The fabricated pterosaur Bakiribu

[Hebert Bruno Campos]

Hi there,

Here few observations on the supposed ctenochasmatid pterosaur Bakiribu waridza from the Romualdo Formation of Brazil:

Several points weaken the interpretation of the specimen as a dinosaur regurgitalite. First, the attribution depends on an unusually specific behavioral scenario — ingestion and subsequent regurgitation by a dinosaur — without direct evidence identifying the producer, such as associated gastric contents, bite traces, digestive corrosion, or a clear taphonomic context linking the mass to a dinosaur carcass or track-bearing horizon. 

Second, the Romualdo Formation is exceptionally rich in fish remains, and isolated or concentrated fish elements are common in this depositional setting; therefore, a fish-based explanation is taphonomically more parsimonious than invoking a rare dinosaur-mediated event. 

Third, the anatomical interpretation of the material as pterosaurian appears vulnerable if the preserved elements can be more simply explained as fish bones, scales, or cranial fragments, especially because fragmentary fish material may mimic thin, elongate pterosaur bones when compressed or displaced. 

Fourth, a true regurgitalite would normally be expected to show a coherent set of features consistent with partial digestion and expulsion, such as clustering, acid etching, breakage patterns, and selective preservation of resistant elements; if these features are absent, weakly developed, or not rigorously distinguished from ordinary disarticulation and concentration, the hypothesis becomes speculative. 

Finally, assigning both the prey identity and the predator identity in the absence of independent evidence risks overinterpreting a complex fossil association, turning a possible taphonomic accumulation into a behavioral narrative that is more dramatic than demonstrable.

References: 

Kellner, A.W.A. Scientific errors in paleontology — the case of Bakiribu: pterosaur or fish? Anais da Academia Brasileira de Ciências 98 (2026). https://doi.org/10.1590/0001-3765202620269802

Pêgas, R.V., Aureliano, T., Holgado, B. et al. A regurgitalite reveals a new filter-feeding pterosaur from the Santana Group. Sci Rep 15, 37336 (2025). https://doi.org/10.1038/s41598-025-22983-3

Unwin, D.M., Smith, R.E., Cooper, S.L.A. & Martill, D.M. Reinterpretation of Bakiribu waridza from the Romualdo Formation (Lower Cretaceous) of Brazil: a fish not a pterosaur. Anais da Academia Brasileira de Ciências 98 (2026). https://doi.org/10.1590/0001-3765202620251374

Regards,

Hebert

[Mickey Mortimer]

The most disturbing parts of the situation are stated by Kellner (2026)-

"After the manuscript came back from the review process with positive evaluations (the reviewers were researchers working with pterosaurs and fishes), the lead authors of Pêgas et al. (2025) were invited to respond. Although they initially agreed, when I contacted them about their missed deadline, pointing out that the AABC would publish Unwin and colleagues’ results with or without their response and would settle the matter (at least for the AABC), they did not ask for an extension (which, if reasonable, would be considered) and declined our offer. As informed, they are working on some analyses that, according to them, will conclusively “prove” the specimen to be a pterosaur (A.M. Ghilardi, pers. comm. 2026, R. Pêgas, pers. comm. 2026)."

"When it became clear that Pêgas and colleagues would not respond to Unwin et al. (2026), I asked to examine the material for the present editorial. To make a long story short, although initially there was an indication that I would get permission to see the holotype (a category of specimens that, due to their importance, should be readily made available to scientists), after making it clear that I disagreed with their interpretation, several difficulties arose, and it became evident that I would not be able to examine the holotype of Bakiribu waridza within the timeframe necessary to complete this editorial."

Mickey Mortimer

[Hebert Bruno Campos]

Hi Mickey,

Thank you for pointing this out. I agree that these passages from Kellner (2026) identify some of the most troubling aspects of the situation.

For me, the central issue is no longer only whether Bakiribu waridza is a pterosaur or a fish, although that anatomical question is obviously fundamental. The broader concern is how the scientific process is being handled after publication. If a major reinterpretation challenges the taxonomic identity of the holotype, then the most appropriate response would be open, detailed, and timely scientific engagement — ideally including direct examination of the specimen, comparative anatomical evidence, and a formal response to the critique.

The fact that the authors apparently declined the opportunity to respond in the same venue is problematic, especially if they claim to be preparing analyses that will “conclusively prove” the specimen to be a pterosaur. Extraordinary claims require transparent evidence, not future promises. Until such evidence is published, the original interpretation remains vulnerable, particularly because the alternative identification as fish material appears anatomically and taphonomically plausible.

Even more concerning is the reported difficulty in accessing the holotype. A holotype is not merely a symbolic object; it is the name-bearing specimen on which the validity and interpretation of the taxon depend. Because of that, it should be accessible for qualified scientific examination, especially when its identity is under serious dispute. Restricting or delaying access after disagreement with the original interpretation creates the impression that the hypothesis is being protected from scrutiny rather than tested through normal scientific procedure.

