SVP abstracts 9: Pushing a tiny wading pterosaur into the deep end

Habib, Pittman and Kaye 2020
add laser fluorescence to a tiny pterosaur, the still unnamed Berlin specimen, MB.R.3531 (Figs. 1a, b) we first looked at following Flugsaurier 2018.

From the Habib et al. abstract:
“Water launch capacity has been previously suggested for some marine pterosaurs based on osteological grounds, but robust estimates of specimen-specific performance are difficult without robust estimates of wing area and potential hindfoot webbing. Here, we provide the first estimates of pterosaur water launch performance that take into account preserved soft tissue anatomy.”

FIgure 1. Reconstruction of MB.R.3531, nesting with Eoazhdarcho, Eopteranodon and Aurorazhdarcho.

FIgure 1a. Reconstruction of MB.R.3531, nesting with Eoazhdarcho, Eopteranodon and Aurorazhdarcho. Shown about actual size, so this pterosaur could have stood upright like this in a 10cm per side box. See figure 1b.

Figure 1. Aurorazhdarcho primordial and the smaller Aurorazhdarcho micronyx to scale.

Figure 1b. Aurorazhdarcho primordial and the smaller Aurorazhdarcho micronyx (not a juvenile) to scale. The smaller one had better stay out of deeper waters.

Continuing from the Habib et al. abstract:
“The aurorazhdarchid pterosaur specimen MB.R.3531 from the Upper Jurassic Solnhofen Limestone was imaged using Laser-Stimulated Fluorescence, revealing significant soft tissue preservation. These soft tissues are among the best-preserved of any known Jurassic pterosaur, including for the first time, a complete actinofibrillar complex, an undistorted actinopatagium with the retrophalangeal connective tissue wedge and entire trailing edge, and webbed feet.”

Why the showmanship (= hyperbole, = falsehood)? Most of these traits have been known for several pterosaurs and from less jumbled specimens, including the  Zittel wing specimen of Rhamphorhynchus (Fig. 2), the dark-wing specimen of Rhamphorhynchus and the Vienna specimen of Pterodactylus (Fig. 3).

The Zittel wing

Figure 2. The Zittel wing from a species of Rhamphorhynchus. This is real. There is no way this wing membrane is going to stretch to the ankles. See figure 3 for comparison and phylogenetic bracketing. This is how pterosaur wings were able to be folded away when not in use. 

Figure 2. Here is the Vienna specimen of Pterodactylus in situ and with matrix removed. Now compare this figure with figure 3, which shows the wings and uropatagia unfolding. There is no way to turn this into a deep chord wing membrane. And it decouples the forelimbs from the hind limbs.

Figure 3. Here is the Vienna specimen of Pterodactylus in situ and with matrix removed. Now compare this figure with figure 3, which shows the wings and uropatagia unfolding. There is no way to turn this into a deep chord wing membrane. And it decouples the forelimbs from the hind limbs. This is how pterosaur wings were able to be folded away when not in use. 

Continuing from the Habib et al. abstract:
“These physically validated soft tissues formed the basis for analyzing water launch capability in MB.R.3531. We modeled the water launch as quadrupedal and broadly similar to modern “puddle jumping” anseriform birds that use a combination of their webbed feet and partially folded wings to push against the water surface during takeoff.”

More myth-making. Like the morphologically similar by convergence, Pterodactylus (based on the Vienna specimen; Figs. 3, 4), MB.R.3531 was a quadrupedal wader (note the tiny fore claws), but able to stand bipedally prior to take-off. Waders don’t get themselves into water too deep to touch the substrate. Ask any sandpiper, plover or stilt.

So this is much ado about nothing, based on putting the discredited Habib method of pushup take-off back on the table.

FIgure 6. Pterodactylus scolopaciceps (n21) model. Full scale.

Figure 4. Pterodactylus scolopaciceps (n21) model. Full scale. This is how pterosaur wings were able to be folded away when not in use. 

More from the Habib et al. abstract:
“Under this model, both hind limb and forelimb contact areas are critical. Under conservative assumptions regarding power and range of motion, we predict that MB.R.3531 was capable of rapid takeoff from the water surface.

Yes, of course, but from a bipedal start (Fig. 5). And from shallow ponds, no deeper than knee deep.

FIgure 8. Dimorphodon take off (with the new small tail).

FIgure 5. Dimorphodon take off (with the new small tail).

From the Habib et al. abstract:
“Our model predicts that water launch performance in pterosaurs was particularly sensitive to three factors: available propulsive contact area, forelimb extension range, and extension power about the shoulder. MB.R.3531 possessed both osteological and soft tissue features that significantly enhanced these performance characteristics (including, but not limited to, expanded internal rotator/extensor attachments on the proximal humerus, extended humeral length, chordwise distal actinofibril orientation, and webbed pes).”

If you’ll compare one with another, MB.R.3531 (Fig. 1) is convergent in most respects to a typical Solnhofen Pterodactylus (Fig. 4), down to the webbed feet. There was nothing out of the ordinary about MB.R.3531.

