Upper Jurassic tidal flat pterosaur tracks from Poland

The following is from an unedited manuscript accepted for publication and pre-published online. The editors note: copyediting may change the contents by the time this is officially published. Not sure why the editors are going this route, except for comment and validation. Hope this gets back to them for the help it offers.

Elgh et al. 2019 report,
“In this paper, we report newly discovered, well-preserved pterosaur track material.”

The authors mistakenly report, 
“Intermediates between most of these states can be seen in the non-pterodactyloid
groups most closely related to the pterodactyloids, e.g. the rhamphorhynchids and wukongopterids” 

No, tiny dorygnathids and scaphognathids are transitional taxa when more taxa are added in the large pterosaur tree (LPT, 238 taxa). Wukongopterids are a sterile lineage, otherwise known as a dead end. There are 4 convergent pterodactyloid-grade clades. All these are recovered by adding taxa without bias.

The authors mistakenly report,
“As noted previously, digit V differs greatly between non-pterodactyloids and pterodactyloids. In non-pterodactyloids this digit is long and supported the uropatagium.”

No, the long and unique fifth digit is found in tanystropheids, langobardisaurids and fenestrasaurs like Cosesaurus and Sharovipteryx. No pterosaur fossil shows uropatagial support. This is a myth. Exceptionally, and for hind wing gliding, each uropatagium extends nearly to the tip of digit 5 in Sharovipteryx.

The authors mistakenly report, 
“Furthermore, pterodactyloids lost their teeth in several lineages, something not seen among nonpterodactyloids.” 

Adding taxa recovers four pterodactyloid-grade clades, as shown by LPT. Two arise from distinct lineages within Dorygnathus. Two others arise from tiny descendants of Scaphognathus. One clade from each lineage produces toothless taxa.

The authors mistakenly report,
“The non-wing bearing digits are much shorter and increase in length from IIII.” 

Typically, yes, but not always. Sometimes all three small phalanges are sub-equal in length.

The authors mistakenly report, 
“Their phalangeal formula is 2-3-4-4, since the wing finger ungual is lost.”

Not true. I have shown many examples of a wing ungual.

The authors mistakenly report, 
“The pes has five digits with a phalangeal formula of 2-3-4-5-2. The penultimate phalanx is elongated in digits I-IV.”

Not true. Pterodaustro (Fig. 1) and several other beach coming pterosaurs do not have elongate penultimate pedal phalanges. The authors cite the invalidated paper by Unwin 1996, rather than Peters 2011, which compared and showed many examples of pterosaur feet and tracks.

Figure 1. A selection of ctenochasmatid feet. Note the short penultimate phalanges (green).

Figure 1. A selection of ctenochasmatid feet from Peters 2011. Note the short penultimate phalanges (green) are not longer than the longest phalanx in series.

The authors mistakenly report,
“The wukongopterids, being the non-pterodactyloid group(s) most closely related to the pterodactyloids have, as with many characters, an intermediate state with a fifth digit that is shorter than in other non-pterodactyloids but longer than in pterodactyloids.”

Not true. Wukongopterids generally have a larger pedal digit 5 than in many other basal pterosaurs and are not related to derived pterosaurs despite several traits that converge. As mentioned above, phylogenetic miniaturization occurred 4 times in the ancestry of the 4 pterodactyloid-grade pterosaurs.

The authors mistakenly report, 
“It is unclear how the fifth digit functioned in terrestrial locomotion in all groups of pterosaurs.” 

Not true. Peters 2000 and 2011 showed exactly how pedal digit 5 was used with comparable tracks and hypothetical perching situations.

To eliminate considering the above issues, the authors report,
“no exhaustive morphometrical methods compare pes and manus impressions with anatomical details to pes and manus body fossils have been made. The most creative attempt to match pes anatomy to tracks by Peters (2011) regrettably introduces too many speculations to be of use in this study.”

That’s how it works, folks. Like Hone and Benton, 2007 and 2009, many pterosaur workers prefer to toss out data that challenges traditions. On the plus side: doing so ensures publication in the present academic climate.

No longer requiring personal examination
of fossils, the authors report, “The Anurognathus ammoni described by Döderlein (1923) was measured using an image of the specimen published by David Hone online (here). The A. ammoni described by Bennett (2007b) was measured using an image published on the pterosaur.net website (here).”

Elgh et al. present several images of
pedal impressions, but they are isolated, so there is no confirmation of left or right identity. This is critical as some pterosaurs have a longest pedal digit 2, while others have a longest pedal digit 3. Others are sub equal. When three ungual bases are collinear most of the time those are digits 2–4, but not always. One Rhamphorhynchus specimen and Nemicolopterus goes the other way.

That statistic has implications for Elgh et al.
who identify four traced fossils with unguals aligned with digit 3 often the longest.

I employ the first photo and first drawing by Elgin et al. (Fig. 2) and find an overlooked pedal morphology (in color overlay) and a strong similarity to an Early Cretaceous Beipiaopterus, a taxon not mentioned in the authors’ current text. Having a pedal digit 1 similar in length to the other three medial toes is very rare, so many other candidates are readily eliminated leaving this one and few to no others. Beipiaopterus nests in the LPT between a series of dorygnathids and a series of pre-azhdarchids, some of them from Solnhofen sediments.

Figure 1. Left and center images from Elgh et al. Colors and pes of Beipiaopterus added for comparison.

Figure 2. Left and center images from Elgh et al. Colors and pes of Beipiaopterus added for comparison.

Elgh et al. made no effort
at locating pedal pads or joints that correspond to pad/joint patterns in pterosaur pedes. By contrast, coloring the track reveals a typical pterosaur pes with a typical pad/joint pattern, but atypical phalanx lengths.

No pterosaur pedes in Peters 2011 are a perfect match,
but Early Cretaceous Beipaiopterus comes close.

Note that Elgh et al. ignored the curved impression
made by the elongate digit 5—because they were married to traditional paradigms, instead of going with the data as is.

I can only wish, at this point,
that future pterosaur workers add more precision to their studies and consider all possibilities… rejecting traditional hypotheses that cannot be validated, while embracing hypotheses that reflect reality.

unedited manuscript accepted for publication:
Elgh E, Pieńkowski G and Niedźwiedzki G 2019. Pterosaur track assemblages from the Upper Jurassic (lower Kimmeridgian) intertidal deposits of Poland: Linking ichnites to potential trackmakers, Palaeogeography, Palaeoclimatology, Palaeoecology, https://doi.org/10.1016/j.palaeo.2019.05.016
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
Peters D 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification. Ichnos 18, 114-141.
Unwin DM 1996. Pterosaur tracks and the terrestrial ability of pterosaurs. Lethaia 29, 373-386.

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