Review Reports - Paired Flowers of Core Eudicots Discovered from Mid-Cretaceous Myanmar Amber

Round 1

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

This is an interesting paper on angiosperm flowers from the Myanmar amber. Although documented in detail, there are still more details needed for its full understanding.

The authors should decide if the plant is interpreted as a eudicot. If so, pentamerous symmetry is expected (as depicted in the floral diagram) and therefore they should re-shape the generic diagnosis. Fossils are not always completely preserved, and we need some degree of reconstruction. (Four stamens in positions as depicted are not natural, they are evidently five, the same for petals).

In the diagnosis the authors state: “Pistil solitary, tricarpellate, with bifurcated style”. However, three carpels are not depicted in the floral diagram.

The authors should provide more details to the position of the ovary and placentation. If this is not clearly shown, their interpretations are rather vague.

A bifurcated style, if there are three carpels, does not fit. In Fig. 2 it seems to be a fragment of the third part of the style.

The description, illustration and reconstruction of each character need more care. The authors should focus on diagnostically important characters. Illustration of hairs is secondary.

In the discussion with modern families, I miss Ericaceae.

What is completely missing is the discussion with fossil taxa. It is evident that the authors do not know or ignore essential literature of the topic (e.g. Friis et al. 2011, Knobloch and Mai 1986). In terms of comparison, I recommend taking in account ericalean reproductive structures such as Actinocalyx, Paradinandra, although being hypogynous and other similar fossils (Discoclethra).

Smaller issues:

Line 34: use better wording instead of “we report a new pair of flowers”

Line 92 – wording “Each locule is ellipsoid” should be changed to “Each locule is ovoid”.

Line 184: Statement “core eudicots that occurred 99 million years ago” needs a reference.

Comments on the Quality of English Language

English may be improved.

Author Response

Comments and Suggestions for Authors

This is an interesting paper on angiosperm flowers from the Myanmar amber. Although documented in detail, there are still more details needed for its full understanding.

The authors should decide if the plant is interpreted as a eudicot. If so, pentamerous symmetry is expected (as depicted in the floral diagram) and therefore they should re-shape the generic diagnosis. We do not understand how to. Please be specific, otherwise we cannot do anything. Fossils are not always completely preserved, and we need some degree of reconstruction. (Four stamens in positions as depicted are not natural, they are evidently five, the same for petals).

Reply: Thanks for your suggestion. However, we are not allowed to arbitrarily reconstruct the flower as we wish or as it “should” be. As a palaeobotanist, we should restrict us from mixing our imagination into our data. We prefer to represent as it is. What you see is what you get. As for readers and other botanists, they can base their judgement and imagination on our truthful data. This is their freedom, not ours.

In the diagnosis the authors state: “Pistil solitary, tricarpellate, with bifurcated style”. However, three carpels are not depicted in the floral diagram.

Reply: We did it in the right of Fig. 2j. Pleae double check.

The authors should provide more details to the position of the ovary and placentation. If this is not clearly shown, their interpretations are rather vague.

Reply: The image of ovary has been shown as highlight part in Figs. 2d, f, g, 3k. However, restricted by the current material, we are not sure about the placentation. We prefer to representing the data as what it is.

A bifurcated style, if there are three carpels, does not fit. In Fig. 2 it seems to be a fragment of the third part of the style.

Reply: We failed to confirm this idea. Therefore, we did nothing in this term. By the way, plants do follow our reasoning and expectation.

The description, illustration and reconstruction of each character need more care. The authors should focus on diagnostically important characters. Illustration of hairs is secondary.

Reply: We do whatever we can to document the truth. If a character is not preserved, we cannot say anything about it. On the contrary, if we see a character, we document it, no matter it is important or not. Being important or not, it is man-made judgement that may change on different occasions.

In the discussion with modern families, I miss Ericaceae.

Reply: Thanks. We have added this in the comparison.

