When pterosaur workers dismiss

Earlier we looked at a new PeerJ paper by Mark Witton (2015) on the possibility of inept terrestrial pterosaurs:

Witton MP 2015.Were early pterosaurs inept terrestrial locomotors? PeerJ 3:e1018<doi: https://dx.doi.org/10.7717/peerj.1018

Witton chose (as you’ll see below by this own admission) to ignore any data on bipedal pterosaurs by Peters and others. The ignored data makes pterosaurs as agile as living birds on land. I pointed that out to him through the appropriate forum, which is the whole point of PeerJ feedback. Here’s how it went back and forth. Check out the blue links wherever possible. And don’t forget to read to the concluding paragraph after the last list of references this time.

This was my first list of suggestions, along with a required headline:

Why was published literature by Peters ignored when it addresses so many of the issues raised and dismissed by the Witton manuscript?

Several papers and a website by Peters (see below) address several problems ignored by this manuscript/paper including:

  1. Basal pterosaur ichnites (they are known, have been published and none are quadrupedal, some are digitigrade)
  2. The origin of pterosaurs (among bipedal fenestrasaurs each with uropatagia, trailing each hind limb). Objections to this scenario by Hone and Benton (2007, 2008) were due to typos in their dataset and deletion of two fenestrasaurs and 75% of the data from a third along with deletion of all data from Peters 2000, an original candidate facing the alternate scenario, among many other problems).
  3. The presence or absence of compressed metatarsals on pterosaurs, (typical keys to digitgrady and plantigrady).
  4. The uropatagium problem. (So far observed only in one specimen, Sordes, which was shown to be an illusion caused by bone and membrane dislocation during taphonomy. All other pterosaurs and their predecessors have twin uropatagia).

Peters, D. 1995. Wing shape in pterosaurs. Nature 374, 315-316.
Peters, D. 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods. Ichnos, 7: 11-41
Peters, D. 2000b. A redescription of four prolacertiform genera and implications for pterosaur phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106: 293-336.
Peters, D. 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. Historical Biology 15: 277-301.
Peters, D. 2007. The origin and radiation of the Pterosauria. Flugsaurier. The Wellnhofer Pterosaur Meeting, Munich 27.
Peters, D. 2009. A Reinterpretation of Pteroid Articulation in Pterosaurs – Short Communication. Journal of Vertebrate Paleontology 29(4):1327–1330, December 2009
Peters, D. 2010. In defence of parallel interphalangeal lines. Historical Biology iFirst article, 2010, 1–6 DOI: 10.1080/08912961003663500
Peters, D. 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification. Ichnos 18(2):114-141.
Peters, D. 2010-2015. http://www.reptileevolution.com
Hone DWE and Benton MJ 2007. An evaluation of the phylogenetic relationships of the pterosaurs to the archosauromorph reptiles. Journal of Systematic Palaeontology 5:465–469.
Hone DWE and Benton MJ 2008. Contrasting supertree and total evidence methods: the origin of the pterosaurs. Zitteliana B28:35–60.

Response from the author (Mark P. Witton)
The assertion that the work of Peters has been ignored by this paper implies poor scholarship on my behalf, and that the works listed in Peters’ comment are as worthy of discussion as any other piece of pterosaur literature. It is true that Peters’ body of work did not inform my article, but my reasons for overlooking his papers will be familiar to those who follow pterosaur research.

My goal here is not to engage or argue with Peters. I – and my colleagues – have learned this is a largely futile exercise. Nor do I intend to write additional comments on this point or respond to his inevitable replies. However, for the benefit of naive parties reading these comments, some context may be useful. Because the substantial, fundamental problems with Peters’ research – the cause for myself and other workers ignoring his past contributions – are so well known to those studying fossil reptiles, I need only summarise them here. More detailed overviews of Peters’ work, the miseducation now synonymous with his name, and his attitude to other researchers, are provided by Bennett (2005) and Naish (2012) – links to these pieces are provided below.

