New findings of galeaspids(Agnatha)including Altigibbaspis huiqingae gen.et sp.nov.,an indeterminate polybranchiaspid,Eugaleaspis changi,and Nanpanaspis microculus are described from the lower part of the Xishancun Fo...New findings of galeaspids(Agnatha)including Altigibbaspis huiqingae gen.et sp.nov.,an indeterminate polybranchiaspid,Eugaleaspis changi,and Nanpanaspis microculus are described from the lower part of the Xishancun Formation(early Lochkovian,Early Devonian)near the northeast entrance of Liaokuo Park,Qujing City,Yunnan Province,China.The Polybranchiaspis-like new genus is characterized by a blade-like median dorsal ridge on the dorsal side of head-shield.The morphological disparity of the median dorsal ridge and spine in galeaspids suggests that these structures functioned more than providing a hydrodynamic stability.We assume that a high upright and compressed spine may render galeaspid fishes an apparently larger size as seen by a predator,and a blade-like median dorsal ridge may accomplish a defense against the claws of large sea scorpions.Nanpanaspis is peculiar in bearing two short laterally projecting processes on each side of the head-shield,and its phylogenetic relationship is discussed based on different interpretations on the homology of these processes.Considering the unique morphology of Nanpanaspis,and its early occurrence among the Huananaspiformes,we assign Nanpanaspis in the monogeneric family Nanpanaspidae to represent an early branch of the Huananaspiformes.展开更多
A new species of Shuyuidae(Eugaleaspiformes,Galeaspida),Jiangxialepis jiujiangensis sp.nov.,is described from the lower Telychian(Llandovery,Silurian)Qingshui Formation in Jiujiang,Jiangxi Province,China.The new speci...A new species of Shuyuidae(Eugaleaspiformes,Galeaspida),Jiangxialepis jiujiangensis sp.nov.,is described from the lower Telychian(Llandovery,Silurian)Qingshui Formation in Jiujiang,Jiangxi Province,China.The new species differs from the type species J.retrospina from Wuhan,Hubei Province in its sharp and posteriorly positioned median dorsal spine and narrow spine-shaped inner cornual processes.The Silurian strata in Xiushui–Wuning area has provided a standard framework for the correlation of Silurian shallow marine red beds in South China.Thus,the finding of J.jiujiangensis from the Silurian Lower Red Beds(LRBs)in Jiangxi Province bears very important biostratigraphic significance.It can directly compare to Jiangxialepis retrospina from the Fentou Formation in Wuhan,Hubei Province in the genus level.This indicates that the age of the fish-bearing strata in Wuhan is most likely to be the early Telychian rather than middle Telychian as previously assumed.展开更多
New discovery of the early Silurian fossil fish Changxingaspis(Xiushuiaspidae,Galeaspida),Changxingaspis nianzhongi sp.nov.and C.gui,are described from the Tataertag Formation in Tarim Basin and the Kangshan Formation...New discovery of the early Silurian fossil fish Changxingaspis(Xiushuiaspidae,Galeaspida),Changxingaspis nianzhongi sp.nov.and C.gui,are described from the Tataertag Formation in Tarim Basin and the Kangshan Formation in Zhejiang Province,respectively.C.nianzhongi mainly differs from C.gui in the shape of the median dorsal opening that is transverse elliptic with a width/length ratio of about 3.0,the long lateral transverse canals extending to the lateral margin of the headshield,and the second lateral transverse canal with dichotomous branchings.Discovery of C.nianzhongi from the Tataertag Formation and C.gui from the Kangshan Formation provide direct evidence on the specific level for the correlation between these two formations,which further supports the Silurian fish-bearing red beds in northwest Zhejiang belonging to the Silurian Lower Red Beds(LRBs)rather than the Upper Red Beds(URBs).Additionally,as the first record of the Changxingaspis in Tarim Basin,it extends the paleogeographical distribution of this genus from the South China Block to the Tarim Block,providing new evidence to support faunal exchanges between these two blocks and the hypothesis of a united Tarim-South China Block during the early Silurian.展开更多