“These features would have limited impact on flight performance. We therefore interpret them as likely water takeoff specializations.

Whoa, partner! These traits are typical of most beach combing pterosaurs, so far as they can be determined in fossils and phylogenetic bracketing, even with unrelated clade convergence.

“The osteological specializations in MB.R.3531 are subtle, which may be related to its small size.”

I would agree that the osteological specializations are so subtle they do not exist.

“Larger marine pterosaurs appear to exaggerate these characteristics, which matches expectations from scaling.

This is false. Ornithocheirids have notoriously tiny feet, unsuitable for anything more than standing still and walking slowly. More to come.

“We show that soft tissue data can be used to help validate the dynamic feasibility of water launch in pterosaurs, suggesting it was a regular part of foraging behavior in some taxa.”

This is false. Dr. Habib, just let the pterosaur stand upright, as its ancestors did and as it was designed to do (fused sacrals and fused dorsal vertebrae dorsally, sternum + gastralia + prepubes support ventrally). Quadrupedal pterosaur tracks are more prevalent because they were made by a few clades of small-fingered beach combing pterosaurs, principally pterodactylids, ctenochasmatids and azhdarchids (Peters 2011).

Pelican take-off sequence from water.

Figure 6. Pelican take-off sequence from water using kicking webbed feet and elevated, then flapping wings simultaneously. Click to enlarge.

From an earlier 2018 assessment of MB.R.3531:
Habib and Pittman 2018 bring us a rarely studied Berlin pterosaur, MB.R.3531 (Fig. 1) originally named Pterodactylus micronyx, then Aurorazhdarcho micronyx. This specimen nests with other wading pterosaurs, AurorazhdarchoEopteranodon and Eoazhdarcho forming  a clade overlooked by other workers, at the transition between germanodactylids and pteranodontids, not related to azhdarchids (Peters 2007).

For those wondering why I don’t publish more.
Why put in the effort if competing studies are ignored? The online way is faster, briefer and can be animated with no color charges. Furthermore, the vetting process prior to publication of hypotheses like the dangerous pushup launch and the bat-wing pterosaur membrane myth, is failing time and again. Editors, professors and researchers who should be earning their paycheck from rigorously testing new hypotheses are instead granting their friends free passes in an effort to keep the status quo in lectures and textbooks.


References
Habib M and Pittman M 2018. An “old” specimen of Aurorazhdarcho micronyx with exceptional preservation and implications for the mechanical function of webbed
feet in pterosaurs. Flugsaurier 2018: The 6th International Symposium on Pterosaurs. Los Angeles, USA. Abstracts: 41–43.
Habib MB, Pittman M and Kaye T 2020. Pterosaur soft tissues revealed by laser-stimulated fluorescence enable in-depth analysis of water launch performance. SVP abstracts 2020.
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
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. http://dx.doi.org/10.1080/10420940.2011.573605

https://pterosaurheresies.wordpress.com/2018/03/23/pteranodon-quad-hopping-water-takeoff-according-to-the-amnh/

https://pterosaurheresies.wordpress.com/2018/08/12/flugsaurier-2018-web-footed-little-pterosaur-mb-r-3531/

https://pterosaurheresies.wordpress.com/2012/12/16/water-takeoff-in-a-pelican-part-2-with-reference-to-pterosaur-water-takeoffs/

https://pterosaurheresies.wordpress.com/2015/03/23/amnh-animated-pterosaur-takeoffs/

https://pterosaurheresies.wordpress.com/2012/04/07/pterosaur-take-off-from-water/

https://pterosaurheresies.wordpress.com/2013/12/06/pterosaurs-were-unlikely-floaters-hone-and-henderson-2013/

https://pterosaurheresies.wordpress.com/2015/05/23/pterosaur-launch-talk-from-2012-on-youtube/

Upper Jurassic tidal flat pterosaur tracks from Poland

Note:
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.

Below
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.


References
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.

Earliest Cretaceous pterosaur tracks from Spain

Pascual-Arribas  and Hernández-Medrano 2016
describe new pterosaur ichnites from La Muela, near Soria, Spain.

From the abstract
“Pterosaurs tracks in the Cameros basin are plentiful and assorted. This fact has allowed to define several Pteraichnus ichnospecies and moreover to distinguish other morphotypes. The study of the new tracksite of La Muela (Soria, Spain) describes Pteraichnus cf. stokesi ichnites that is an unknown ichnospecies until now and that confirms the wide diversity of this type of tracks in the Cameros Basin. Their characteristics correspond to the ones of the Upper Jurassic track sites of United States. Similar tracks have already been described in other tracksites, both inside and outside the Iberian Peninsula during the Upper Jurassic-Lower Cretaceous transit. Because of their shape and morphometrical characteristics they can be related to the pterosaurs of the Archaeopterodactyloidea clade. The analysis of this ichnogenus indicates the need for a deep review because encompasses ichnites with a big variety of shapes and morphometric characteristics.”