The works of David Peters, including those related to subjects he mentions above (claims of non-pterodactyloid trackways, interpretation of pterosaur wing shapes, phylogenetic conclusions and limb function) are beyond controversial: they have been demonstrated as unreliable and untrustworthy by multiple authors (e.g. Unwin and Bakhurina 1995; Bennett 2005; Hone et al. 2009; Elgin et al. 2011). Infamously, at the core of all Peters’ work are tracings of photographs of fossil specimens, which he obtains using books, papers and online image searches. He claims to find specimen details in these photographs which no-one else has seen, including large portions of skeletons invisible to the naked eye; enormous, but invisible sheets of soft-tissue; and minute details – individual bones and fenestrae – in poorly-preserved, crushed regions of 2D fossils. These interpretations inform all his palaeobiological hypotheses, including his numerous alternative takes on extinct animal anatomy and functionality, as well as his entirely idiosyncratic concept of amniote phylogeny, which bears little resemblance to those based on standard molecular or morphological approaches.

Finding the structures Peters’ purports to uncover via his computer screen proves impossible when looking at actual specimens, even using detailed examination techniques such as CT scanning or microscopy (e.g. Unwin and Bakhurina 1995; Bennett 2005; Elgin et al. 2011). It is widely agreed by specialists that he is ascribing significance to artefacts of preservation and preparation, shadows in photographs, and other phenomena unrelated to actual specimen morphology (e.g. Unwin and Bakhurina 1995; Bennett 2005; Elgin et al. 2011; Naish 2012). Those workers who have conducted dedicated investigations of Peters’ methods provide wholly damning assessments of his ideas and techniques. On Peters’ ‘hinge-lines’ method of identifying track makers and foot function, Hone et al. (2009) “strongly advise against the use of hinge lines as a guide to functional analysis, a source of phylogenetic information, or a basis for identifying trackmakers in the ichnological record”. On digitally tracing photographs to find ‘missing’ fossil anatomies, Bennett (2005) has said “Peters’ method is flawed and his reconstructions are fantasy”. The same technique prompted Elgin et al. (2011) to describe his methods as “subjective and produc[ing] false and often fantastical images that have no value to science in general”. As early as 1995, Unwin and Bakhurina were calling his methods “unreliable”.

First-hand experience with many specimens Peters’ claims to have reinterpreted has led to my complete agreement with those denouncing his work in print: it is obvious that his papers and online articles are informed by pareidolia and personal opinion instead of an objective, scientific approach. I am aware of no practising researchers who argue differently.

Here and elsewhere, Peters argues his work is being ignored, and that workers like myself are taking ‘blinkered’ approaches to avoiding his controversial ideas. His persistent negative appraisals of virtually all findings in reptile palaeontology are now as well known as his tracing-based interpretations. Alas, one individual stating they are ‘right’ and that all other practising vertebrate palaeontologists are ‘wrong’ (as he regularly professes at his blog and website) does not make for controversy, nor does their insistence of scientific validity refute the considerable discussion showing their work as critically, fundamentally flawed (see Naish 2012 for the history, references and links surrounding Peters’ work). It seems the only individual bemoaning the lack of David Peters citations in contemporary pterosaur research is David Peters: others, including myself, see little to no benefit in the continued discussion of his unscientific, flawed approaches.

Bennett, S. C. 2005. Pterosaur science or pterosaur fantasy? Prehistoric Times, 70, 21-23. (direct link: http://bigcat.fhsu.edu/biology/cbennett/Bennett-PT-article.pdf)
Elgin, R. A., Hone, D. W., & Frey, E. (2011). The extent of the pterosaur flight membrane. Acta Palaeontologica Polonica, 56, 99-111.
Hone, D. W., Sullivan, C., & Bennett, S. C. (2009). Interpreting the autopodia of tetrapods: interphalangeal lines hinge on too many assumptions. Historical Biology, 21, 67-77.
Naish, D. 2012. Why the world has to ignore ReptileEvolution.com. Tetrapod Zoology (direct link: http://blogs.scientificamerican.com/tetrapod-zoology/2012/07/03/world-must-ignore-reptileevolution-com/)
Unwin, D.M. and Bakhurina, N.N. 1995. Wing shape in pterosaurs. Nature 374, 316.

My response:
It is odd and unprofessional to attack the writer of a helpful comment (and his methods) while continuing to ignore the specimens of pes only tracks in the literature (see below).