文摘New findings of galeaspids(Agnatha)including Altigibbaspis huiqingae gen.et sp.nov.,an indeterminate polybranchiaspid,Eugaleaspis changi,and Nanpanaspis microculus are described from the lower part of the Xishancun Formation(early Lochkovian,Early Devonian)near the northeast entrance of Liaokuo Park,Qujing City,Yunnan Province,China.The Polybranchiaspis-like new genus is characterized by a blade-like median dorsal ridge on the dorsal side of head-shield.The morphological disparity of the median dorsal ridge and spine in galeaspids suggests that these structures functioned more than providing a hydrodynamic stability.We assume that a high upright and compressed spine may render galeaspid fishes an apparently larger size as seen by a predator,and a blade-like median dorsal ridge may accomplish a defense against the claws of large sea scorpions.Nanpanaspis is peculiar in bearing two short laterally projecting processes on each side of the head-shield,and its phylogenetic relationship is discussed based on different interpretations on the homology of these processes.Considering the unique morphology of Nanpanaspis,and its early occurrence among the Huananaspiformes,we assign Nanpanaspis in the monogeneric family Nanpanaspidae to represent an early branch of the Huananaspiformes.
基金supported by the Strategic Priority Research Program of CAS(XDB26000000)Key Research Program of Frontier Sciences,CAS(QYZDB-SSWDQC040)+1 种基金National Natural Science Foundation of China(41972006,42072026)National Program for Support of Topnotch Young Professionals(W02070206)。
文摘A new species of Shuyuidae(Eugaleaspiformes,Galeaspida),Jiangxialepis jiujiangensis sp.nov.,is described from the lower Telychian(Llandovery,Silurian)Qingshui Formation in Jiujiang,Jiangxi Province,China.The new species differs from the type species J.retrospina from Wuhan,Hubei Province in its sharp and posteriorly positioned median dorsal spine and narrow spine-shaped inner cornual processes.The Silurian strata in Xiushui–Wuning area has provided a standard framework for the correlation of Silurian shallow marine red beds in South China.Thus,the finding of J.jiujiangensis from the Silurian Lower Red Beds(LRBs)in Jiangxi Province bears very important biostratigraphic significance.It can directly compare to Jiangxialepis retrospina from the Fentou Formation in Wuhan,Hubei Province in the genus level.This indicates that the age of the fish-bearing strata in Wuhan is most likely to be the early Telychian rather than middle Telychian as previously assumed.
基金supported by the National Natural Science Foundation of China(Grant Nos.92255301,41972006,42072026,42130209)Mee-mann Chang Academician Workstation in Yunnan Province(Grant No.202205AF150002)。
文摘New discovery of the early Silurian fossil fish Changxingaspis(Xiushuiaspidae,Galeaspida),Changxingaspis nianzhongi sp.nov.and C.gui,are described from the Tataertag Formation in Tarim Basin and the Kangshan Formation in Zhejiang Province,respectively.C.nianzhongi mainly differs from C.gui in the shape of the median dorsal opening that is transverse elliptic with a width/length ratio of about 3.0,the long lateral transverse canals extending to the lateral margin of the headshield,and the second lateral transverse canal with dichotomous branchings.Discovery of C.nianzhongi from the Tataertag Formation and C.gui from the Kangshan Formation provide direct evidence on the specific level for the correlation between these two formations,which further supports the Silurian fish-bearing red beds in northwest Zhejiang belonging to the Silurian Lower Red Beds(LRBs)rather than the Upper Red Beds(URBs).Additionally,as the first record of the Changxingaspis in Tarim Basin,it extends the paleogeographical distribution of this genus from the South China Block to the Tarim Block,providing new evidence to support faunal exchanges between these two blocks and the hypothesis of a united Tarim-South China Block during the early Silurian.