Figure 1. La Muela pterosaur manus and pes tracks, plus tracing and sister ichnotaxa among basalmost ctenochasmatids.

Figure 1. La Muela pterosaur manus and pes tracks, plus tracing and sister ichnotaxa among basalmost ctenochasmatids. Note the extreme length of manus digit 1. This may result from secondary and further impressions during locomotion. Such an extension is no typical. Ctenochasmatids have shorter fingers and claws.

By adding the traits of the La Muela track
to the large pterosaur tree (LPT, 233 taxa) it nested precisely between stem ctenochasmatids and basalmost ctenochasmatids.

Why guess when a large database already exists?
That’s why I published the pterosaur pes catalog with Ichnos in 2011.

Those manus tracks are rather typical for pterosaurs.
Impossible for archosaurs. Typical for lepidosaurs, which have looser metacarpophalanageal joints.

Pascual-Arribas and Hernandez-Medrano
draw triangles, Y-shapes and rectangles around Ctenochasma, azhdarchid and Pterodaustro tracks. Since the triangle and rectangle taxa are sisters, this nearly arbitrary geometrical description is of little phylogenetic use. Ctenochasmatids can spread and contrast their metatarsals, so they can change their pes from one ‘shape’ to another.

A second paper on Spanish ptero tracks
by Hernández-Medrano et al. 2017 describe more tracks. In the first paper, some pterosaur pedes were correctly attributed to Peters 2011. The same illustrations in the second paper were attributed to the authors of the first paper. :  )

References
Hernández-Medrano N, Pascual-Arribas C and Perez-Lorente F 2017. First pterosaur footprints from the Tera Group (Tithonian–Berriasian) Cameros Basin, Spain. Journal of Iberian Geology DOI 10.1007/s41513-017-0020-8. (in English)
Pascual-Arribas C and Hernández-Medrano N 2016. Huellas de Pteraichnus en La Muela (Soria, España): consideraciones sobre el icnogénero y sobre la diversidad de huellas de pterosaurios en la Cuenca de Cameros. (Pteraichnus tracks in La Muela (Soria, Spain): considerations on the ichnogenus and diversity of pterosaur tracks in the Cameros Basin.) Revisita de la Sociedad Geologica de España 29(2):89–105. (in Spanish)
Peters D 2011. A catalog of pterosaur pedes for trackmaker identification. Ichnos, 18: 114–141.

 

Giant Alaska pterosaur tracks indicate floating pterosaurs

Figure 1. Pterosaur tracks from Alaska. Note the lack of pedal tracks and the large size of the manus tracks.

Figure 1. Pterosaur tracks from Alaska. Note the lack of pedal tracks and the large size of the manus tracks.

Figure 2. Closeup of a giant pterosaur manus track. Digits identified.

Figure 2. Closeup of a giant pterosaur manus track. Digits identified.

A recent paper ( ) described giant Late Cretaceous pterosaur tracks from the far north in Alaska. These are likely made by large azhdarchids, like Quetzalcoatlus.

At 18 centimeters long by 6 centimeters wide, the bigger pterosaur tracks are “very large” compared to others that have been reported, Fiorillo’s team says.

The more diminutive set of prints, meanwhile, was only about one-fourth as large — about 6 centimeters by 4 centimeters.

Manus only tracks were likely produced by floating and poling pterosaurs as we talked about earlier with Tapejara. Here the size and proportions of the manus tracks, along with the location and time period all point toward giant azhdarchids.

Figure 1. The azhdarchid pterosaur Quetzalcoatlus floating and poling producing manus only tracks.

Figure 3. The azhdarchid pterosaur Quetzalcoatlus floating and poling producing manus only tracks.

It is important to appreciate the great size of the pterosaurs that made such large manus tracks, especially so since the fingers that made the impressions are among the smallest parts on the pterosaur itself.

Figure 1. Quetzalcoatlus specimens to scale.

Figure 4. Quetzalcoatlus specimens to scale. Here digit 3 is approximately 18 cm long, matching the size of the track. The manus of Quetzalcoatlus is poorly known. These are based on Zhejiangopterus and Azhdarcho. The second finger could have been shorter to match the tracks. The ability of digit 3 to rotate posteriorly harkens back to the lepidosaur ancestry of pterosaurs.

Manual 3.1 of Azhdarcho (Fig. 4) shows how that digit was able to bend posteriorly. Like most lizards, the fingers were rather free to rotate on bulbous articular surfaces.

Figure 2. Manual 3.1 for Azhdarcho. Note the bulbous proximal portion.

Figure 5. Manual 3.1 for Azhdarcho. Note the bulbous proximal portion enabling posterior bending.

 

References
Fiorillo AR et al. 2009. A pterosaur manus track from Denali National Park, Alasak range, Alaska, United States. Palaios 24: 466-472.

