Small Late Cretaceous pterosaur tracks from Korea: close to Sinopterus

Jung et al. 2021 (preprint)
published several well-preserved, but jumbled, small (5cm) manus and pes pterosaur tracks. The authors considered the tracksite important due to its late age (Turonian, Late Cretaceous) and small tracks, perhaps unexpected by the authors.

From the Jung et al. abstract:
“The pterosaur track assemblage, assigned to Pteraichnus isp., consists of various sized, randomly oriented manus-dominated tracks with several pes claw marks. These features commonly indicate the semi-aquatic behavior and multi-age gregariousness of pterosaurs. The supposed trackmaker of pterosaur tracks would be the small-sized pterodactyloid that inhibited the Late Cretaceous Korean Peninsula, but that has not previously been reported.”

Jung et al. wrote:
“With the discovery of many pterosaur tracksites worldwide, there have been various attempts to find evidence for estimating possible trackmakers. The first approach for identifying the trackmaker is integrating the osteological data of pterosaurian body fossils with information preserved in trace fossils, and diverse variates can be considered for the suspected trackmaker.”

Peters 2011 catalog of pterosaur trackmakers was not cited. It only took a few minutes to identify a best match trackmaker using the catalog. This episode repeats S. Christopher Bennett’s curse, “You will not be published. And if you are published, you will not be cited.”

I wrote to Dr. Min Huh,
sending him a PDF that is traditionally missing from pterosaur track papers.

“Dear Dr. Min Huh:
I saw your preprint: Multi-Aged Small Pterosaur Track Assemblage from the Upper Cretaceous of Korea. A PDF not cited in your literature could have been useful: Peters 2011. A catalog of pterosaur pedes for trackmaker identification.  Ichnos 18(2): 114–141. See attached PDF.

I checked the catalog looking for a match to your tracks. Sinopterus dongi is the closest I was able to find. See attached. The location of the first interphalangeal joints seems to be the major difference. Otherwise the size and age are also good matches.

As you’ll see in the catalog (PDF) pterosaur tracks are like fingerprints. No two are exactly alike, contra traditional thinking.

Let me know your thoughts.”

Figure 1. Photos from Jung et al. 2021 preprint along with matching manus and pes from nearly coeval and nearby Sinopterus dongi.

From the Jung et al. introduction:
“Here, we report an assemblage of small pterosaur tracks, mainly consisting of manus tracks, from the Hwasun Seoyuri tracksite in the Upper Cretaceous Jangdong Formation of the Neungju Basin, Korea. This is the first evidence for the lineage of the small-size pterosaur was survived in the East Asia after the mid-Cretaceous period.”

“The Jangdong Formation which consists of silty mudstones and fine sandstones with pyroclastic materials from alluvial plain and sandflat. The age of the Jangdong Formation is inferred to be 94 Ma [Turonian] based on the U-Pb dating of zircons.”

Figure 2. Sinopterus, sister to the common ancestor of tapejarids and tupuxuarids.

Figure 3. Tapejara poling while floating, producing manus-only tracks, all to scale.

The preponderance of manus tracks in the Jangdong Formation
and the lack of directional terrestrial travel tracks suggests a shallow pond niche as shown here (Fig. 3) employing a somewhat related tapejarid form South America, rather than the Far East, poling while floating.

References
Jung J, Huh M, Hwang K-G, Kim H-J, Choi B-D and Xing L 2021. Multi-aged small pterosaur track assemblage from the Upper Cretaceous of Korea. Research Square. https://doi.org/10.21203/rs.3.rs-1136661/v1
Peters D 2011. A catalog of pterosaur pedes for trackmaker identification. Ichnos 18(2): 114–141.