What is completely missing is the discussion with fossil taxa. It is evident that the authors do not know or ignore essential literature of the topic (e.g. Friis et al. 2011, Knobloch and Mai 1986).

Reply: We have referred Friis book, and compared our fossil with Actinocalyx and Paradinandra, according to this suggestion. In terms of comparison, I recommend taking in account ericalean reproductive structures such as Actinocalyx, Paradinandra, We compared with these two taxa in the newer version. although being hypogynous and other similar fossils (Discoclethra). We cannot locate the original information about this taxon. Friis book has little information, therefore we gave up.

Smaller issues:

Line 34: use better wording instead of “we report a new pair of flowers”

Reply: Yes, we have deleted the word “new”.

Line 92 – wording “Each locule is ellipsoid” should be changed to “Each locule is ovoid”.

Reply: Yes, we have replaced the word.

Line 184: Statement “core eudicots that occurred 99 million years ago” needs a reference.

Reply: Yes, we have added a reference here.

Comments on the Quality of English Language

English may be improved.

Reply: We have obtained help from Nature editing service.

Author Response File: Author Response.pdf

Reviewer 2 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

I can confirm that the manuscript has been substantially improved and my suggestions have been included. I have no further comments on this manuscript.

Author Response

Comments and Suggestions for Authors

I can confirm that the manuscript has been substantially improved and my suggestions have been included. I have no further comments on this manuscript.

Reply: Thanks for your help and support

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

Dear authors,

This is an exciting paper. The results are presented, and the materials and methods have no serious flaws.

Please consider my comments.

General report#

The discovery of Antiquigemina pilosa is a notable contribution to science, this fossil provides new insights into the early diversification of core eudicotsc which is potentially very important.

The manuscript is innovative but require some revisions if possible, such as “phylogenetic analysis based on morphological data including Antiquigemina and a carefully selected set of extant and fossil core eudicot taxa (and relevant outgroups).

Also, it would strengthen the abstract to mention one more definitive synapomorphy that firmly places this fossil within the core eudicots.

Lines 12-13: The term "more than 3 sepals" and "more than 4 stamens" is slightly vague. Can the authors provide a more definite count or range (e.g., "4-5 sepals" or "at least 4 stamens").

Line 63: ‘ calyx caducous’ Are you sure about this character? if yes, how did you checked it?.

Line 72: “flower A and flower B” add parentheses “flower (A) and flower (B)”. and check this issue across the MS.

Line 160: replace ‘by 2) or 3)’ with " in the second or third possibilities ”

Line 171: replace ‘and not withering’ with “do not wither”

Line 193: add the authority in the first mention of the scientific name "Xerophyta humilis (Baker) T.Durand & Schinz"

Line 206: remove "different" as it is unnecessary here

Line 220: replace ‘different’ with “are different”

Lines 305: the scientific name should be written italic “Sabia”.

Comments for author File: Comments.pdf

Author Response

Comments and Suggestions for Authors

Dear authors,

This is an exciting paper. The results are presented, and the materials and methods have no serious flaws.

Reply: Thanks for your help and suggestions.

Please consider my comments.

General report#

The discovery of Antiquigemina pilosa is a notable contribution to science, this fossil provides new insights into the early diversification of core eudicotsc which is potentially very important.

Reply: Thanks for your pointing out this. It would be great if this could be done this time. We also plan to do it in the future. However, currently we just started collecting related data, and thus we are afraid that, at this time, it is premature to rush any conclusion basing one sparse data matrix. Also, apparently, this work cannot done in this manuscript with limited space.

Also, it would strengthen the abstract to mention one more definitive synapomorphy that firmly places this fossil within the core eudicots.

Reply: Thanks. We have done according to this instruction.

Lines 12-13: The term "more than 3 sepals" and "more than 4 stamens" is slightly vague. Can the authors provide a more definite count or range (e.g., "4-5 sepals" or "at least 4 stamens").

Reply: Thanks. We have done so.

Line 63: ‘ calyx caducous’ Are you sure about this character? if yes, how did you checked it?.

