The Middle Triassic Panxian fauna is a physical marker and representative record of the rapid recovery of the Triassic marine ecosystem following the Early Triassic stagnant stage after the end-Permian mass extinction...The Middle Triassic Panxian fauna is a physical marker and representative record of the rapid recovery of the Triassic marine ecosystem following the Early Triassic stagnant stage after the end-Permian mass extinction. Ten marine reptile taxa have been found from the 1.82-2.10 m-thick fossiliferous level in the Upper Member of the Guanling Formation, which can be subdivided into three marine reptile beds through the analysis on the stratigraphic distributions of fossil reptiles. The Lower Reptile Bed yields the sauropterygians Placodus inexpectatus Jiang et al., 2008 and Lariosaurus hongguoensis Jiang et al., 2006, the ichthyopterygians Xinminosaurus catactes Jiang et al., 2008 and Phalarodon cf. Phalarodon fraasi Merriam, 1910, associated with Mixosaurus panxianensis Jiang et al., 2006, representing a stage of predominance of durophagous taxa. In this bed, the large complete skeletons may reach up to 2.3 m in length, and lithofacies and chemostratigraphic analyses indicate a relatively deep carbonate platform with an oxic water environment near the bottom, as well as a rising sea level The Middle Reptile Bed yields the sauropterygian Nothosaurus yangjuanensis Jiang et al., 2006 and the archosaur Qianosuchus mixtus Li et al., 2006, associated with Mixosaurus panxianensis Jiang et al., 2006. The fossils in this bed are characterized by its pincering dentition and large overall body size, with the largest possibly exceeding 3 m in length. This bed might represent a time of deepest basin with relatively anoxic condition near the bottom. The Upper Reptile Bed yields the sauropterygians Wumengosaurus delicatomandibularis Jiang et al., 2008, Keichousaurus sp., the protorosaur Dinocephalosaurus orientalis Li, 2003, and the ichthyopterygian Mixosaurus panxianensis Jiang et al., 2006. In this bed, reptilian taxa characterized by suction feeding appeared, and most are less than 1 m long. This bed corresponds to a period of decreasing water depth.展开更多
Two complete specimens from the Pelsonian （Middle Anisian, Middle Triassic） of Luoping, Yunnan Province, South China are referred to a new actinopterygian genus, Luopingichthys gen. nov., and ascribed to the perleid...Two complete specimens from the Pelsonian （Middle Anisian, Middle Triassic） of Luoping, Yunnan Province, South China are referred to a new actinopterygian genus, Luopingichthys gen. nov., and ascribed to the perleidiform family Polzbergidae based especially on a typical synapomorphy of a peculiar premaxillary-maxillary complex, i.e., the fusion between premaxillary and maxillary along the antero-dorsal margin of the maxillary. The new taxon differs from other deep-bodied representatives of the family, Felberia and Stoppania, in its fusiform or deep fusiform body shape; sickle-shaped preopercular with short infraorbital process; lack of modified scales at the base of the anal fin; the short-based dorsal fin; scarcely ornamented scales; and thin anterior teeth. Based on a redescription of the holotype of the taxon Ctenognathichthys hattichi from the Middle Triassic （Ladinian） Prosanto Formation, Canton Graubiinden, eastern Switzerland, the only known specimen, which shows the same fusion between premaxillary and maxillary, the systematic position of the species is clarified and the taxon is proposed to be a further representative of the family Polzbergidae, and is transferred to the new genus.展开更多
Saurichthys dawaziensis sp. nov., from the third member of the Gejiu Formation （Anisian of Middle Triassic） in the vicinity of Luoping, Yunnan Province, is a small to mediumsized saurichthyid fish. It is characteriz...Saurichthys dawaziensis sp. nov., from the third member of the Gejiu Formation （Anisian of Middle Triassic） in the vicinity of Luoping, Yunnan Province, is a small to mediumsized saurichthyid fish. It is characterized by the efferent pseudobranchial arteries penetrating on the parasphenoid and the mandible sensory canal with a branch in the angular. The new species is more derived than the Lower Triassic species in having a relatively narrow postorbital region, short preopercular, single ossification of the sclerotic ring, small haemal arches between the pelvic fins and the anal fin without ossified spines, and in the absence of quadratojugal. It is more primitive than the Middle and Upper Triassic Saurichthys in having fringing fulcra and numerous segments in the unpaired fins, and the presence of both prae- and post-zygapophyses in the neural arches. Some anatomic changes related to the vertebral column and unpaired fins of the genus are also discussed.展开更多
In the last 15 years,the discovery of several new actinopterygian fish faunas from the Early and Middle Triassic of the Tethys,cast new light on the timing,speed and range of their recovery after the end-Permian...In the last 15 years,the discovery of several new actinopterygian fish faunas from the Early and Middle Triassic of the Tethys,cast new light on the timing,speed and range of their recovery after the end-Permian crisis.In addition to several new taxa having been described,the stratigraphical and geographical record of many others have been greatly extended.In fact,most of the new fossiliferous sites are in southern China,thus at the Eastern end of the Tethys,and furthermore a few are somewhat older(Chaohu,Panxian,Luoping)than the major classical Western Tethys sites(Monte San Giorgio).Following these new finds,it is possible to have a better definition of the Triassic recovery stages.Indeed,after a quite short phase till the end of the Smithian(Olenekian,Early Triassic)in which a rather consistent fauna was present all around the Pangea coasts,a major radiation occurred in the Early-Middle Anisian after the new Middle Triassic fish fauna already appeared in the late Early Triassic,thus occuring well before what was previously supposed from the Alps localities.Furthermore,the new assemblages from southern China point to an early broader differentiation among the basal neopterygians rather than in the‘subholosteans’,the group that was then dominant in the Western Tethys since the Late Anisian.It stands that during the Norian a new basal neopterygian radiation gave rise to several new branches that dominated the remaining part of the Mesozoic.展开更多
