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