Reply: We compared the numbers of sepals in these two physically connected flowers. We found although the petals are still attached, the numbers of sepals in these flowers are different, implying that some of the sepals have fallen off in one of the flowers while the petals are intact. This is why we used the word “caducous”.

Line 72: “flower A and flower B” add parentheses “flower (A) and flower (B)”. and check this issue across the MS.

Reply: Thanks for pointing out this. We have corrected throughout.

Line 160: replace ‘by 2) or 3)’ with " in the second or third possibilities ”.

Reply: Thanks. We have done so.

Line 171: replace ‘and not withering’ with “do not wither”

Reply: Thanks. We have done so.

Line 193: add the authority in the first mention of the scientific name "Xerophyta humilis (Baker) T.Durand & Schinz"

Reply: Thanks. We have done so, although we delete the “T.”.

Line 206: remove "different" as it is unnecessary here.

Reply: Thanks. We have done so.

Line 220: replace ‘different’ with “are different”

Reply: Thanks. We have done so.

Lines 305: the scientific name should be written italic “Sabia”.

Reply: Thanks. We have done so.

peer-review-51358248.v1.pdf We appreciate your kindly and detailed suggestions and corrections.

Submission Date

21 September 2025

Date of this review

26 Oct 2025 14:22:03

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

The authors have not done much in the manuscript. They seem to resign to find relevant literature as Knobloch and Mai (1986). I do not consider their revision as sufficient.

Comments on the Quality of English Language

English may be improved.

Author Response

We have managed to secure the reference missing in the previous version. Now we have added the related information in the newer version. We also obtained professional editing service from Nature Group. Hope you are satisfied now.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

An interesting piece of research describing core eudicot flowers from the Mid-Cretaceous. The specimens are well-illustrated and the methods and results justify the conclusions, although the introduction is very short and could be expanded further. Nevertheless, there are significant issues with the language and style of the description etc. that need addressing.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The English is not acceptable for publication and reads in places like it has been auto-translated. There are multiples problems with tense, plurality and missing articles etc. and I have annotated some of these corrections (as far as line 89), but rewriting the ms is not the job of a reviewer. The description is written in conversational English and is too wordy - it needs considerable tightening of the text. The authors will need to engage with a proficient and/or native English speaker with experience in taxonomic writing before submitting a revised version

Author Response

Thanks for your comments for our manuscript. We have expanded the introduction. We have asked Springer Nature to make an official polish to improve the language quality. We have changed the language style in description part into concise taxonomical language.

Comments on the Quality of English Language

We are very sorry for making so many mistakes. All the mistakes are revised according to the peer-review file. We also checked the unrevised parts and made corresponding modifications.

Reviewer 2 Report

Comments and Suggestions for Authors

I have reviewed the manuscrit presented by Li et al. on a new taxon of paired flowers. The manuscript is well written, the fossils are well described and illustrated. Honestly, I have no major criticisms of the manuscript, because although I am a paleobotanist, I am not a specialist in fossil angiosperms. My suggestions for improvement and edits of the text are minor (see attached pdf).
Specific comments are:

Please include a geological/geographical map of the locality.
Do you have only one flower specimen (PB206703), or are there paratypes?
Is this new flower associated with vegetative structures (i.e., leaves)?

Comments for author File: Comments.pdf

Author Response

It is a pleasure to receive your positive comments for our manuscript. We have revised the manuscript accordance to the revision in PDF and have responded to your specific comments.

Specific comments are:

Please include a geological/geographical map of the locality.

We have added a Geographical sketch map of the amber locality in the Hukawng Valley.

Do you have only one flower specimen (PB206703), or are there paratypes?

We have only one specimen for the paired flowers of Antiquigemina pilosa. These flowers differ from all the other published records within Myanmar Amber. More specimens of Antiquigemina pilosa require further excavation in this locality.

Is this new flower associated with vegetative structures (i.e., leaves)?

