” to “suggests”
Line 366 (Pg. 14): Replace “traces” with “large impressions”
Done
Line 383 (Pg. 15): [Referring to “The smoother, non-rippled areas of the surface are
possibly where a biofilm or microbial mat was growing on the sand in a shallow water
environment…”] is it possible that these areas were simply not submerged or deep enough
for the ripple formation? Interestingly, the supposed tracks are in these areas. Also,
if microbial mats were present, there should be sedimentological evidence such as
elephant skin structures
Areas with smooth, non-rippled surfaces adjacent to rippled ‘erosional patches’ are
commonly observed on tidal flats (Cuadrado et al. 2011) and we feel we have adequately
shown this with the photographs in Figure 4.
CUADRADO, D. G., CARMONA, N. B. & BOURNOD, C. 2011. Biostabilization of sediments
by microbial mats in a temperate siliciclastic tidal flat, Bahia Blanca estuary (Argentina).
Sedimentary Geology 237(1–2), 95–101. doi: 10.1016/j.sedgeo.2011.02.008
We have also added the following (Lines 387-390): “In parts of the palaeosurface,
the surface weathers with distinctive quadrangular chips. These resemble ‘mat chips’
produced by the erosion of modern microbial mats by waves and currents (Cuadrado et
al. 2011) and further support the presence of a microbial mat on the surface.”
Line 390-391 (Pg. 15): about trace preservation in microbial mats, see: Marty, D.,
Strasser, A., & Meyer, C. A. (2009). Formation and taphonomy of human footprints in
microbial mats of present-day tidal-flat environments: implications for the study
of fossil footprints. Ichnos, 16(1-2), 127-142.
I have now cited this paper in lines 392 and 443-446
Line 398 (Pg. 16): you can consider doing a new ichnotaxonomy of the large impressions.
Also, a morphological comparison with the other supposed Paleozoic amphibian body
impressions should be done
Because there is, at this stage, not a physical cast of the specimen that can be deposited
in a collection and easily accessed for study by others, we have decided not to do
the full ichnotaxonomy yet. We have tried to make casts but because the structure
is large and very shallow it was not possible to make a cast which reliably reflected
the morphology. A full morphological comparison is also something that will be done
at a later stage.
Lines 429-430 (Pg. 17): add the ichnospecies name to both these ichnogenera [Hermundurichnus
and Sauropleura]
Done
Lines 429: please indicate in which instances your traces differ from these ichnospecies
The most notable difference, size, has already been stated in lines 435-436: “All
these examples are, however, as much as 10 times smaller than the impressions reported
here.”
Line 464 (Pg. 18): [dicynodont therapsids as most likely trackmakers] please add an
explanation for this, and references for dicyndont tracks found in the Balfour Formation
Modified the paragraph so it now reads: “The morphology of the traces provides little
information on the identity of the trackmaker but the most likely candidates are dicynodont
therapsids. Trackways made by groups of dicynodonts have been reported previously
from the Karoo (de Klerk 2002; MacRae 1990), and they are the most common animals
of the required body size recorded by body fossils from the area.”
Line 518 (Pg 20): [“The fact that many of the impressions are isolated and have no
connecting trackways or swim traces (e.g., the gap between Impressions 2 and 3) is
interpreted as evidence for subaqueous activity (Hasiotis et al. 2007)”] it can also
be a preservational bias due to different mechanical properties of the substrate in
different areas at the time of the impression
Added the following two sentences (lines 522-525): “An alternative interpretation
is that the gaps resulted from a preservational bias due to different mechanical properties
of the substrate in different areas at the time of registration. However, because
of the lack of disturbance or deformation of surface between impressions, especially
to the ripple crests, this is considered less likely.”
Line 535 (Pg 21): [“Changes in the footprint trackway associated with impressions
2A and 2B could therefore reflect a shift from bottom walking, with a similar but
more variable stride length to terrestrial pedestrianism in 2A, after which the trackmaker
pushed up and floated a short distance before settling on the bottom – hence only
leaving four footprints associated with Impression 2B.”] or it was all walking and
the other tracks were just not preserved
Line 539: Inserted “It is also possible that both impressions were created through
walking but that some of the tracks were just not preserved.” after “Impression 2B.”
