The structure and orientation of the posterior extremity （tail club） of the caudal vertebrae of Mamenchisaurus hochuanensis Young and Chao, 1972 from the Upper Jurassic Shangshaximiao Formation has been analyzed to ...The structure and orientation of the posterior extremity （tail club） of the caudal vertebrae of Mamenchisaurus hochuanensis Young and Chao, 1972 from the Upper Jurassic Shangshaximiao Formation has been analyzed to determine the tail club function using Finite Element Analysis. Of the four caudal vertebrae composing the tail club, the second largest （C＂1＂） was probably the most proximal, and is fixed with the preceding sequence of the caudal vertebrae, whereas the smallest （C＂4＂） is free and forms the termination of the tail club. Our analysis also suggests that the tail club is more efficient in lateral swinging rather than up-and-down motion, and that the best region for the tail club to impact is at the spine of the largest of the four caudals （C＂2＂）, with a maximum load for impact at about 450 N. The tail club of Mamenchisaurus hochuanensis probably also had limitations as a defense weapon and was more possibly a sensory organ to improve nerve conduction velocity to enhance the capacity for sensory perception of its surroundings.展开更多
Ceratodus is a form genus of ceratodontid lungfishes.Until now,only 14 specimens have been reported from the Mesozoic of China.Detailed measurements and characteristic comparisons based on 15 well-preserved lungfish t...Ceratodus is a form genus of ceratodontid lungfishes.Until now,only 14 specimens have been reported from the Mesozoic of China.Detailed measurements and characteristic comparisons based on 15 well-preserved lungfish tooth plates of Ceratodus type,uncovered from the upper member of the Upper Jurassic Shaximiao Formation at Luojiashan,Qianfeng District,Guang'an,Sichuan Province in 2019,allow us to establish a new species,Ceratodus guanganensis sp.nov.,on the basis of its small swollen irregular triangular tooth plate with four low and swollen radial crests on the occlusal surface without denticles.Other specimens from the same locality can be referred to C.szechuanensis and C.youngi.This is the first discovery of Ceratodus in the Guang'an region and represents the fifth Ceratodus fossil site in the Sichuan Basin.The discovery indicates that the climate was hot and arid in the Sichuan Basin during the Late Jurassic,and reveals a tectonic paleogeographic relationship between the Yangtze block in southwestern China and the Kola Basin in northern Thailand.展开更多
基金supported by the Chinese Ministry of Science and Technology (973 Project,2006CB701405)China Geological Survey+2 种基金National Natural Science Foundation of ChinaAccurate Reconstruction of Dinosaurs (Zigong Dinosaur Museum Project,20071201)the Palaeobiology Program of Chinese National Geography International (CNGi)
文摘The structure and orientation of the posterior extremity （tail club） of the caudal vertebrae of Mamenchisaurus hochuanensis Young and Chao, 1972 from the Upper Jurassic Shangshaximiao Formation has been analyzed to determine the tail club function using Finite Element Analysis. Of the four caudal vertebrae composing the tail club, the second largest （C＂1＂） was probably the most proximal, and is fixed with the preceding sequence of the caudal vertebrae, whereas the smallest （C＂4＂） is free and forms the termination of the tail club. Our analysis also suggests that the tail club is more efficient in lateral swinging rather than up-and-down motion, and that the best region for the tail club to impact is at the spine of the largest of the four caudals （C＂2＂）, with a maximum load for impact at about 450 N. The tail club of Mamenchisaurus hochuanensis probably also had limitations as a defense weapon and was more possibly a sensory organ to improve nerve conduction velocity to enhance the capacity for sensory perception of its surroundings.
基金supported by the Accurate Reconstruction of Dinosaurs (Zigong Dinosaur Museum Project, 20071201)Chinese Ministry of Science and Technology (973 Project, 2006CB701405)+1 种基金China Geological Survey, National Geological Specimen Collection Outline of the Ministry of Land and Resources P.R.C(No. 1210811302)Palaeobiology Program of Chinese National Geography International (CNGi)
基金This work has been funded by the Land and Resources survey project(Grant No.DD20221690 and DD20190524).
文摘Ceratodus is a form genus of ceratodontid lungfishes.Until now,only 14 specimens have been reported from the Mesozoic of China.Detailed measurements and characteristic comparisons based on 15 well-preserved lungfish tooth plates of Ceratodus type,uncovered from the upper member of the Upper Jurassic Shaximiao Formation at Luojiashan,Qianfeng District,Guang'an,Sichuan Province in 2019,allow us to establish a new species,Ceratodus guanganensis sp.nov.,on the basis of its small swollen irregular triangular tooth plate with four low and swollen radial crests on the occlusal surface without denticles.Other specimens from the same locality can be referred to C.szechuanensis and C.youngi.This is the first discovery of Ceratodus in the Guang'an region and represents the fifth Ceratodus fossil site in the Sichuan Basin.The discovery indicates that the climate was hot and arid in the Sichuan Basin during the Late Jurassic,and reveals a tectonic paleogeographic relationship between the Yangtze block in southwestern China and the Kola Basin in northern Thailand.