These flowers only connect with a pair of bracts. Only impurities co-preserved within the amber. No information of vegetative structures of Antiquigemina pilosa have been found.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

This paper reports a highly significant and potentially significant discovery: two physically connected core eudicot flowers from mid-Cretaceous Myanmar amber. The highly documented morphological account of Antiquigemina pilosa gen. et sp. nov. is an important contribution to understanding the early diversification of core eudicots. The use of both stereomicroscopy and Micro-CT is to be welcomed and required for such delicate fossil material.

While the findings are interesting, the current manuscript requires substantial rewriting to reach the pinnacle of scientific rigor and readability. My prime issues are with comparative analysis at a suitable level, the robustness of certain interpretations, and the cohesion of narrative stream. With thoughtful resolution of these issues, this can be a true standout work.

Key Comments:

Nomenclature and Position of Taxon:

"Family Incertae sedis": Even if the deduction that A. pilosa doesn't fit comfortably into any modern family is understandable given its old age and strange combination of characters, the case needs to be well articulated as to why it's relegated to "incertae sedis" and not a new order or family. What are the morphological gaps or contradictions that hinder assignment to a living higher taxon? This needs to be more strongly argued.

Generic vs. Specific Diagnosis: The current genus and species diagnoses are slightly redundant. The generic diagnosis states "Flowers in pairs, each subtended by a bract" and "Flowers bisexual." The specific diagnosis adds, "In addition to that of the genus, pedicles and bracts are trichome-coated." This can be made more concise. Consider what actually separates Antiquigemina from other potential genera if others were found. Then again, the paired flower arrangement may be general, with the trichomes being specific. Explain these hierarchical differences.

Comparative Analysis (Table 1 and Discussion):

Lack of Depth of Comparison:
Table 1 is a good starting point, but the "Detailed comparison between A. pilosa with these families can be viewed in Table 1" under discussion is an overstatement. Only character states are listed in the table; the description following the table needs to adopt a harsher, point-by-point comparison of each character highlighting similarities and more importantly differences warranting its unique position. For example, why does anther attachment nature or disk presence/absence constitute such a crucial factor for differentiation of A. pilosa from, say, Saxifragaceae?

Focus on Apomorphies/Plesiomorphies: The account must move away from anecdotal contrast of characters and consider what characters are derived (apomorphic) and what characters are ancestral (plesiomorphic) in the basic eudicots. This would make the argument more robust for

A. pilosa being a "transitional form". What set of characters is it precisely that renders it transitional?

Wider Context for "Rare Specialization": The sentence "Overall, such specialization is relatively rare among core eudicots, and should be informative on the affinities of A. pilosa" is too imprecise. What specialization are you referring to (e.g., tricarpellate ovary with pentamerous perianth and half-inferior ovary)? This has to be made explicit and its relative rarity supported quantitatively if possible, or at least justified with examples of occasional occurrence.

Interpretation of Developmental Stages (Section 4.1):

Stricter Argument for Developmental Sequence: The argument of Flower A as being more developed than Flower B based on style bifurcation and lack of calyx is valid but can be made stronger. While
Litchi chinensis is cited, is there broader evidence of progressive style bifurcation as a general sign of maturation in core eudicots?

Calyx Caducity: The taphonomic hypothesis that the calyx in Flower A "may have dropped off completely" by caducity is a reasonable one, but since it is of primary significance in identifying the growth stages, think of other taphonomic hypotheses for the same (e.g., preservation damage, pre-fossilization rot). Think of these alternatives, although discarded.

Inflorescence Interpretation: The botryoid/cyme vs. paired-flower cyme debate is well argued, and then the authors decide that "more evidence is necessary to demonstrate whether these specializations had arisen during the initial diversification of core eudicots". This is a valid observation. Does any aspect of A. pilosa itself, other than the paired aspect, predispose to one inflorescence over another? Even in a speculative vein, it's worth thinking about in terms of current morphology.

