Bone guy Posted July 19, 2018 Share Posted July 19, 2018 I'm very confused by the Yixian formation, it seems that I can never get a straight answer as to the age of the formation. 99.99999% of sellers who sell Yixian formation fossils claim the age is early Cretaceous, but some published papers say other wise. Example: recently I purchased a Protosephurus liui which is from the Yixian. The seller claimed the age of the fish is early Cretaceous. However, a paper I read about Protosephurus liui pointed toward the fish being late Jurassic. Maybe the Yixian just crosses over both the late Jurassic and early Cretaceous....and both time periods are applicable? Link to comment Share on other sites More sharing options...
Troodon Posted July 19, 2018 Share Posted July 19, 2018 Yixian formation is early Cretaceous (Barremian - Aptian) Once thought to be late jurassic to early cretaceous this 1999 paper used radiometric dating to resolve the dates. "The results of this dating study indicate that the lower Yixian fossil horizons are not Jurassic but rather are at least 20Myr younger, placing them within middle Early Cretaceous time" https://www.researchgate.net/publication/32023885_Swisher_C_C_Wang_Y-Q_Wang_X-L_Xu_X_Wang_Y_Cretaceous_age_for_the_feathered_dinosaurs_of_Liaoning_China_Nature_400_58-61 In a late 2017 paper some changes were made " The widely accepted stratigraphic column for the Yixian Formation requires reinterpretation" its paywalled so not sure if the reinterpretation is minor or major but its still early Cretaceous and not jurassic https://www.researchgate.net/publication/32023885_Swisher_C_C_Wang_Y-Q_Wang_X-L_Xu_X_Wang_Y_Cretaceous_age_for_the_feathered_dinosaurs_of_Liaoning_China_Nature_400_58-61 4 Link to comment Share on other sites More sharing options...
Bone guy Posted July 20, 2018 Author Share Posted July 20, 2018 Perfect! My mystery is solved Link to comment Share on other sites More sharing options...
caldigger Posted July 20, 2018 Share Posted July 20, 2018 2 hours ago, Bone guy said: Perfect! My mystery is solved Great, can we all go out for pizza now? 1 Link to comment Share on other sites More sharing options...
doushantuo Posted July 20, 2018 Share Posted July 20, 2018 The 2017 Pal/Pal/Pal paper uses Renne's recalibrated Fish Canyon sanidine potassium decay standard, with concomitant result: some new plateau ages The Lower Lava unit (straddling the boundary between the Luijatun and Jianshangou Formations) is now 0,70 Ma older 1 Link to comment Share on other sites More sharing options...
Fossildude19 Posted July 20, 2018 Share Posted July 20, 2018 9 hours ago, doushantuo said: The 2017 Pal/Pal/Pal paper uses Renne's recalibrated Fish Canyon sanidine potassium decay standard,with concomitant result: some new plateau ages The Lower Lava unit(straddling the boundary between the Luijatun and Jianshangou Formations) is now 0,70 Ma older Author citation? And can you explain for those of us not in the know, how this relates to the question? I honestly have no idea what this is about, or how it relates. 1 Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
piranha Posted July 20, 2018 Share Posted July 20, 2018 Luckily, we received a clue: Pal/Pal/Pal (=Palaeogeography, Palaeoclimatology, Palaeoecology) An advanced search for all 2017 papers containing the keyword 'sanidine' revealed this paper: Chang, S.C., Gao, K.Q., Zhou, C.F., & Jourdan, F. 2017 New chronostratigraphic constraints on the Yixian Formation with implications for the Jehol Biota. Palaeogeography, Palaeoclimatology, Palaeoecology, 487:399-406 "Fair Use" and courtesy to the authors and future participants of TFF, dictates this info should always be provided when attaching any figures, images or text from copyrighted material. 3 Link to comment Share on other sites More sharing options...
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