Fiorillo AR et al. 2014. Pterosaur tracks from the Lower Cantwell Formation (Campanian–Maastrichtian) of Denali National Park, Alaska, USA, with comments about landscape heterogeneity and habit preference. Historical Biology DOI:10.1080/08912963.2014.933213

Online report.

 

New dsungaripterid (?) walking track

A new large pterosaur track
attributed to a dsungaripterid has been published (He et al. 2013, Fig. 1).

Unfortunately,
I know of only one dsungaripterid pes, that of Noripterus

Fortunately,
it’s a pretty good match. I suspect that much more is known of another dsungaripterid, Dsungaripterus, but the pes and manus have not been published yet. Send that data if you have it.

Other related taxa
from the Tapejaridae, like Huaxiapeterus and Tapejara, have very similar pedal proportions, but a longer manual digit 1. They are still possible candidates.

 

Figure 1. New possible dsungaripterid track *He et al. 2013) compares favorably to Noripterus, a dsungaripterid pterosaur. Note the metatarsal spread and likely finger 3 drag mark. The metatarsophalangeal joints must have been very loose to enable the wide splay seen in the track. Also note the precision of the pes versus the expansion of the manus track.

Figure 1. Click to enlarge. New possible dsungaripterid track (He et al. 2013) compares favorably to Noripterus, a dsungaripterid pterosaur. Note the metatarsal spread and likely finger 3 drag mark. The metatarsophalangeal joints must have been very loose to enable the wide splay seen in the track. Also note the precision of the pes versus the expansion of the manus track.

Since footprints are so plastic during their creation,
some are very difficult to identify. Nevertheless, these impressions are impressive! He et al (2013) did not illustrate the ungual of digit 4, so if there was no ungual, or if the ungual extended only as far as the impression indicates (Fig. 1), then different taxa become candidates (those with a short digit 4), not dsungaripterids or tapejarids.

The manus
of Noripterus essentially matches the printmaker in having a very short, slender  digit 1 and a large robust digit 3 with p3.2+p3.2 shorter in sum than p3.1. Again, I have no manus data for Dsungaripterus. Send it if you do.

Manus vs pes impression
Here the pes impression shows more detail than the manus. Moreover, the manus impression is quite fat compared to the slender finger bones. Why is this so? If you just look at the skeleton it appears that there is no room for that much flesh around digit 3. But data is data. Could the method of implantation of the manus, with a little more speed perhaps, create a little  crater around it? Or did the manus shift laterally during the step cycle contact? Whatever the answer, such impressions are common to a wide range of quadrupedal pterosaur trackmakers.

References
He Q, Xing L, Zhang J, Lockley MG, Klein H, Persons S4, Qi L and Kia C 2013. New Early Cretaceous Pterosaur-Bird Track Assemblage from Xinjiang, China: Palaeotheolgy and Palaeoenvironment. Acta Geologica Sinica (English Ed.) 87(6):1477-1485. pdf

Pterosaurs were likely floaters: evidence from manus only tracks

Yesterday we reviewed Hone and Henderson (2013) who conducted computational experiments with four misbegotten digital pterosaur models and reported that pterosaurs were unlikely floaters that would have struggled to keep their noses above the surface and so risked drowning, despite their air-filled skeletons.

Unfortunately
the Hone and Henderson results don’t agree with the facts as told by manus-only tracks, that can only be made by floating pterosaurs. As Hone has done in previous papers, these are all conveniently omitted. Case in point: the Summerville tracks (Lockley et al. 1996, Fig. 1).

Summerville tracks matched to potential trackmaker, Jidapterus, a basal azhdarchid.

Figure 1. Summerville tracks matched to potential trackmaker, Jidapterus, a basal azhdarchid pterosaur using a poling technique to produce manus-only tracks while floating.

Summerville (Late Jurassic) manus only tracks (Fig 1), likely made by a sister to Jidapterus, a protoazhdarchid with rather big fingers.

Is this the only explanation?
Oh, sure some have said that pterosaurs pressed their hands more deeply into the matrix and footprints were thereafter erased by geological processes. But doesn’t this strike you as trying to make excuses, on the order of Elgin, Hone and Frey’s infamous “membrane shrinkage“?

Figure 2. Manus only tracks of pterosaurs, Late Jurassic to Late Cretaceous.

Figure 2. A catalog of manus only tracks of pterosaurs, Late Jurassic to Late Cretaceous. Note the odd and large Las Hoyas track is now considered to be made by a theropod, which makes perfect sense.

The large Las Hoyas track
is impossible to fit to a pterosaur manus. No pterosaur has a longer and more robust manual digit 2 than 3. Some have these two digits subequal in length, but to scale these up to the track size creates a truly gigantic pterosaur. Vullo et al. 2009 got it right when they decided it belonged to a theropod dinosaur foot.

Figure 4. Tapejara compared to Albian tracks from South America. They are a close match in size and shape.