Clarity regarding "Lobed Petal" Interpretation:

Discussion of the lobed petal is confusing to some extent. While the authors prefer the lobes of a single petal, this can influence the "pentamerous or hexamerous" perianth character. Ensure the implications of this ambiguity are always taken care of across the manuscript, particularly in the diagnosis and comparative tables. Perhaps a specific

A reason for such splitting, or a reference to previously recognized taxa with similar petal morphologies, would be welcome.

Figures and Visual Communication:

Figure 1J (Flower Diagram): This figure is critical in judging the floral morphology. The "stamens with solid line are seen at least in one technique (Stereomicroscope or Micro-CT)" and "Stamens with broken line are only preserved as filament residues" is perfect clarity. However, make sure the

Its direction (e.g., anterior/posterior) is regular and clearly marked, especially when defining such characters as antipetalous stamens.

Micro-CT Limitations: The "Remarks" section identifies the limitations of Micro-CT (e.g., limited density contrast). Good scientific practice. Maybe continue to describe how these limitations influenced specific character interpretations (e.g., "at least 4 stamens").

Minor Comments

Abstract Clarity: The abstract is clear, but "The paired flowers differ in diverging style and calyx, suggesting different developmental stages of the flowers" could be slightly better with smoother flow, possibly "The differences in style divergence and calyx presence between paired flowers indicate different developmental stages."

Keywords: Include "fossil flower" or "palaeobotany" in the keywords to enable it to be more easily found by researchers outside the subject area of micro-morphology.

Introduction Flow: The introduction very effectively sets up the relevance of early core eudicot fossils.

Units Consistency: Try not to inconsistently switch between using μm vs. micrometers in the text, but it seems fine for now.

"Caducous Calyx": While mentioned, maybe it would be a good point to briefly define the term "caducous calyx" first, perhaps in the specific diagnosis since it is a useful feature.

Sentence Structure: Some sentences can be clarified with minor reformulation for concision and impact (e.g., "These flowers gave a raw material recording the early diversification of core eudicots" could be "These flowers provide direct evidence for early diversification of core eudicots.").

Figure Citations: Ensure that all figures and subfigures mentioned in the text are properly and clearly cited. For instance, in "A pair of flowers were found preserved within a piece of brownish amber (Figure 1A-J)", it is fine, but ensure subsequent ones such as "(Figure 1K)" are also mentioned.

Hyphenation: Ensure proper and consistent hyphenation (e.g., "mid-Cretaceous" vs. "Mid-Cretaceous"). The title has "Mid-Creta-ceous" which is a line break fault and should be "Mid-Cretaceous."

Author Response

Dear Authors,

Thanks for your comments on the significance of our work. We appreciate your detailed and inspiring comments. The corresponding response is written beneath each comment.

Key Comments:

Nomenclature and Position of Taxon:

We agree with the reviewer. However, the unique and weird features of the flowers prevent us from placing them in any known families. If the reviewer has a hintful suggestion, we will consider it seriously.

We use the combination of features of flower parts as the generic diagnosis of Antiquigemina since it differs from any other flower genus in our perception. Types of hairs and trichomes are often used to distinguish species within the same genus for extent plant taxonomy. Thus we treat them as specific diagnosis. We moved “Calyx caducous” from generic diagnosis to specific diagnosis as your following suggestion.

Comparative Analysis (Table 1 and Discussion):

Our distinction of Antiquigemina pilosa and families with inferior or sub-inferior tricarpellate ovary is based on both key character and character assemblages. We have add detailed discussion in this section. Saxifragaceae can be distinguish from A. pilosa for having lobed ovary.

Many characters of Antiquigemina pilosa cannot determined as apomorphies or plesiomorphies, even probably caused by preserving conditions. For example, the tricarpellate ovary of A. pilosa can be a plesiomorphy of eudicots, or an apomorphy derived in some clade of core eudicots. Due to the limited number of fossil specimen, we can only present all the possibilities in the discussion.

pilosa being a "transitional form". What set of characters is it precisely that renders it transitional?