Line 563 (Pg.22): [“However, the absence of well-defined ripples in most of the body
impressions in conjunction with the swim traces indicates that the current was no
longer strong enough to overprint the traces with new ripple marks before the surface
was buried and preserved by the overlying strata.”] or the water was too shallow/absent
Added “The lack of ripple marks could also suggest that the water was too shallow
or absent at the time registration, although, if this were the case, we would expect
to see more footprints associated with the traces.” at the end of the paragraph (Line
569-571)
585-596: this part is very interpretive, consider editing, reducing or removing
I have edited this paragraph,and it now reads (Line 572-585): “Some of the traces
preserve sharp turns or changes in direction, e.g., Impressions 3, 4, and 5. No observable
footprint impressions or disturbances to the adjacent rippled surface are associated
with the turns as observed in other amphibian swimming traces (Turek 1989), and the
slightly enlarged area anterior to the tail implies that the hind limbs were tucked
against the body. It is possible that the animal used its front legs to help steer
in a manner similar to younger crocodiles (Seebacher et al. 2003) and that they did
not touch the substrate. Another possibility is that the animal did not use its legs
at all while swimming, as seen in larger crocodiles (Seebacher et al. 2003), but they
were used only when the animal touched the substrate, or while bottom walking (Farlow
et al. 2018b; Mujal & Schoch 2020). While a direction of travel cannot be determined
for LT1, it is worth noting that Impressions 1-4 run almost parallel to LT1 (Fig.
5). If LT1 is taken to have been travelling north-south before turning and heading
west-east, this could suggest that the tracemaker was actively following the fish,
and that the traces record some hunting behaviour. Furthermore, the point where the
smooth trace and LT1 are closest together, is near the sinuous section, i.e., at which
point the fish put in a burst of speed to escape.”
I also edited lines 325-335 to follow the same direction of travel, i.e., start in
the north. Figure 9 has also been updated to reflect these changes. This paragraph
now reads: “The first linear trace (LT1) consists of a paired trace that can be followed
southwards from the northwestern edge of the surface, where it either overprints or
is overprinted by Impression 1 (Fig. 9A and B). It makes a sharp turn just south of
Impression 7 (Fig. 9C and D) and can be followed eastwards across the surface to the
eastern margin of the palaeosurface (Fig. 9E). The individual traces are ~1 cm wide
and the paired traces are ~35 cm apart. Except for a short, sinuous section near Impression
4, the trails are relatively straight. In the sinuous section (Fig. 9F), the trails
have a wavelength of 36–39 cm and an amplitude of 5 cm.”
Figure 4G: add close-ups
Created a new figure, Fig. 8, which shows the subcircular depressions better.
Fig 7: [scale] better in cm
The figure has been modified and now includes a scale bar of 50 cm
Fig 7: add track numbers and body trace letters
Done
Reviewer #2: Dear colleagues,
I have carefully read and reviewed the manuscript, which deals with conspicuous impressions
produced by a tetrapod (an amphibian, as the authors thoroughly discuss) on a large
palaeosurface from the upper Permian of the Waterford Fm. (Karoo Basin, South Africa).
The reported traces are impressive and very interesting, adding valuable knowledge
on the locomotion of amphibians (and particularly rhinesuchids) and their palaeoecology.
In addition, the authors carried out a very detailed sedimentological study allowing
for a detailed palaeoenvironmental reconstruction.
The manuscript is very well written and the figures are of good quality and very informative.
I think this work deserves to be published after a minor revision is undertaken. I
have only found minor issues to correct and/or clarify in the text and a few in the
figures (for the latter only to show some figured elements better). I annotated all
my comments and suggestions in the attached PDF by using the Adobe Reader Comment
tools.