With regard to Witton’s references, Bennett 2005 (writing in a fanzine) was correct in his assessment of earlier mistakes by Peters (also writing in a fanzine). None of this is in the academic literature.

On the same note, but elevated to the academic literature, Bennett (2007) made numerous observational errors (mistaking a maxilla for a sclerotic ring and ignoring the actual sclerotic rings, to name but a few). So mistakes happen. Corrections are made. This is the process of Science.

Evidently Witton does not forgive fanzine notions, but instead ascribes all future output as tainted. If so, then all of his example authors are likewise tainted:

Elgin, Hone and Frey (2011) made several mistakes in observations using crude cartoonish drawings to poorly trace subtle wing membranes, missing many details.

Hone, Sullivan and Bennett (2009) intended to disprove the universal hypothesis of parallel interphalangeal hinge lines, but avoided using all of the best examples (tetrapods with four and five digits). Even so they several times admitted to recovering hinge lines, even on three-toed taxa in which the digits were fully flexed and therefore not in their ‘useful’ positions.

In a blogpost Naish (2012) used artwork from paleoartists other than Peters to demean discarded hypotheses and observations, again (as above), not originating in the academic literature.

Unwin and Bakhurina (1995) failed to show the displacement of the left radius and ulna of their holotype Sordes specimen, which displaced the associated wing membrane and has since been misinterpreted as a leg-spanning uropatagium. No other pterosaur has documented a similar morphology. That is because this hypothesis is based on a misinterpretation/illusion.

Witton himself has employed imagination in his reproductions of an embryo pterosaur (Pterodaustro) with a large orbit and small rostrum when the data shows that all pterosaur embryos, juveniles and subadults had adult proportions, and in this regard are different than many other tetrapods. I could list many other observational errors.

It is important to show mistakes without rancor. It is also important not to dismiss all future output of a worker based on a few misinterpretations early in a career published in a fanzine. I certainly do not intend to brand any of the above workers the way Witton has branded Peters, but reserve the right to be critical, only if necessary, of any future output.

Bottom line, because there are several examples of bipedal pterosaur ichnites in the academic literature it is incumbent upon the author to address these examples and not ignore them. This is the academic forum for Witton to address his issues with all bipedal pterosaur tracks in the literature. It is also incumbent upon the author to treat peer-reviewed literature with more attention than he treats fanzines or blogposts that were not peer-reviewed.

Bennett SC 2007. A second specimen of the pterosaur Anurognathus ammoni. Paläontologische Zeitschrift 81(4):376-398.
Conrad K, Lockley MG and Prince NK 1987. Triassic and Jurassic vertebrate-dominated trace fossil assemblages of the Cimarron Valley Region: Implications for paleoecology and biostratigraphy. New Mexico Geological Society Guidebook. 38th Field Conference, Northeastern New Mexico 1987. 127-138.
Lee YN, Azuma Y, Lee H-J, Shibata M, Lu J 2009. The first pterosaur trackways from Japan. Cretaceous Research 31, 263–267.
Kim JY, Lockley MG, Kim KS, Seo SJ and Lim JD 2012. Enigmatic Giant Pterosaur Tracks and Associated Ichnofauna from the Cretaceous of Korea: Implication for the Bipedal Locomotion of Pterosaurs. Ichnos 19 (1-2): 50-65.DOI:10.1080/10420940.2011.625779

I’ll add here in conclusion
the current crop of pterosaur workers continues to wonder where pterosaurs originated, even though that was established 15 years ago. They continue to hold the purported uropatagium of Sordes as their paradigm, rather than recognize it for what it is, a taphonomic shift of wing elements. They do not recognize the digitigrade nature of basal pterosaur pedes despite the great match they make with Rotodactylus tracks, the only ichnites with digit 5 impressing far behind the other digits. And the list goes on. As Witton notes above, many current pterosaur workers consider my list of peer-reviewed academic literature unworthy of even considering. If it’s so wrong, it should be easy to dismantle. But to ignore this literature is to keep the blinders on.

And that’s why this blogpost continues…

And Mark Witton, if you’re reading this:
don’t believe anything I write, but please do check out for yourself the Triassic and Jurassic pterosaur specimens and gauge them against the tracks I suggest were made by them.

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