Flowers with pentamerous perianths and a tricarpellate ovary in some basal eudicots have been explained as a transitional form toward the typical pentamerous flower in core eudicots according to flower development. As one possibility, we suggest that A. pilosa might be an early form of core eudicots since it well-differentiated sepals and petals, but without a typical pentamerous flower. The atypical character combination of A. pilosa reveals an transitional, un-stable, uncanalized status of eudicot flower evolution in their early evolution

We are sorry for causing the confusion here. We mean the tricarpellate ovary is relative rare as a derived feature in core eudicots. We have changed the expression in this paragraph as “The tricarpellate ovary has also evolved independently within several different orders of core eudicots [26]. The relatively limited space for gynoecium development compared with the outer whorls probably leads to a reduction in carpel numbers [27]. Derived from the specialization of pentamerous flowers may serve as an alternative hypothesis for the tricarpellate ovary of A. pilosa.”

Interpretation of Developmental Stages (Section 4.1):

Stricter Argument for Developmental Sequence: The argument of Flower A as being more developed than Flower B based on style bifurcation and lack of calyx is valid but can be made stronger. While Litchi chinensis is cited, is there broader evidence of progressive style bifurcation as a general sign of maturation in core eudicots?

The distal portion of pistil gradually dehiscing during the maturation of flower can be observed in some angiosperms. However, the lobed part only limit in the stigma or the stigma and the tip of the style in many of them (e.g. Campanula), not as deep into the middle part of the style as A. pilosa. Therefore, we only present the most apropos example of Litchi chinensis in the manuscript.

We found no scar or residues on the outer side of the hypanthium in micro-CT. Therefore, the possibility that preservation damage or pre-fossilization damage induced the absence of calyx is relatively small.

The connected paired flower and the paired bracts of A. pilosa are quite similar to part of a paired-flower cyme. However, previous theories of paired flowers forming involves relatively complicated specialization. The early age of A. pilosa make us hesitant whether angiosperm have developed such complicated inflorescences within a relatively short time. Thus, we present two possibilities simultaneously in the article.

Clarity regarding "Lobed Petal" Interpretation:

A reason for such splitting, or a reference to previously recognized taxa with similar petal morphologies, would be welcome.

Lobed petals in Antiquigemina pilosa may reflected the earliest corolla may have high developmental plasticity, as the original form of petals——leaves, sometimes possess the plasticity of lobation (e.g. Ginkgo biloba). On the other hand, lobed petals may result from accidentally external damage. Based on current evidence, whether the existence of lobed petals and their position is stable or not cannot be determined, making it impossible to tell whether the “lobed petal” are exactly two stable petals, developmental mutants, or just an accident. We present all the interpretations in line 173–179, but avoid to make a conclusion.

Figures and Visual Communication:

Thanks. We have modfied according to this sugestion.

Its direction (e.g., anterior/posterior) is regular and clearly marked, especially when defining such characters as antipetalous stamens.

We add arrows pointing out the antipetalous stamens in the figures.

We appreciate your comments on our interpretation on micro-CT limitation. We use “at least” to emphasize “the spacing between sepals or stamens is uneven”. But we cannot judge whether it is original or artefacts.

–Minor Comments

Done. We have also made adjustments to the language of other parts of the abstract.

Keywords: Include "fossil flower" or "palaeobotany" in the keywords to enable it to be more easily found by researchers outside the subject area of micro-morphology.

We add “fossil flower” in the keywords.

Introduction Flow: The introduction very effectively sets up the relevance of early core eudicot fossils.

Units Consistency: Try not to inconsistently switch between using μm vs. micrometers in the text, but it seems fine for now.

We use μm in stead of mm when the length is less than 1 mm.

"Caducous Calyx": While mentioned, maybe it would be a good point to briefly define the term "caducous calyx" first, perhaps in the specific diagnosis since it is a useful feature.

