Ben Creisler
New papers:
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David I. Whiteside & Christopher J. Duffin (2020)
New haramiyidan and reptile fossils from a Rhaetian bedded sequence close to the famous 'Microlestes' Quarry of Holwell, UK.
Proceedings of the Geologists' Association (advance online publication)
https://doi.org/10.1016/j.pgeola.2020.09.003https://www.sciencedirect.com/science/article/abs/pii/S0016787820300912We describe here new Late Triassic haramiyidan mammaliaform and reptile fossils from near the classic 'Microlestes' Quarry at Holwell, Somerset, U.K., where Charles Moore discovered a huge collection of microvertebrates in the 1850s. Mooreâs discoveries included the haramiyid Thomasia (formerly 'Microlestes' and Microcleptes) for which he achieved worldwide fame. Subsequently, despite much fossicking by researchers at Holwell, few new identifiable specimens of mammaliamorphs and lepidosaurs have been recorded and these were by KÃhne in 1939. The new finds described here from a bedded sequence, not from a fissure, add significantly to our knowledge of the Holwell tetrapods and to the Rhaetian terrestrial faunas of the SW U.K. Our discovery of haramiyidan teeth includes a previously unknown type of Theroteinus, a genus not previously recorded from outside of the St-Nicholas-de-Port locality in France. An archosaur tooth, possibly from a phytosaur, is also recorded. The new lepidosaur specimens add significant detail to the recently described 'basal' rhynchocephalian Penegephyrosaurus curtiscoppi as well as demonstrating that the global diversity of Lepidosauria in the Late Triassic remains incompletely known.
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He Wang, Sha Li, Bo Wang, Edmund A. Jarzembowski, Chong Dong, Fang Yanan, Xiao Teng, Tingting Yu, Lichao Yang, Yuling Li, Xiangdong Zhao, Naihua Xue, Su-Chin Chang & Haichun Zhang (2020)
Synthesis of a chrono- and biostratigraphical framework for the Lower Cretaceous of Jiuquan, NW China: Implications for major evolutionary events.
Earth-Science Reviews 103474
https://doi.org/10.1016/j.earscirev.2020.103474 Highlights
We establish the stratigraphy and time scales for the Lower Cretaceous in Jiuquan.
We review how a Cretaceous inland ecosystem responded to global climatic change.
This study summarizes the detailed fossil records for the Jehol Biota in NW China.
Robust age for the less-studied outcrops allows to test the Jehol radiations.
A close link existed between early Ornithuromorpha evolution and OAE1a.
Abstract
With a depositional history spanning the early Aptian to early Albian (~19 mys), the Lower Cretaceous Xinminpu Group in Jiuquan, NW China provides detailed record of an inland ecosystem responding to global climatic and environmental changes. The Xinminpu Group exhibits the most typical elements of the Jehol Biota found outside NE China, a highly diverse avifauna and a mid-Cretaceous angiosperm flora. The absence of a comprehensive stratigraphical framework for this area however limits the degree to which the unit can be interpreted relative to coeval sections and the geological records in genera. Recent fossil discoveries and radio-isotopic age data can provide a more detailed biostratigraphical and chronostratigraphical framework for Lower Cretaceous units around Jiuquan. The data complied here indicate that the Chijinpu Formation correlates with the middle-upper Yixian and lower Jiufotang formations of NE China making it early Aptian in age, and the Xiagou Formation correlates with the upper Jiufotang and Shahai formations making it late early Aptian-early Albian in age. This research further reports a novel zircon U-Pb age constraint of 112.4 Â 0.3 Ma for a basalt sample from the lowermost Zhonggou Formation, which is supported to be correlated with the Fuxin Formation of early Albian age. The Chijinpu Formation contains typical elements of the Jehol Biota, i.e. the Eosestheria-Lycoptera-Ephemeropsis trisetalis assemblage, confirming the interpretation that the Jehol Biota had reached Jiuquan during its second evolutionary stage. The Xiagou Formation contains the amphibious avifauna appearing just above OAE1a, indicating a close link between the early Ornithuromorpha evolution and early Aptian global climate changes. The Zhonggou Formation in Jiuquan records the first appearance of an angiosperm flora above OAE1b. Depositional indicators suggest a humid climate with a gradual shift to arid conditions during this time. This review paper laid foundation for the systematic study of the well-preserved Early Cretaceous ecosystem in Jiuquan, allowing to understand correlations between inland and marine environments as recorded in sediments from this critical period.