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New Dissertation on Late Cretaceous Pterosaur Tracks of Korea
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Jerry Harris
May 1, 2025, 5:28:39 PMMay 1
to Dinosaur Mailing Group
Jung, J. 2025. Pterosaur tracks from the Hwasun Seoyuri tracksite (Late Cretaceous), Korea: Implications for paleoecological conditions and ichnotaxonomy in East Asia. Ph.D. dissertation, Chonnam National University, Korea, 265 pp.
Abstract: Pterosauria, an extinct clade of flying reptiles, first appeared in the Late Triassic and persisted until the end of the Cretaceous. Their wings were formed by a membrane extending from the elongated fourth digits of the manus to the ankle of the hindlimb, representing the earliest powered-flight vertebrates. Pterosaur ichnofossil offers critical insight into their ecology, ethology, and paleogeography, especially in regions where their body fossils are scarce. This dissertation aims to reveal information about pterosaur ecology and ichnotaxonomy using the pterosaur tracks in East Asia, mainly focusing on the tracks at the Hwasun Seoyuri tracksite and ichnotaxonomic.
The pterosaur ichnofossils in East Asia stratigraphically span from the Middle-Late Jurassic to the Late Cretaceous and only have been found in nonmarine sedimentary strata. Definitive pterosaur ichnofossils have been documented in East Asia, including Korea, China, and Japan. The coincidence of the pterodactyloid appearance in Asia and the geological age of the pterosaur tracksites supports the generation of most pterosaur tracks by pterodactyloids. This coincidence of pterodactyloid body fossils and pterosaur tracksites is also found in North America, Europe, and elsewhere.
The pterosaur footprint assemblage of about 350 manus-dominated tracks was found in the Jangdong Formation at the Hwasun Seoyuri tracksite, Neungju Basin in Korea. The tracks at this site exhibit unusual morphological characteristics that do not match the pedal morphology of any known Late Cretaceous pterosaurs. This footprint morphology suggests that the trackmakers may be a dsungaripteroid with 0.5 – 1.5 m wingspans. This footprint assemblage shows a normal distribution with a wide range of size variations. The Hwasun pterosaur footprints appear to display gregarious behavior by individuals of different ages, suggesting a possibility that the pterosaurs gathered in mixed-age groups.
New pterosaur tracks were found from an outcrop and multiple slabs in the Jangdong Formation at the Hwasun Seoyuri tracksite. The diverse lithology of the pterosaur track-bearing slabs indicates these slabs originated from multiple stratigraphic levels, and small pterosaurs occupied this area over an extended period, at least six stratigraphic levels. Unlike the known logarithmic growth patterns of pterosaurs, an unskewed normal distribution of footprint sizes suggests a predominantly immature population at this site. Moreover, the non-marine pterosaur tracksites in the mid-Cretaceous basins in the Korean Peninsula may reflect habitat ecological shifts from coastal to terrestrial during this period. This is supported by the ontogenic characteristics of individuals seen in many pterosaur body fossil assemblages from China and Brazil.
Two-dimensional landmark-based Geometric Morphometric Analysis (GMA) were employed to investigate the manus tracks of four ichnotaxa of Pteraichnus from Early Cretaceous East Asia. The GMA results not only reveal the morphological characters not distinguished in traditional measurement but also provide new insight into ichnotaxonomic classification, particularly for invalid or questionable ichnotaxa, and allow us to evaluate the ichnotaxonomic validity of manus-only tracks. This approach highlights the potential for spatiotemporal comparisons between disparate pterosaur footprints. The distinct morphological features observed in tracks from relatively close localities suggest the presence of diverse pterosaur faunas across East Asia. Further research with an expanded dataset of pterosaurian ichnotaxa is recommended to refine ichnotaxonomic classifications and enhance our knowledge of pterosaur paleogeography.
The pterosaur ichnofossils in East Asia stratigraphically span from the Middle-Late Jurassic to the Late Cretaceous and only have been found in nonmarine sedimentary strata. Definitive pterosaur ichnofossils have been documented in East Asia, including Korea, China, and Japan. The coincidence of the pterodactyloid appearance in Asia and the geological age of the pterosaur tracksites supports the generation of most pterosaur tracks by pterodactyloids. This coincidence of pterodactyloid body fossils and pterosaur tracksites is also found in North America, Europe, and elsewhere.
The pterosaur footprint assemblage of about 350 manus-dominated tracks was found in the Jangdong Formation at the Hwasun Seoyuri tracksite, Neungju Basin in Korea. The tracks at this site exhibit unusual morphological characteristics that do not match the pedal morphology of any known Late Cretaceous pterosaurs. This footprint morphology suggests that the trackmakers may be a dsungaripteroid with 0.5 – 1.5 m wingspans. This footprint assemblage shows a normal distribution with a wide range of size variations. The Hwasun pterosaur footprints appear to display gregarious behavior by individuals of different ages, suggesting a possibility that the pterosaurs gathered in mixed-age groups.
New pterosaur tracks were found from an outcrop and multiple slabs in the Jangdong Formation at the Hwasun Seoyuri tracksite. The diverse lithology of the pterosaur track-bearing slabs indicates these slabs originated from multiple stratigraphic levels, and small pterosaurs occupied this area over an extended period, at least six stratigraphic levels. Unlike the known logarithmic growth patterns of pterosaurs, an unskewed normal distribution of footprint sizes suggests a predominantly immature population at this site. Moreover, the non-marine pterosaur tracksites in the mid-Cretaceous basins in the Korean Peninsula may reflect habitat ecological shifts from coastal to terrestrial during this period. This is supported by the ontogenic characteristics of individuals seen in many pterosaur body fossil assemblages from China and Brazil.
Two-dimensional landmark-based Geometric Morphometric Analysis (GMA) were employed to investigate the manus tracks of four ichnotaxa of Pteraichnus from Early Cretaceous East Asia. The GMA results not only reveal the morphological characters not distinguished in traditional measurement but also provide new insight into ichnotaxonomic classification, particularly for invalid or questionable ichnotaxa, and allow us to evaluate the ichnotaxonomic validity of manus-only tracks. This approach highlights the potential for spatiotemporal comparisons between disparate pterosaur footprints. The distinct morphological features observed in tracks from relatively close localities suggest the presence of diverse pterosaur faunas across East Asia. Further research with an expanded dataset of pterosaurian ichnotaxa is recommended to refine ichnotaxonomic classifications and enhance our knowledge of pterosaur paleogeography.
Through various analyses, including quantitative analysis of pterosaur footprint fossils, this dissertation identified new insight into ecological conditions and ichnotaxonomy, such as group structures, age distributions, habitat preferences, and morphological differentiation of ichnofossils. By utilizing diverse research methodologies to a large dataset, both previously reported and newly discovered, it overcomes traditional limitations, providing a more comprehensive understanding of pterosaur ecology. This approach is expected to integrate ichnofossil and body fossil data, offering a holistic perspective on pterosaurs.
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