Isolated theropod pedal phalanges identification with elliptic Fourier analysis + vertebrate footprints from Mesozoic of Thailand (free pdfs)
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Ben Creisler
May 1, 2026, 1:11:06 AM (3 days ago) May 1
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Ben Creisler
Trystan M. Warnock-Juteau, Stephanie M. Smith & Thomas M. Cullen (2026)
Elliptic Fourier analysis as a tool for the taxonomic identification of isolated theropod pedal phalanges
The Anatomical Records (advance online publication)
doi: https://doi.org/10.1002/ar.70210
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.70210
Free pdf:
https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.70210
Studies of Upper Cretaceous deposits in North America have provided invaluable insights into the continental ecosystems of this time. Theropod (Saurischia, Dinosauria) pedal phalanges are commonplace in these deposits but can be difficult to identify at a finer taxonomic resolution. This, in part, results from a lack of data regarding the individual, ontogenetic, and intraspecific variation that exists among theropod pedal phalanges, and potential differences in phalanx shape that distinguish individual families and species. In this study, we use elliptic Fourier analysis to quantify pedal phalanx shape in a sample of individuals of known species from multiple theropod families in multiple views. The resulting variables were analyzed using principal component analysis to identify patterns of (dis)similarity among different theropod taxa and between phalanx positions and, as such, provide insights into the phalanx shape variation that existed among North American theropods during the Late Cretaceous. This study finds that caenagnathids often possess more gracile pedal phalanges relative to other theropod taxa, particularly when viewed dorsally or ventrally (e.g., for digits II, III, and IV). Although tyrannosaurid and ornithomimid pedal phalanges are generally similar to one another, even in similarly sized individuals the former are found to be more robust in shape than the latter for certain phalanges (e.g., II-1, III-2, and III-3) in dorsal and ventral views. In some instances, the shape of the lateral, medial, and distal margins of tyrannosaurid pedal phalanges differ considerably from those of ornithomimids (e.g., IV-1 in dorsal/ventral view; II-1, III-4, IV-5 in lateral/medial view). The use of elliptic Fourier analysis here provides quantitative data on the variation present among Late Cretaceous theropod pedal phalanges and provides evidence that theropod taxa can be identified down to the family level based on pedal phalanx morphology. This greatly increases the potential utility of isolated theropod phalanges in biodiversity assessments of Cretaceous fossil assemblages, particularly those with a lack of well-preserved skeletal samples.
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New papers:
Free pdf:
Trystan M. Warnock-Juteau, Stephanie M. Smith & Thomas M. Cullen (2026)
Elliptic Fourier analysis as a tool for the taxonomic identification of isolated theropod pedal phalanges
The Anatomical Records (advance online publication)
doi: https://doi.org/10.1002/ar.70210
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.70210
Free pdf:
https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.70210
Studies of Upper Cretaceous deposits in North America have provided invaluable insights into the continental ecosystems of this time. Theropod (Saurischia, Dinosauria) pedal phalanges are commonplace in these deposits but can be difficult to identify at a finer taxonomic resolution. This, in part, results from a lack of data regarding the individual, ontogenetic, and intraspecific variation that exists among theropod pedal phalanges, and potential differences in phalanx shape that distinguish individual families and species. In this study, we use elliptic Fourier analysis to quantify pedal phalanx shape in a sample of individuals of known species from multiple theropod families in multiple views. The resulting variables were analyzed using principal component analysis to identify patterns of (dis)similarity among different theropod taxa and between phalanx positions and, as such, provide insights into the phalanx shape variation that existed among North American theropods during the Late Cretaceous. This study finds that caenagnathids often possess more gracile pedal phalanges relative to other theropod taxa, particularly when viewed dorsally or ventrally (e.g., for digits II, III, and IV). Although tyrannosaurid and ornithomimid pedal phalanges are generally similar to one another, even in similarly sized individuals the former are found to be more robust in shape than the latter for certain phalanges (e.g., II-1, III-2, and III-3) in dorsal and ventral views. In some instances, the shape of the lateral, medial, and distal margins of tyrannosaurid pedal phalanges differ considerably from those of ornithomimids (e.g., IV-1 in dorsal/ventral view; II-1, III-4, IV-5 in lateral/medial view). The use of elliptic Fourier analysis here provides quantitative data on the variation present among Late Cretaceous theropod pedal phalanges and provides evidence that theropod taxa can be identified down to the family level based on pedal phalanx morphology. This greatly increases the potential utility of isolated theropod phalanges in biodiversity assessments of Cretaceous fossil assemblages, particularly those with a lack of well-preserved skeletal samples.