Figure 4. Tapejara compared to Albian tracks from  west-central Argentina (Calvo and Lockley 2001). They are a close match in size and shape. Pedal digits 2-4 are subequal and digit 1 is slightly shorter. Scale bars for tracks and pterosaur match. Footprints indicate no splay in the digits. Note the comparative sizes of the manus and pes.

The “first Gondwana pterosaur tracks” (Calvo and Lockley 2001) can all be matched to Tapejara-like (Fig. 4, 5) trackmakers. The Candeleros Member of the Rio Limay Formation (Albian–Cenomanian) at Lake Ezequiel Ramos Mexía, Neuquén Province, Argentina is contemporary with Tapejara bones on the east coast of Brazil. The palaeoenvironmental setting of the track beds was a lake shoreline, where dinosaur tracks also occur.

Figure 5. Tapejara poling while floating, producing manus-only tracks, all to scale.

Figure 5. Tapejara poling while floating, producing manus-only Albian tracks from west-central Argentina, all to scale .

Above, manus only tracks (Calvo and Lockley 2001) matched to Tapejara.

Figure 5. Price (Utah, Maastrichtian) tracks. These match up pretty well to Cycnorhamphus, except for size. Luckily we know of giant cycnorhamphids like Moganopterus, shown as a skull here to scale.

Figure 5. Price (Utah, Maastrichtian) tracks. These match up pretty well to Cycnorhamphus, except for size. Luckily we know of giant cycnorhamphids like Moganopterus, shown as a skull here to scale. Unfortunately, Moganopterus is from the Early Cretaceous of China.

Moganopterus, a cycnorhamphid, is a good model for the trackmaker of the Maastrichtian Price (Utah) racks, merely with a shorter digit 2 than Cycnorhamphus (Fig. 5). Unfortunately Moganopterus is from the Early Cretaceous of China.

If you’re interested
in finding a better match for any of these tracks, you are welcome to try. I had a catalog of pterosaur manus and pedes at reptileevolution.com and a matrix of pterosaur traits that made my search go rather quickly.

References
Calvo JO and Lockley MG 2001. The first pterosaur tracks from Gondwana. Cretaceous Research 22:585-590.
Elgin RA, Hone DWE and Frey E 2011. The extent of the pterosaur flight membrane. Acta Palaeontologica Polonica 56 (1), 2011: 99-111. doi: 10.4202/app.2009.0145
Hone DWE, Henderson DM 2013. The posture of floating pterosaurs: Ecological implications for inhabiting marine and freshwater habitats, Palaeogeography, Palaeoclimatology, Palaeoecology (2013 accepted manuscript), doi: 10.1016/j.palaeo.2013.11.022
Lockley MG, Logue TJ, Moratalla JJ, Hunt AP, Schultz RJ and Robinson JW 1995.  The fossil trackway Pteraichnus is pterosaurian, not crocodilian: implications for the global distribution of pterosaur tracks. Ichnos, 4: 7–20.
Lockley MG, Hunt AP and Lucas SG 1996. Vertebrate track assemblages from the Jurassic Summerville Formation and correlative deposits. – In: Morales M. (Ed.), The Continental Jurassic. Museum of Northern Arizona Bulletin, 60: 249–254.
Lockley MG and Wright JL 2003. Pterosaur swim tracks and other ichnological evidence of behavior and ecology. – In: Buffetaut E and Mazin JM (Eds), Evolution and Paleobiology of Pterosaurs; Geological Society, London, Special Publications 217:297-313.
Lockley M, Harris JD and Mitchell L 2008. A global overview of pterosaur ichnology: tracksite distribution in space and time. Zitteliana B28: 185-198.pdf
Mickelson DL, Lockley MG, Bishop J, Kirkland J 2004. A New Pterosaur Tracksite from the Jurassic Summerville Formation, Near Ferron, Utah. Ichnos, 11:125–142, 2004
Parker L and Balsley J 1989. Coal mines as localities for studying trace fossils. In: Gillette DD and Lockley MG (Eds), Dinosaur Tracks and Traces; Cambridge (Cambridge University Press), 353–359.
Pascual Arribas C and Sanz Perez E 2000. Huellas de pterosaurios en el groupo Oncala (Soria España). Pteraichnus palaciei-saenzi, nov. ichnosp.  Estudios Geologicos, 56: 73–100.
Vullo R, Buscalioni A D, Marugán-Lobón J and Moratalla JJ 2009. First pterosaur remains from the Early Cretaceous Lagerstätte of Las Hoyas, Spain: palaeoecological significance. Geological Magazine, 146: 931-936.

Prorotodactylus and Rotodactylus: Produced by a Dinosauromorph Archosaur or a Lepidosaur?

There were some strange footprints
in the Early and Middle Triassic in the Holy Cross Mountains of Poland. These are covered in a new paper by Niedzwiedski et al. (2013). They report, “The first body fossil evidence of dinosauromorphs is a few million years younger than the youngest Polish tracks, so Prorotodactylus and Rotodactylus tracks currently provide the oldest record of dinosauromorph morphology, biology and evolution. Here, in this monographic treatment, we provide a detailed documentation of the Polish Prorotodactylus  and Rotodactylus record from the late Early (Olenekian) early Middle (Anisian) Triassic.”