The only major point to consider in the text is on the interpretation of the order
of impression of some of the traces. It is claimed that the traces described as "Circular
impressions" were made before the temnospondyl traces (see comment on page 16 of the
manuscript, lines 394-394). However, I can't see this clearly with the given data.
The authors show provide further discussion/evidence for this. In any case, I still
see this as a minor point because it doesn't change the main message of this research.
There is another point that I didn't comment in the PDF, but that it might be interesting
to mention in the manuscript, and in any case only if the authors find this appropriate.
As the authors clearly demonstrated, the palaeosurface described was formed in a tidal
flat or a lagoon, i.e., a coastal-marine setting. Just as a suggestion, the authors
could add a short discussion on the fact that temnospondyl traces are found in such
a setting, because usually (though not exclusively) temnospondyls are reported from
freshwater settings. Of course, this should not change any content of the manuscript,
which I find very good, it would only be adding some palaeoecological remarks on rhinesuchids
roaming a coastal-marine setting.
I hope that my review is useful to the authors, for any doubt, I would be glad to
give further feedback to the authors. I am looking forward to seeing this work published.
Best regards,
Eudald Mujal (Staatliches Museum für Naturkunde Stuttgart)
Regarding the marine setting – The lower Ecca Group is generally accepted as having
been deposited under marine conditions, whereas the upper Ecca Group was deposited
under brackish-to-fresh water. As such, we have changed “marine” in line 365 to “water”
and added the following sentence after “(de Gibert & Benner 2002).” in line 366: “The
water was likely brackish-to-fresh based on the conclusions of several studies using
trace elements from the upper Ecca Group (Muntingh 1997; Veevers et al. 1994; Zawada
1988).”
Comments from the PDF:
Line 49 (Pg. 1): [“a late Permian”] “an upper”
We have left this unchanged. The “late” applies as a chronological rather than a stratigraphic
term. The palaeosurface is not considered upper Permian stratigraphically, since it
is at the base of the Beaufort Group in KwaZulu-Natal Province. Because the palaeosurface
is late Permian in age, we have used late Permian.
Line 55 (Pg. 1): Replace “marks” with “grooves”
Changed to: “The sinuous shape of some of the traces”
Line 56 (Pg. 1): Change trackmaker to tracemaker
Done
Line 78 (Pg. 2): [“photogrammetry scans”] I think this should rather be "surface scans".
Changed to "surface scans"
Line 79 (Pg.2): [“trackmaker”] Since most of the impressions you are describing are
not tracks (understood as the imprints produced by autopodia), I would write "tracemaker"
instead of "trackmaker". In fact, I see that later in the text you use "tracemaker".
Done. Also changed in line 80
Line 89 (Pg. 3): replace “late” with upper
Left unchanged. See response for line 49
Line 101 (Page 3): [Fig 2 caption] Replace “manuscript” with “text”
Done
Line 105 (Pg. 3): “f” lowercase in “Formation”
Done
Line 120 (Pg. 4): replace “suggest” with “suggested”
Changed “suggest” to “showed”
Line 138-141 (Pg. 4): [“The depositional environment for the Balfour Formation in
the northeastern main Karoo Basin has been interpreted as high load meandering river
environments (Botha & Linström 1977, 1978; Green 1997; Groenewald 2021, 1989, 1990;
Groenewald et al. 2022; Johnson et al. 2006; Muntingh 1989, 1997).”] This sentence
is the nearly the same as the anterior one. Please delete one of the two.
Deleted the second sentence
Line 137 (Pg. 4): Replace “environments” with “systems”
Done
Line 157 (Pg. 5): [D.G.] insert “P.”
Changed to DPG
Line 163 (Pg. 5): delete “c.f.”
Unchanged. The identity of BP/1/7858 is tentative
Changed “an almost complete rhinesuchid” to “partial rhinesuchid” as BP/1/7858 comprises
only the posterior portion of the skull and the snout is missing.