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Free pdf:
Tida Liard, Romain Liard and Eric Buffetaut (2026)
A Review of Vertebrate Footprints from the Mesozoic of Thailand and Their Palaeobiogeographical Significance
Fossil Studies 4(2): 10
doi: https://doi.org/10.3390/fossils4020010
https://www.mdpi.com/2813-6284/4/2/10
Thailand preserves one of the most extensive records of Mesozoic vertebrate tracks in Tropical Asia, yet these ichnological data have never been comprehensively synthesized. This review compiles and reassesses all known Triassic to Cretaceous vertebrate tracksites in Thailand to clarify their stratigraphic distribution, taxonomic diversity, and palaeobiogeographical significance. Published records, new field observations, and updated stratigraphic correlations are integrated to evaluate trackmaker attributions and temporal patterns. The Thai record documents diverse assemblages including chirotheriids, early theropods, sauropodomorphs, ornithopods, sauropods, and crocodilians. Late Triassic–Early Jurassic assemblages capture a major faunal transition, revealing the co-occurrence of non-dinosaurian archosaurs and some of the earliest dinosaurs in the region, whereas Lower Cretaceous sites are dominated by theropods, sauropods and diverse ornithopods. Comparison with other Asian ichnofaunas indicates faunal continuity across eastern Asia and supports early dinosaur dispersal into equatorial low latitudes. This synthesis also evaluates site conservation, highlighting the vulnerability of several Triassic localities and a positive trend of community-led discoveries since 2009, underscoring the need for proactive management and standardized digital documentation. Overall, the Thai ichnological succession represents the most complete Mesozoic track record presently known from Tropical Asia and provides key insights into vertebrate evolution, palaeoecology, and regional biogeography.
===
Tida Liard, Romain Liard and Eric Buffetaut (2026)
A Review of Vertebrate Footprints from the Mesozoic of Thailand and Their Palaeobiogeographical Significance
Fossil Studies 4(2): 10
doi: https://doi.org/10.3390/fossils4020010
https://www.mdpi.com/2813-6284/4/2/10
Thailand preserves one of the most extensive records of Mesozoic vertebrate tracks in Tropical Asia, yet these ichnological data have never been comprehensively synthesized. This review compiles and reassesses all known Triassic to Cretaceous vertebrate tracksites in Thailand to clarify their stratigraphic distribution, taxonomic diversity, and palaeobiogeographical significance. Published records, new field observations, and updated stratigraphic correlations are integrated to evaluate trackmaker attributions and temporal patterns. The Thai record documents diverse assemblages including chirotheriids, early theropods, sauropodomorphs, ornithopods, sauropods, and crocodilians. Late Triassic–Early Jurassic assemblages capture a major faunal transition, revealing the co-occurrence of non-dinosaurian archosaurs and some of the earliest dinosaurs in the region, whereas Lower Cretaceous sites are dominated by theropods, sauropods and diverse ornithopods. Comparison with other Asian ichnofaunas indicates faunal continuity across eastern Asia and supports early dinosaur dispersal into equatorial low latitudes. This synthesis also evaluates site conservation, highlighting the vulnerability of several Triassic localities and a positive trend of community-led discoveries since 2009, underscoring the need for proactive management and standardized digital documentation. Overall, the Thai ichnological succession represents the most complete Mesozoic track record presently known from Tropical Asia and provides key insights into vertebrate evolution, palaeoecology, and regional biogeography.
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