Peabody (1948) introduced us to Rotodactylus from the Moenkopi formation. Haubold (1966, 1967) cataloged several types.

Prorotodactylus“Diagnosis (based on Ptaszyn´ski 2000a; Brusatte et al. 2011; Klein & Niedz´wiedzki 2012). Long striding trackways with small lacertoid pentadactyl pes and manus imprints. Manus overstepped laterally by the pes. Pes outwardly and manus inwardly rotated with respect to the midline. Digitigrade pes with digits I–IV increasing in length, II–IV subparallel and tightly ‘bunched’ with distinct straight metatarsal–phalangeal axis (i.e. straight posterior margin of the preserved digit imprints), digit I everted. Digit V rarely impressed, and if present, located in a posterolateral position and relatively short in comparison to digits I–IV. Manus semiplantigrade or plantigrade, of chirotheroid shape, compact and rounded with posterolaterally positioned digit V mostly impressed. Digit III longest, followed by IV, II and I, which is shortest. The main difference between Prorotodactylus and Rotodactylus is the position and shape of digits V in both the manus and pes imprints of Prorotodactylus.”

Figure 1. Click to enlarge. Chronology of ichnites, from Niedzwieczki et al. 2013. My notes in red. Blue ichnites have been flipped for consistency (now they're all righties, no lefties). Note the middle traces include a manus in which digit 4 is longer than 3, distinct from the others, but overlooked by Niedzwieczki et al. 2013.

Figure 1. Click to enlarge. Chronology of ichnites, from Niedzwieczki et al. 2013. My notes in red. Blue ichnites have been flipped for consistency (now they’re all righties, no lefties). Note the middle traces include a manus in which digit 4 is longer than 3, distinct from the others, but overlooked by Niedzwieczki et al. 2013.

Unfortunately,
The only derived and small archosauriforms with pedal digit 4 longer than 3 include lagerpetids, like Tropidosuchus and Lagerpeton (Fig. 4), two taxa not related to dinos, according to the large reptile tree. Neither these two nor its closest sister, Chanaresuchus, has pedal digit 5. None of these three preserved the manus. Metatarsal and phalangeal proportions do not match the ichnite either. You have to go all the way back to Proterosuchus to find an archosauriform with pedal digit 4 longer than 3, a plesiomorphic trait of basal reptiles.

The combination of manus digit 3 > 4 and pedal digit 4 > 3 is the key to discovering the trackmaker of Prorotodactylus. Here we’ll find that very few taxa are a good match for Rotodactylus and Prorotodactylus ichnites. Several have that formula, but few have the much smaller manus and short fingers.

Figure 2. Click to enlarge. Among the few taxa that have a longer manual digit 3 than 4 AND a longer pedal digit 4 than 3 include Owenetta, Emeroleter, Sphenodon, Cosesaurus and Tanystropheus.

Figure 2. Click to enlarge. Among the few taxa that have a longer manual digit 3 than 4 AND a longer pedal digit 4 than 3 include Owenetta, Emeroleter, Sphenodon, Cosesaurus and Tanystropheus.

And more here:

More reptiles with the unusual manual digit 3 longer than 4 AND pedal digit 4 longer than 3.

Figure 3. More reptiles with the unusual manual digit 3 longer than 4 AND pedal digit 4 longer than 3 include the basal lizards, Liushusaurus and the Daohougo lizard, plus Lazarussuchus. None of these taxa were even considered by Niedzwiedski et al. (2013).

Niedzwiedski et al. (2013) in their quest for a trackmaker to fit Rotodactylus published this image of Lagerpeton, which is an obvious mismatch that doesn't even have a pedal digit 5.  Plenty of other taxa are better matches (Figs. 3,4) but those weren't published, tested or promoted.

Figure 4. Niedzwiedski et al. (2013) in their quest for a trackmaker to fit Rotodactylus published this image of Lagerpeton, which is an obvious mismatch that doesn’t even have a pedal digit 5. And the pedal digit 5 impression does not include an ungual (Peabody 1948). The ungual impression was added with hope, not data. Plenty of other taxa are better matches (Figs. 3,4) but those weren’t published, tested or promoted.

To their credit,
Niedzwiedski et al. (2013) reported, “As Lagerpeton is only known from South America and the Ladinian, it is unlikely that this particular genus was responsible for the Polish footprints. Furthermore, there are specific differences between the foot skeleton of Lagerpeton and the Prorotodactylus and Rotodactylus footprints. Our argument, however, is not that Lagerpeton itself made the Polish footprints, but rather that the Prorotodactylus and Rotodactylus tracks were made by a non-dinosaurian dinosauromorph closely related to, and sharing derived characters with, Lagerpeton.”