This is precisely why the case goes beyond a simple taxonomic disagreement. It raises questions about reproducibility, transparency, peer review, curatorial responsibility, and the public communication of paleontological claims. Peer review does not end scientific debate; it begins a broader process of evaluation. If post-publication criticism identifies serious anatomical problems, the response should be evidence, access, and open discussion — not silence, postponement, or barriers to examination.

In my view, the Bakiribu case illustrates the risks of what we might call “fast paleontology”: an extraordinary claim receives rapid publication and public amplification, but the subsequent scrutiny reveals that the anatomical foundation may not be sufficiently robust. If the specimen is indeed fish material rather than pterosaurian, then the damage is not only taxonomic. 

Best regards,

Hebert

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[Ilya Sadykov]

It amazes me that the practice of hiding specimens from other authors and trying to shield them from any sound re-evaluation still exists in the paleontological community. A prime example for me is Robert DePalma, who hasn't allowed anyone to access the original Dakotaraptor specimen following a series of critical remarks from authors like Andrea Cau.

четверг, 7 мая 2026 г. в 18:58:06 UTC+5, Hebert Bruno Campos:

[Russell Engelman]

It seemingly gets worse. Pêgas et al. put out a statement in a Brazilian newspaper.

https://www1-folha-uol-com-br.translate.goog/ciencia/2026/04/cientistas-ingleses-contestam-a-descoberta-de-pterossauro-filtrador-brasileiro-achado-em-vomito-fossil.shtml?pwgt=kqsyb30ecrzz5smfmyvheso6nifr4bilekat1zbglr9xte6a&utm_source=whatsapp&utm_medium=social&utm_campaign=compwagift&_x_tr_sl=pt&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=wapp

Some of the statements in it are a little weird, including...

"Pêgas, however, refutes the criticisms presented in the preprint and says that the British made "crude interpretations and lied in part of the description" and that she and her colleagues are preparing new analyses that corroborate that it is a pterosaur."

and...

"The Brazilian authors state that disagreements and differing opinions are part of the scientific process, and these are welcome when accompanied by dialogue. "The contact was imposed, not conversational, so to speak," says Pēgas."

Pêgas et al. claim they invited critics to see the fossils, but Martill and Kellner dispute this. It reminds me of what I've heard about the situation with DePalma, where some people have claimed DePalma has invited critics to see the specimens and they've had no problems getting access, whereas others have said they've actually tried taking DePalma up on his offer and got ghosted. In both cases I have no idea who is telling the truth.

[Hebert Bruno Campos]

Dear Mickey,

Another aspect that deserves attention is the rather curious repository arrangement of the Bakiribu material:

As far as I understand, part of the specimen was retained in the collection of one of the authors’ own institutions, while the counterpart was donated to the Museu de Paleontologia Plácido Cidade Nuvens, in Santana do Cariri, Ceará, Brazil. I do not want to overstate the point, but this arrangement is, at the very least, unusual enough to invite questions — especially because the specimen later became the basis for a new taxon, a major anatomical claim, and a highly publicized behavioral interpretation.

There is a certain irony here. A fossil presented as sufficiently important to establish a new pterosaur taxon and support an extraordinary paleobiological scenario was not, apparently, deposited as a fully unified reference specimen in a single, stable, broadly accessible public repository. Instead, the material was divided between an author-linked institutional collection and a regional museum collection. That may be administratively explainable, but scientifically it creates avoidable complications.

For a controversial holotype, especially one whose identity is now disputed, repository clarity is not a minor technical detail. It directly affects reproducibility, access, comparative study, and confidence in the published interpretation. If the part and counterpart preserve complementary anatomical information, then separating them across institutions can make reassessment more difficult. This becomes even more problematic when independent researchers report difficulties in examining the relevant material.

The irony, of course, is that a paper framed around an exceptional Brazilian fossil and promoted as a landmark discovery should ideally exemplify the highest standards of curatorial transparency. Instead, the case now seems to raise precisely the opposite questions: who controls access, where the decisive anatomy is preserved, whether both parts are equally available for study, and whether the repository arrangement facilitates or hinders independent verification.

In my view, this should not be treated as a personal issue, but as a matter of scientific procedure. A name-bearing specimen, particularly one involved in a significant post-publication dispute, should be curated in a way that maximizes accessibility, documentation, and independent scrutiny. Otherwise, the situation risks appearing less like open science and more like ownership management around a contested interpretation.

Regards,

Hebert

Em qui., 7 de mai. de 2026, 10:01, Mickey Mortimer <therizino...@gmail.com> escreveu:

[Dawid Mazurek]

Wholly agree, except one point: "significant post-publication dispute'' cannot be used as an argument, because it happens POST holotype being deposited.

Dawid