We added “Sepals in a caducous calyx fall off earlier than other flower parts, and not withering when fallen.” in line 196. We moved “calyx caducous” from generic to specific diagnosis.

Done. We have asked Springer Nature to make an official polish to improve the language quality.

Done.

Hyphenation: Ensure proper and consistent hyphenation (e.g., "mid-Cretaceous" vs. "Mid-Cretaceous"). The title has "Mid-Creta-ceous" which is a line break fault and should be "Mid-Cretaceous."

Done. The latter is a problem in word wrapping.

Reviewer 4 Report

Comments and Suggestions for Authors

Li et al. describe a pair of attached flowers preserved in amber from the mid-Cretaceous of Myanmar. The flowers are apparently pentamerous with tricarpellate ovaries, and the authors hypothesize the plant belongs to the core-eudicot clade. The authors spend some time discussing alternative interpretations of the morphology necessitated by the challenges of observing minute three dimensional structures within amber, and they use micro-CT scanning to reveal additional characters, even though subtle differences in density obscure some features. In my assessment, this discovery is worthy of publication, but it would benefit from some revision and proofreading. I have included some suggestions for proofreading only to be helpful. This is a minor point, but I caution against “twin flower” in the title because twinflower is the common name of the genus Linnea borealis (Caprifoliaceae).

Introduction:

What do we already know about the diversity of flowers from the Myanmar Amber Biota? There are more than thirty flowers that have been described, and some of the others also have combinations of characters suggesting a relationship to eudicots.

Line 22 Change “took” to “comprise”

Line 27: “The details of this radiation remain elusive because of the limited fossil record of early core eudicots”. The phrase “due to” means caused by, and the authors write “relatively limited,” but it is not clear relative to what, so I recommend just omit the word relative, or explain it.

Results:

It is not clear that the generic diagnosis is sufficiently detailed to distinguish it from other genera. The job of a generic diagnosis is to state the combination of characters that serves to distinguish the new genus from other genera in the same higher taxon, but there are other eudicot plants with a bracteate inflorescence and flowers with a distinct calyx and corolla, filamentous stamens with bilocular anthers, a tricarpellate half inferior ovary, and a bifurcate style.

How do you know the filaments you call “staminodes” are not stamens with the anthers broken off prior to preservation?

The images in figures 1 and 2, especially the whole flowers, are quite small, so the greyscale makes it difficult to see the structures that the authors are referring to.

Line 92: how long are the branches?

Line 111: This sentence is confusing. Also, the figures are not large enough for the reader to judge whether these are indeed lobes, a tear, or some other included material. A digital slice at another angle might show this better.

Discussion:

It seems like this manuscript is missing a conclusion paragraph. It just ends abruptly with the decision to leave the genus orphaned within the eudicots (which I think is reasonable). The manuscript could finish with something like: “The description of Antiquigemina pilosa increases our knowledge of the diversity of the mid-Cretaceous Myanmar Amber Biota and is the thirty-third (or whatever) species to be described based on fossil flowers from the Myanmar Amber (citations…). This plant displays morphology characteristic of core eudicots, but the systematic relationships of A. pilosa to other angiosperms remain unclear. Nonetheless, it strengthens the inference that the diversification of core-eudicots was underway…

Comments on the Quality of English Language

Line 52 “tricarpellate”

Line 57: involute inward is redundant

Line 92: The organization of the stigmatic surface is not clear. I recommend describing how the style of flower A is bifurcated distally and the branches form an angle of 30 degrees.

Line 96: the ovary is tricarpellate

Line 102: differential

Line 103: “The description is based on observations using both methods.”

Line 104: are these measurements for the whole whorl or the individual organs in the whorls?

Line 106: perianth parts

Line 108: Do you mean “the spacing between the organs in each whorl is uneven”?

Line 159: I think categorizing would be a better word than defining.

Line 162: who are “these”?

Line 166: …forming such inflorescences involves complex [developmental?] specializations…

Line 168: botryoid inflorescence (missing the word inflorescence; -oid means “like”).