Talk about bad science. 
You can see by the above confession that Niedzwiedski et al. (2013) agreed this was a bad match. So why did they promote this? And only this? This is the core result of their entire paper and its predecessor (Brusatte et al. 2011). They also virtually ignored and dismissed the absolutely perfect match provided by Peters (2000, Fig. 6). They also ignored every other taxon that could have made these tracks (Figs, 2,3) better than Lagerpeton. Evidently, someone had a point to prove, and doggone it, facts were not going to get in the way of this hypothesis!

The best matches to Prorotodactylus and Rotodactylus. In this case, something between a small Tanystropheus and an even smaller Cosesaurus provides the best matches in all regards.

Figure 5. The best matches to Prorotodactylus and Rotodactylus. In this case, something between a small Tanystropheus and an even smaller Cosesaurus in the digitigrade configuration provides the best matches in all regards. These taxa were not even mentioned by Niedwiedcki et al. (2013). Skeletal fossils are known from geographically and chronologically similar sediments. Both of these taxa are tritosaur lizards, not archosaurs and not protorosaurs and certainly not non-archosaur archosauriforms. Other sister candidates include langobardisaurs, which also have a wide distribution.

Niedzwiedski et al. (2013) refer to Brusatte et al. (2011) supplementary materials for further explanations regarding trackmaker selection. Unfortunately they had their bias blinders on. They did not include any lizards, but focused only on their favorite archosaurs.

Niedzwiedski et al. (2013) grant, “Some other recent authors have presented alternative identifications of the Rotodactylus trackmaker. Lockley & Hunt (1995) considered the trackmaker to be a lepidosauromorph with a specialized gait. Peters (1996, 1997) briefly discussed (in abstracts) a potential close relationship between Rotodactylus and pterosaurs, while Peters (2000) identified Rotodactylus as being made by a nonarchosaurian archosauromorph.” (BS! I said it was a perfect match to Cosesaurus, which is not a nonarchosaurian archosauromorph! I’ve never used that term. See how twisted paleontologists can get? (more examples here and here). It’s shameful and creepy.)

Niedzwiedski et al. (2013) report, “Regardless of the precise affinities of Rhynchosauroides, a lepidosauromorph or non-archosaurian archosauromorph would not be expected to possess footprints that formed narrow gauge trackways and are consistently digitigrade, with reduced outer digits and tightly bunched central digits.” [See the bias! The Jayne labs prove that fast-moving lizards are narrow-gauge and digitigrade. And these were no ordinary lepidosaurs. They were well on their way toward bipedal locomotion. This group certainly did not exhaust the possibilities (Figs. 3, 4). They kept their blinders on. Now I know exactly how Branch Rickey felt when others were verbally attacking his best ballplayers!] Just because the taxa I promote come from the other side of reptile family tree doesn’t mean they can’t play.

Cosesaurus matched to Rotodactylus from Peters 2000.

Figuure 6. Cosesaurus matched to Rotodactylus from Peters 2000. This a perfect match with no imagination or excuses added. Why didn’t Niedwiedski et al. (2013) acknowledge this? They obviously had a preset agenda. Their conclusions ruled their data. Dinosaurs are cool, they make the news. Cosesaurus, fenestrasaurs, tritosaurs are bench players in their mind, not worth considering. The proximal pahalanges were elevated because the metatarsophalangeal joint was a butt joint, retained by the pterosaur Dimorphodon(?) weintraubi, among other sister taxa.

Niedzwiedski et al. (2013) report, “Furthermore, a pterosaur identification for the Polish tracks is also unlikely, because the feet of Triassic pterosaurs retain elongate pedal digits I and V, unlike dinosauromorphs, and the digits are splayed distally, unlike the tracks of Prorotodactylus and Rotodactylus and the feet of Lagerpeton (e.g. Wild 1978; Dalla Vecchia 2009).”

The patron saint of "No Respect", Rodney Dangerfield.

Figure 8. The patron saint of “No Respect”, Rodney Dangerfield.

This is a red-herring!
Niedzwiedski et al. (2013) argued against something that wasn’t even promoted. Peters (2000) matched Cosesaurus to Rotodactylus because it is a good match! Yes, pterosaurs descended from Cosesaurus and basal forms made similar tracks (Peters 2011), with pedal digit 5 impressing behind the other four digitigrade digits, sometimes splayed, sometimes not. So, why would good paleontologists turn a blind eye to all the best possibilities and force fit a bad match to their discovery?

I keep asking myself the same thing almost every day I write this blog. Unfortunately, this sort of thing happens all the time. For now it’s just grist for the mill.

ADDENDUM
The following was added after original publication. These are examples of how pedal digit 5 operated in basal pterosaurs. Note the impression varies from a single round knuckle impression far behind the digits to a complete phalanx impression (Peters 2011, will send on request).

Digitigrade pterosaur pedes. This is how pedal digit 5 worked in pterosaur taxa with a pedal digit 5. We have ichnites that match anurognathid pedes. See them in the digitigrade pterosaur pedes post linked in the text.