Line 165 (Pg. 5): [“KZN”] Is this KwaZulu-Natal? If so, write this instead of the
abbreviation (not used anywhere else in the text).
Changed to “KwaZulu-Natal
Table 1: Write the facies codes in italics.
Done
Table 1: insert “,” between “deposition” and “e.g.” [in the interpretation of “Sm”]
Done
Table 1: [“couple” in the interpretation of “Sm”] Should this be "could"?
Corrected to “could”
Table 1: [“Fl” in description of “Fm”] also in italics
Done
Line 181 (Pg. 7): Change “which” to “that”
Done
Line 186 (Pg. 7): [“photogrammetry”] I think this should rather be "surface scanning".
Changed “white-light source photogrammetry” to “surface scanning”
Lines 183-187 “Consequently, we used high-resolution scanning to digitise and accurately
record the palaeosurface. Combining surface scanning and aerial images, we were able
to accurately portrait the surface trackway.” have been combined and rewritten and
now reads (Lines 183-185) “Consequently, we combine high-resolution surface scanning
and aerial images to digitise and accurately record the surface.”
Line 194 (Pg. 7): Above you mentioned photogrammetry was performed, but here it is
not mentioned, I guess before you meant surface scanning. Please either add information
on any photogrammetric models you did or remove the references to photogrammetry.
All references to photogrammetry have been removed.
Added “and ParaView v. 5.10.1 (https://www.paraview.org/)” at the end of line 200
Line 226 (Pg. 9): [“Gyrochorte-like invertebrate traces are present on the northwestern
part of the surface (Fig. 4C and D).”] I can't identify the Gyrochorte-like traces
in the cited subfigures. Could you please point them (e.g., with arrows) in the photographs?
I have modified the photo in 4D and placed arrows to show the invertebrate traces
Line 255 (Pg. 10): Upper case (as done elsewhere for "Impression/s #number").
Done. Also in Line 257
Caption Fig. 6: [“In parts 1–5: scale] Should this be 1-6? Otherwise provide the length
of the scale bar in 6
Corrected to “1–6”
Caption Fig.7 First letter capitalized [for “impression”] (as done in the text).
Done
Table 2: I would put both length and width in mm, so that they both are in the same
units.
Put them both into cm in the table. In the text the measurements remain unchanged.
Table 2: If possible/relevant, could you add also dimensions for Impression 6? I suggest
this mainly because it is shown in Fig. 6.
We do not have the measurements for this one as the measurements were taken off the
models produced by the scans and Impression 1 and 6 were not scanned.
Line 284 (Pg.11): Delete “-“ in “Trace-maker”
Done. Also done elsewhere in the text
Line 291 (Pg. 12): Do you mean "faint" here?
Replaced “feint” with “faint”
Line 304 (Pg. 12): Insert “of” before “such”
We have left unchanged as “three of such” does not make sense.
Line 303 has been changed and now reads: “Several groupings of smaller, subcircular
and blob-shaped depressions occur across the palaeosurface.”
Caption Fig. 8[ now 9]: Delete “pairedlarge”
Done
Caption Fig. 8[now 9]: Add the length of the hammer here please (e.g., Hammer (30
cm long) for scale). And move this to the end of the caption, since the hammer appears
in several photos.
Done
Caption Fig. 8 [now 9]: The arrows are not very visible, they should be (slightly)
larger and/or in another colour (e.g., white, or with black outline and white infill).
Arrows have been modified in Figure 9I and are now more visible
Inserted new picture in Figure 9 (9B) which shows the trace crossing Impression 1.
Line 357 (Pg. 14): Add an “h” to “Undicna”
Done
Line 364 (Pg. 14): Delete second which in sentence
Done
Line 390-391 (Pg. 15): [comment] See also Marty et al. (2009: Ichnos), who discussed
on the different preservations of tracks in microbial mats.
Marty, D., Strasser, A., Meyer, C.A., 2009. Formation and taphonomy of human footprints
in microbial mats of present-day tidal-flat environments: implications for the study
of fossil footprints. Ichnos 16, 127–142.
