Tida Liard, Romain Liard & Krishna Sutcha (2019)
Dinosaur footprints from the Sao Khua Formation (Early Cretaceous) of Phu Kao National Park, Northeast Thailand.
Annales de PalÃontologie (advance online publication)
doi:
https://doi.org/10.1016/j.annpal.2019.07.001https://www.sciencedirect.com/science/article/abs/pii/S0753396919300412The first documented dinosaur footprints from Southeast Asia were theropod footprints found in Thailand at Phu Luang Wildlife Sanctuary. Since then, Mesozoic vertebrate footprints have been discovered in twelve different localities in Thailand. In 2000, dinosaur footprints were found in Phu Kao National Park in Northeastern Thailand, however, they have never been studied in detail. The following study presents the first map, the complete measurements, the geology, and stratigraphy of the site and surrounding area. The study discusses the nature of the trackmaker and the digitigrade character of the footprints. This discovery represents the first documented occurrence of dinosaur footprints inside the Early Cretaceous Sao Khua Formation from Thailand.
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Victoria Arbour, David C Evans , D. Jade Simon, Thomas Cullen & Dennis R. Braman (2019)
Cretaceous flora and fauna of the Sustut Group near the Sustut River, northern British Columbia, Canada.
Canadian Journal of Earth Sciences (advance online publication)
doi:
https://doi.org/10.1139/cjes-2019-0031https://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2019-0031#.XaiJOJJKjX4A partial ornithischian dinosaur skeleton discovered near the Sustut River in 1971 has, to date, represented the only vertebrate fossil remains recovered from the Sustut Basin in northern British Columbia, Canada, but the geological provenance and age of this specimen has remained unclear. We provide new data on the age of this dinosaur specimen based on reconnaissance palaeontological prospecting along the Sustut River, and also report new vertebrate and plant fossils from this region. A skeletal fragment of the turtle Basilemys sp. was discovered at a site closely matching field notes describing the initial collection of the ornithischian dinosaur, suggesting that the new turtle fossil derives from the same locality as the dinosaur. Palynomorphs collected from this site include the marker taxon Pseudoaquilapollenites bertillonites, found in the lower Hell Creek Formation, and suggesting an age range of between 68.2 and 67.2 Ma for the locality. To the west of this locality we discovered multiple new fossil plant sites preserving wood and the leaves of Metasequoia and several angiosperms, and one site preserved fronds resembling the tree fern Coniopteris sp., suggesting a Cenomanian or older age for sites the area. The complex translational history of the Intermontane Terrane means that the newly discovered turtle may not represent a northern range extension for Basilemys, but it does represent one of the westernmost occurrences of this genus. The discovery of new vertebrate fossil remains in a region with relatively little accessible outcrop at present indicates for the potential for future discoveries in the higher elevation outcrops of the Sustut Basin in this mountainous region of British Columbia.
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Dennis V. Kent, Paul E. Olsen, Christopher Lepre, Cornelia Rasmussen, Roland Mundil, George E. Gehrels, Dominique Giesler, Randall B. Irmis, John W. Geissman Â& William G. Parker (2019)
Magnetochronology of the entire Chinle Formation (Norian age) in a scientific drill core from Petrified Forest National Park (Arizona, USA) and implications for regional and global correlations in the Late Triassic.
Geochemistry, Geophysics, Geosystems (advanced online publication)
doi:
https://doi.org/10.1029/2019GC008474https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GC008474
Building on an earlier study that confirmed the stability of the 405âkyr eccentricity climate cycle and the timing of the NewarkâHartford astrochronostratigraphic polarity time scale (NâH APTS) back to 215 Ma, we extend the magnetochronology of the Late Triassic Chinle Formation to its basal unconformity in scientific drill core PFNPâ1A from Petrified Forest National Park (Arizona, USA). The 335âmâthick Chinle section is imprinted with paleomagnetic polarity zones PF1r to PF10n, which we correlate to chrons E17r to E9n (~209 to 224 Ma) of the NâH APTS. A sediment accumulation rate of ~34 m/Myr can be extended down to ~270 meters, close to the base of the Sonsela Member and the base of magnetozone PF5n, which we correlate to chron E14n that onsets at 216.16 Ma. Magnetozones PF5r to PF10n in the underlying 65âmâthick section of the mudstoneâdominated Blue Mesa and Mesa Redondo members plausibly correlate to chrons E13r to E9n, indicating a sediment accumulation rate of only ~10 m/Myr. Published high precision UâPb detrital zircon dates from the lower Chinle tend to be several million years older than the magnetochronological age model. The source of this discrepancy is unclear but may be due to sporadic introduction of juvenile zircons that get recycled. The new magnetochronological constraint on the base of the Sonsela Member brings the apparent timing of the included AdamanianâRevueltian land vertebrate faunal zone boundary and the Zone II to Zone III palynofloral transition closer to the temporal range of the ~215 Ma Manicouagan impact structure in Canada.
Key Points
Chinle Formation as recovered extends from ~224 Ma to 209 Ma (chrons E9n to E17r).
Base of Sonsela Member at ~216 Ma (chron E14n) places older age limit on AdamanianâRevueltian faunal transition.
Published high precision UâPb detrital zircon ages from the lower Sonsela and Blue Mesa Members tend to be anomalously old by comparison.
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Coprolites are traditionally analyzed from a morphological perspective. Few studies exist from an organic geochemical perspective, and most of these consider recent specimens. This study represents an analysis of coprolites from deep time, using both traditional one-dimensional and also two-dimensional gas chromatography-mass spectrometry. We find organic molecules preserved in coprolites from the Triassic, and that both dietary habits of the defecators and paleoenvironment can be interpreted using comparative distributions of biomarker abundances in the coprolites. Steranes having 27 carbon atoms are known to be derived from animal steroids whereas those with 29 carbon atoms are known to be derived from plant steroids. The predominance of steranes with 27 carbon atoms over those with 29 carbon atoms in a non-marine environment was interpreted as evidence for the defecator(s) being predominantly carnivorous or possibly omnivorous. A series of tricyclic terpanes ranging from C19 to C28 was examined to determine the environment. The present study suggests that one or possibly all of the defecators may have been small-medium carnivores that lived in an aquatic or near aquatic setting.
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