Author Response

We appreciate your detailed and inspiring comments. The corresponding response is written beneath each comment. We change the title as “Paired Flower of Core Eudicots Discovered from Mid-Cretaceous Myanmar Amber” and avoid using “twin flower” to stand for Antiquigemina pilosa in the whole manuscript.

Introduction:

We have add the related information the in introduction.

Line 22 Change “took” to “comprise”

Done.

We revise this sentence as “However, owing to the relatively limited fossil records of early core eudicots, the details of this radiation remain elusive”.

Results:

We appreciate your kindness pointing out this. We have tried our best to compare Antiquigemina with extant plant genera, and thus far, we have not found an identical match (this is the situation we currently face, as otherwise we would have classified it within an extant genus). Please inform us which genus has such a feature combination. We would consider your suggestion seriously.

How do you know the filaments you call “staminodes” are not stamens with the anthers broken off prior to preservation?

Your consideration is necessary. We apologize for ignoring this possibility. We decided to use “stamens” for all the filament with or without anther, and add a paragraph in remarks part present the possibility of staminodes and broken off.

The images in figures 1 and 2, especially the whole flowers, are quite small, so the greyscale makes it difficult to see the structures that the authors are referring to.

We enlarge the size of Figures 2E–F, 2H–I, 3D–E. We add a blue dotted line in Figure 2H to show the outline of the sepals.

Line 92: how long are the branches?

The branches are 1.0–1.3 mm. We add this information in line 180.

We have enlarge the figures and added serial numbers for perianths to make this part clear.

Discussion:

It seems like this manuscript is missing a conclusion paragraph. It just ends abruptly with the decision to leave the genus orphaned within the eudicots (which I think is reasonable). The manuscript could finish with something like: “The description of Antiquigemina pilosa increases our knowledge of the diversity of the mid-Cretaceous Myanmar Amber Biota and is the thirty-third (or whatever) species to be described based on fossil flowers from the Myanmar Amber (citations…). This plant displays morphology characteristic of core eudicots, but the systematic relationships of A. pilosa to other angiosperms remain unclear. Nonetheless, it strengthens the inference that the diversification of core-eudicots was underway…

Thanks. We have added a conclusion part emphasize the significance of A. pilosa.

Comments on the Quality of English Language

Line 52 “tricarpellate”

Done.

Line 57: “involute inward” is redundant

Done.

Line 92: The organization of the stigmatic surface is not clear. I recommend describing how the style of flower A is bifurcated distally and the branches form an angle of 30 degrees.

The boundary between the stigma and the style of A. pilosa is not clear. In the revised manuscript, we uniformly use the expressions as “bifurcation of the style” and “bifurcated style”.

Line 96: the ovary is tricarpellate

Done.

Line 102: differential

Done.

Line 103: “The description is based on observations using both methods.”

We simplified the sentence as “The characteristics based on observations using both methods are more reliable.”

Line 104: are these measurements for the whole whorl or the individual organs in the whorls?

These data are based on the each organs of the whole whorl. We changed “their sizes are distinct form each other” into “the sizes of sepals are distinct from those of petals”.

Line 106: perianth parts

Done.

Line 108: Do you mean “the spacing between the organs in each whorl is uneven”?

Yes. We changed the expression “calyx and androecia left gaps in the whorl” into “the spacing between sepals or anthers is uneven”.

Line 159: I think categorizing would be a better word than defining.

We change “defining” into “categorizing” here.

Line 162: who are “these”?

Sorry for making the confusion. We changed “these flowers” into “A. pilosa”.

Line 166: …forming such inflorescences involves complex [developmental?] specializations…

These specializations have both developmental and evolutionary implications. Considering Antiquigemina pilosa is a relatively early example of eudicots, we doubt whether there is enough time for eudicots to evolve such specializations.

Line 168: botryoid inflorescence (missing the word inflorescence; -oid means “like”).

Done.