These lines have been modified and now read: “Tracks and traces require the substrate
to be ‘just right’ in order to be preserved (Falkingham et al. 2014). Under certain
conditions, the presence of microbial mats have been shown to favour or enhance the
preservation of footprints (Carmona et al. 2011; Marty et al. 2009) and microbial
mats are commonly associated with fossil trackways, including in the Karoo Basin (Marsicano
et al. 2014; Sciscio et al. 2016, 2020; Smith 1993).”
Line 393 (Pg 15): Add “Basin” after “Karoo”
Done. Also added “main” before Karoo in the same line.
Line 398 (Pg. 16): [“impressions”] italics
The headings are now formatted according to the style of PLOS ONE (14 pt and Bold)
Line 404-405 (Pg. 16): [“Early Jurassic”] Change “Early” for “Lower”
Done
Figure 9 [now 10]: It might be better to add a letter (B) in the photograph of Impression
2, separating it from the subfigure A. In this sense, B should be then C.
Done
Caption Figure 9 [now 10]: [“impression”] Upper case
Done
Figure 9 [now 10]: As a whole, I like this figure a lot! I would add a scale bar in
B [C in the updated figure].
C is not drawn to scale
Caption Figure 9 [now 10]: [“trace-maker”] delete “-”
Done
Line 421 (Pg. 16): Change “trackmaker” to “tracemaker”
Done
Line 422 (Pg. 16): Replace “late” with “upper”
We have left this unchanged. The “late” applies as a chronological rather than a stratigraphic
term. The palaeosurface is not considered upper Permian stratigraphically, since it
is at the base of the Beaufort Group in KwaZulu-Natal Province. Because the palaeosurface
is late Permian in age, we have used late Permian.
Line 440 (Pg. 17): [“trace maker”] Without space between the two words.
Done
Lines 447 (Pg. 17): As before, please check also Marty et al. (2009), as well as Carmona
et al. (2011), who also focused on the taphonomy of tracks on microbial mats.
Marty, D., Strasser, A., Meyer, C.A., 2009. Formation and taphonomy of human footprints
in microbial mats of present-day tidal-flat environments: implications for the study
of fossil footprints. Ichnos 16, 127–142.
Carmona, N., Bournod, C., Ponce, J.J., Cuadrado, D., 2011. The role of microbial mats
in the preservation of bird footprints: a case study from the mesotidal Bahia Blanca
estuary (Argentina). In: SEPM Special Publications, 101, pp. 37–45. https://doi.org/ 10.2110/sepmsp.101.037.
These references have been included and lines 444-446 have been modified to read:
“The lack of morphology in the associated footprints could also be the result of the
interplay between the algal mat and substrate properties (Carmona et al. 2011; Marty
et al. 2009). Alternatively, post-registration growth of the microbial mat on the
substrate could have resulted in the loss of morphological detail over time (Carmona
et al. 2011; Cuadrado et al. 2012; Gerdes 2007; Marty et al. 2009; Reineck & Singh
1975, 1980; Schieber 1998; Selley 1985).”
Line 459 (Pg. 19): [“liquefied”] change to “liquified”
Both spellings are correct. Left unchanged
Line 462-463 (Pg. 18): [“This indicates that these trackways were probably made before
the temnospondyl traces.”] I am not totally convinced. With what I see in Fig. 4G,
the "corridor" of footprints is not smoothed/overprinted by any structure, and it
seems that Impressions 2 and 3 are connected by a smooth trace, as shown in Fig. 5.
Therefore, I would expect that the depressions in the corridor at the height of Impressions
2 and 3 should be more smoothed than the others (i.e., overprinted by the temnospondyl
tracemaker). In this sense, the trackways you interpret should have been imprinted
after the temnospondyl traces. Maybe it is a matter that I don't see this well in
the figures. If you have a close up of this region, it would be worth it to figure
it.