Addendum figure: Digitigrade pterosaur pedes. This is how pedal digit 5 worked in pterosaur taxa with a pedal digit 5. We have ichnites that match anurognathid pedes. See them in the digitigrade pterosaur pedes post linked in the text. PILs (parallel interphalangeal lines are easy to gauge here).

I also encourage you to check out an earlier post on digitigrade pterosaur pedes.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Brusatte SL, Niedz´wiedzki G and Butler RJ 2011. Footprints pull origin and diversification of dinosaur stem lineage deep into Early Triassic. Proceedings of the Royal Society B, 278, 1107–1113.
Haubold H 1966. Therapsiden- und Rhynchocephalien-Fahrten aus dem Buntsandstein Sudthuringens: Hercynia, N. F., v. 3, p. 147-183.
Haubold H 1967. Eine Pseudosuchier-Fahrtenfauna aus dem buntsanstein Sudthurigens: Hall. Jb. Mitteldt. Erge, v. 8, p. 12-48.
Niedzwiedzki G, Brusatte SL and Butler RJ 2013. Prorotodactylus and Rotodactylus tracks: an ichnological record of dinosauromorphs from the Early–Middle Triassic of Poland. Geological Society, London, Special Publications, first published April 23, 2013. doi 10.1144/SP379.12
Peabody FE 1948.  Reptile and amphibian trackways from the Lower Triassic Moenkopi formation of Arizona and Utah.  University of California Publications, Bulletin of the  Department of Geological Sciences 27: 295-468.
Peters D 2000. 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(2):114-141. http://dx.doi.org/10.1080/10420940.2011.573605.

Summerville Ptero Tracks – Mickelson et al. 2004

Mickelson et al. (2004) described new pterosaur tracks from the Late Jurassic Summerville Formation in Utah. From their paper: “Footprint length varies from 2.0 to 7.0 cms. The ratio of well-preserved pes:manus tracks is about 1:3.4. This reflects a bias in favor of  preservation of manus tracks due to the greater weight-bearing role of the front limbs, as noted in other pterosaur track assemblages. The sample also reveals a number of well-preserved trackways including one suggestive of pes-only progression that might be associated with take off or landing, and another that shows pronounced lengthening of stride indicating acceleration. However, traces of a fifth pes digit suggest some tracks are of rhamphorynchoid rather than pterodactyloid origin, as usually inferred for Pteraichnus.”

Let’s take a closer look at which pterosaur might have made these tracks.

pterosaur tracks (pteraichnus ichnites)

Figure 1. A series of pterosaur tracks from Mickelson et al. (2004). Impressions made at the same time are colored the same. Note the distance between left manus and right pes is quite short, as if the pterosaur walked quite upright. Note the length of digits 1-4. It is rare that a pterosaur foot includes such a long digit 1. Pink arrow points to pedal track that includes fifth digit impressions.

The relative length of pedal digit 1 is typically shorter than digit 2 in pterosaurs. However, in a few, digit 1 is as long or nearly as long as the other digits, as shown in the Figure 1. The relative length of digit 4 is also not typical. Apparently the metatarsus was not closely appressed as divisions extend to the heel. Together these greatly reduce the list of possible trackmakers to Beipiaopterusn44, and possibly Huanhepterus and the closely related flightless pterosaurs.  Pterodaustro has a similar foot, but the manus is much smaller than in the Summerville tracks. The Crato “azhdarchide” (SMNK PAL 3830) also had coequal pedal digits, but the huge unguals are not good matches. Tiny Nemicolopterus has a similar pes but was half the size.

My guess is these tracks represent the concurrent flightless pterosaur mislabled Mesadactylus (Smith et al. 2004), which preserves neither manus nor pes. As in the more completely known flightless pterosaur, SoS 2428, the manual digits are quite asymmetrical. Unfortunately, the feet are the only part of the flightless pterosaur that remain unknown.

So, this guess is based entirely on phylogenetic bracketing, restoration, chronology and size, all close matches.

The relative positions of the left manus and right pes (Fig. 1) indicate an upright posture when walking (Fig. 2) rather than the more horizontal configuration favored by traditional paleontologists (Fig. 3).

I can’t say much about the progression of accelerating tracks, mentioned by Mickelson et al. (2004), other than it supports the bipedal take-off model, rather than the disputed forelimb take-off model.

Pterodactylus walk matched to tracks according to Peters

Figure 2. Click to animate. Plantigrade and quadrupedal Pterodactylus walk matched to Crayssac tracks

Walking pterosaur according to Bennett

Figure 3. Click to animate. Walking pterosaur according to Bennett. This is the traditional model. Note the forelimbs provide no forward thrust, but merely act as props.

A preponderance of manus-only tracks might represent floating pterosaurs poling through shallow waters.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Mickelson DL, Lockley MG, Bishop J, Kirkland J 2004. A New Pterosaur Tracksite from the Jurassic Summerville Formation, Near Ferron, Utah. Ichnos, 11:125–142, 2004