Jiufotang formation
The Jiufotang Formation ( Chinese 九 佛堂 组 , Pinyin Jiǔfótáng zǔ , "Hall of the Nine Buddhas") is a geological formation from the Lower Cretaceous Liaoning in the northeast of the People's Republic of China . It is from it that feathered dinosaurs , primitive birds , pterosaurs and other organisms come from. Together with the stratigraphically older Yixian formation , it belongs to the Jehol group .
Age
Their exact age has long been disputed, estimates ranged from the Malm to the Lower Cretaceous . He et al. (2004) radiometrically determined an age of 120.3 ± 0.7 Ma BP for an activated tuff horizon using the argon isotopes . This corresponds to the Aptium , a stage of the Lower Cretaceous . Zhou et al. (2003) found an age of 110.6 Ma BP, ie lower albium , for a basaltic storage corridor in the uppermost section of the Jiufotang Formation . The entire formation should therefore cover the period from the Upper Aptian to the Lower Albian .
stratigraphy
The Jiufotang Formation overlays the Yixian Formation . Their thickness varies between 800 and 1200 meters. It begins coarse siliciclastic with conglomerate and sandstone and then turns into finer tufa claystone . This is followed by a three-fold alternation of tufa sandstone and finer tufa claystone.
Fossil content
The fossils of the Jiufotang Formation can be divided into three larger fauna areas:
- Fish from the Lycoptera - Ichthyofauna with the species Jinanichthys longicephalus , Lycoptera davidi , Lycoptera muroii , Peipiaosteus pani , Protopsephurus liui and Sinamia zdanskyi .
- Dinosaurs of the Psittacosaurus fauna , such as the ornithic Psittacosaurus meileyingensis and Psittacosaurus mongoliensis . Sauropods are represented by an unnamed titanosaur . Feathered theropods of the formation include Microraptor gui , Microraptor zhaoianus and Similicaudipteryx yixianensis .
- Birds of Cathayornis - Chaoyangia avifauna as boluochia zhengi , Changzuiornis ahgmi , Chaoyangia beishanensis , Chiappeavis magnapremaxillo , Confuciusornis sanctus , Cuspirostrisornis Houi , jeholornis prima , Jianchangornis microdonta , Jixiangornis orientalis , Largirostrornis sexdentoris , Longchengornis sanyanensis , longipteryx chaoyangensis , Longusunguis kurochkini , Parabohaiornis martini , Parapengornis eurycaudatus , Sapeornis chaoyangensis , Sinornis santensis (inc. Cathayornis yandica ), Songlingornis linghensis , Yanornis martini and Yixianornis grabaui .
In 2011 the mammal Liaoconodon was described from the formation, which shows a transition stage between the primary and secondary TMJ .
literature
- HY He, XL Wang, ZH Zhou, F. Wang, A. Boven, GH Shi, RX Zhu: Timing of the Jiufotang Formation (Jehol Group) in Liaoning, northeastern China, and its implications. In: Geophysical Research Letters Vol. 31, 2004, No. 13, ISSN 0094-8276 , p. 1709.
- Zonghe Zhou, Paul M. Barrett, Jason Hilton: An exceptionally preserved Lower Cretaceous ecosystem . In: Nature 421, February 20, 2003, ISSN 0028-0836 , pp. 807-814.
Individual proof
- ↑ Jin Meng, Yuanqing Wang & Chuankui Li: Transitional mammalian middle ear from a new Cretaceous Jehol eutriconodont. Nature 472, 181-185 doi : 10.1038 / nature09921