The area is now better figured in a new figure (Figure 8)
It is also not clear that the trackway has overprinted a swim trace, as one cannot
be picked up on either side of the “corridor”. Our main argument for the order of
the traces i.e., that the trackway is older, is because there are ripples in some
of the footprints but not in the amphibian body traces. This is explained in Lines
459-462. It is not definite and for that reason we have said that the trackways were
probably made before the impressions (line 462).
Line 477 (Pg. 19): Insert “of” after “most”
Done
Line 482 (Pg. 19): Do some of the more linear traces align with the palaeocurrents?
If so, this could support the hypothesis of a stick drifting and dragging along the
sediment. It would be worth it to mention the relationship in orientation between
these traces and the palaeocurrents.
Modified the sentence to read: “It is also possible, however, that some of the more
linear examples such as LT2 and LT3, which have a similar orientation to the palaeocurrent
direction, were created by a stick drifting and dragging along the sediment, thereby
forming a pseudo trace fossil (R. Gess, pers. comm. 2015).”
Line 518 (Pg. 20): Please see comment in page 16 (lines 393-394) above. Could it be
that the traces aren't connected because the circular structures interpreted as trackways
overprinted the connection area?
That may be the case between Impressions 2 and 3, but what about between Impressions
1 and 2, and 5 and 6 where there are areas with no subcircular depressions.
Line 530 (Pg. 21): Please consider to cite here Farlow et al. (2018b) and Mujal &
Schoch (2020), who also discussed this fact.
Done
Line 553 (Pg.22): Change “trackmaker” to “tracemaker”
Done
Lines 558, 559, and 572 (Pg. 22): Capitalise “I” in “impression”
Done
Additional changes:
Line 67: Changed “Estcourt district” to “uThukela District”
Line 93: changed “recording” to “, which records”
Line 107: Inserted “Formation” after “Balfour” and moved the “)” from behind “Estcourt”
to after the citations
Line 151: changed “P” to “p” in “palaeosurface”
302 (Pg. 12): Here, and throughout the text, changed “circular depressions” to “subcircular
depressions” or “subcircular to blob-shaped”
Lines 378-379: Deleted “similar to the oscillatory ripples from other parts of the
section (Groenewald 2015, 2021), but”
Line 396: Corrected spelling of “mineralization” to “mineralization”
Lines 487-491: Inserted “Because of this, and in contrast to many present-day and
fossil examples of crocodilian and temnospondyl trackways, which typically comprise
a trackway with a central tail or belly drag (Cisneros et al. 2020; Farlow et al.
2018a; Marsicano et al. 2014; Milàn & Hedegaard 2010), the impressions and traces
on the Dave Green palaeosurface lack associated footprints or scratch marks, with
the exception of Impression 2.”
Lines 541-547: Moved paragraph: “Impressions 2 and 3 are relatively close together
and appear to follow on from one another (Figs. 2 and 5). As such, we consider these
to have been formed by the same individual. The direction of movement can be determined
by looking at the tail to body direction. For example, impression 2 indicates an animal
that was moving in a south-easterly direction, as evinced by the tail thickening in
the body direction as well as the more pronounced expulsion rim along the posterior
margin of some of the footprints, indicating the direction that the animal pushed
against the substrate.” earlier in the text. It is now between lines 511-517.
Lines 515-516: Changed “slightly bulged area behind” to “more pronounced expulsion
rim along the posterior margin of”
Line 623: Changed “for” to “during” and “goes” to “go”
Line 624: inserted “We are grateful to Academic Editor Prof. Jörg Fröbisch for handling
our manuscript, and to Dr Lorenzo Marchetti and Dr Eudald Mujal for their constructive
reviews.”
Line 626-628: Changed to read:” Opinions expressed and conclusions arrived at, are
those of the authors only and do not necessarily reflect those of are not necessarily
to be attributed to the NRF, the CoE-PalGENUS, or to PAST, or the European Union.”
Line 636: Changed “JH” to “PJH”
- Attachments
- Attachment
Submitted filename: Response to Reviewers.docx