基金supported bygrants from the National Natural Science Foundation ofChina(no.:40672002 and 40302009)the Program for NewCentury Excellent Talents in University(no.:NCET-07-0015)+1 种基金the Committee for Research and Exploration ofthe National Geographic Society of USA(no.:7886-05)Peking University,and was a contribution to the IGCP-572 project
文摘The Middle Triassic Panxian fauna is a physical marker and representative record of the rapid recovery of the Triassic marine ecosystem following the Early Triassic stagnant stage after the end-Permian mass extinction. Ten marine reptile taxa have been found from the 1.82-2.10 m-thick fossiliferous level in the Upper Member of the Guanling Formation, which can be subdivided into three marine reptile beds through the analysis on the stratigraphic distributions of fossil reptiles. The Lower Reptile Bed yields the sauropterygians Placodus inexpectatus Jiang et al., 2008 and Lariosaurus hongguoensis Jiang et al., 2006, the ichthyopterygians Xinminosaurus catactes Jiang et al., 2008 and Phalarodon cf. Phalarodon fraasi Merriam, 1910, associated with Mixosaurus panxianensis Jiang et al., 2006, representing a stage of predominance of durophagous taxa. In this bed, the large complete skeletons may reach up to 2.3 m in length, and lithofacies and chemostratigraphic analyses indicate a relatively deep carbonate platform with an oxic water environment near the bottom, as well as a rising sea level The Middle Reptile Bed yields the sauropterygian Nothosaurus yangjuanensis Jiang et al., 2006 and the archosaur Qianosuchus mixtus Li et al., 2006, associated with Mixosaurus panxianensis Jiang et al., 2006. The fossils in this bed are characterized by its pincering dentition and large overall body size, with the largest possibly exceeding 3 m in length. This bed might represent a time of deepest basin with relatively anoxic condition near the bottom. The Upper Reptile Bed yields the sauropterygians Wumengosaurus delicatomandibularis Jiang et al., 2008, Keichousaurus sp., the protorosaur Dinocephalosaurus orientalis Li, 2003, and the ichthyopterygian Mixosaurus panxianensis Jiang et al., 2006. In this bed, reptilian taxa characterized by suction feeding appeared, and most are less than 1 m long. This bed corresponds to a period of decreasing water depth.
基金supported by Peking University and NSFC(grant 40702001)by a grant from UNIMI Chancellorand FIRST funds for the Italian team
文摘Two complete specimens from the Pelsonian （Middle Anisian, Middle Triassic） of Luoping, Yunnan Province, South China are referred to a new actinopterygian genus, Luopingichthys gen. nov., and ascribed to the perleidiform family Polzbergidae based especially on a typical synapomorphy of a peculiar premaxillary-maxillary complex, i.e., the fusion between premaxillary and maxillary along the antero-dorsal margin of the maxillary. The new taxon differs from other deep-bodied representatives of the family, Felberia and Stoppania, in its fusiform or deep fusiform body shape; sickle-shaped preopercular with short infraorbital process; lack of modified scales at the base of the anal fin; the short-based dorsal fin; scarcely ornamented scales; and thin anterior teeth. Based on a redescription of the holotype of the taxon Ctenognathichthys hattichi from the Middle Triassic （Ladinian） Prosanto Formation, Canton Graubiinden, eastern Switzerland, the only known specimen, which shows the same fusion between premaxillary and maxillary, the systematic position of the species is clarified and the taxon is proposed to be a further representative of the family Polzbergidae, and is transferred to the new genus.
基金supported by theNSFC(grants no.40572004 and 40702001)
文摘Saurichthys dawaziensis sp. nov., from the third member of the Gejiu Formation （Anisian of Middle Triassic） in the vicinity of Luoping, Yunnan Province, is a small to mediumsized saurichthyid fish. It is characterized by the efferent pseudobranchial arteries penetrating on the parasphenoid and the mandible sensory canal with a branch in the angular. The new species is more derived than the Lower Triassic species in having a relatively narrow postorbital region, short preopercular, single ossification of the sclerotic ring, small haemal arches between the pelvic fins and the anal fin without ossified spines, and in the absence of quadratojugal. It is more primitive than the Middle and Upper Triassic Saurichthys in having fringing fulcra and numerous segments in the unpaired fins, and the presence of both prae- and post-zygapophyses in the neural arches. Some anatomic changes related to the vertebral column and unpaired fins of the genus are also discussed.
文摘In the last 15 years,the discovery of several new actinopterygian fish faunas from the Early and Middle Triassic of the Tethys,cast new light on the timing,speed and range of their recovery after the end-Permian crisis.In addition to several new taxa having been described,the stratigraphical and geographical record of many others have been greatly extended.In fact,most of the new fossiliferous sites are in southern China,thus at the Eastern end of the Tethys,and furthermore a few are somewhat older(Chaohu,Panxian,Luoping)than the major classical Western Tethys sites(Monte San Giorgio).Following these new finds,it is possible to have a better definition of the Triassic recovery stages.Indeed,after a quite short phase till the end of the Smithian(Olenekian,Early Triassic)in which a rather consistent fauna was present all around the Pangea coasts,a major radiation occurred in the Early-Middle Anisian after the new Middle Triassic fish fauna already appeared in the late Early Triassic,thus occuring well before what was previously supposed from the Alps localities.Furthermore,the new assemblages from southern China point to an early broader differentiation among the basal neopterygians rather than in the‘subholosteans’,the group that was then dominant in the Western Tethys since the Late Anisian.It stands that during the Norian a new basal neopterygian radiation gave rise to several new branches that dominated the remaining part of the Mesozoic.
