＂Splitting＂ and ＂lumping＂ are perpetual problems in vertebrate, especially dinosaur, ichnotaxonomy. Chinese dinosaur ichnotaxonomy, which began in 1940, provides a series of interesting case studies, highlighting ...＂Splitting＂ and ＂lumping＂ are perpetual problems in vertebrate, especially dinosaur, ichnotaxonomy. Chinese dinosaur ichnotaxonomy, which began in 1940, provides a series of interesting case studies, highlighting the dual problems of historical and dubious ichnotaxonomy. Chinese Mesozoic tetrapod track types have been placed into 63 ichnospecies （one Triassic, 28 Jurassic, and 34 Cretaceous）, exclusive of other, non-type ichnospecies or ichnotaxa identified from China. Fifty-two （~83%） of these 63 tetrapod ichnospecies were placed in monospecific ichnogenera. At the ichnogenus level, we prune---either by recognizing nomina dubia or by synonymy--17 from the list of 53 dinosaurian ichnogenera （a 32% reduction）, leaving 36 ichnotaxa that we consider valid. Most of the cuts affect Jurassic theropod ichnotaxa, which are reduced from 23 to only nine because most ichnogenera are subjective junior synonyms of Grallator and Eubrontes. Fewer Chinese Cretaceous ichnotaxa （only six of 21 ichnogenera） are obvious nomina dubia or subjective synonyms, suggesting greater east Asian endemism during this time. Because ichnospecies differences are subtle, we provisionally retain ichnospecies as valid pending detailed comparative analyses of congeneric ichnospecies. This synthesis is long overdue and is necessary to address problems of historical and provincial ichnotaxonomy, which severely hamper comparisons of tetrapod ichnofaunas in space and time.展开更多
Three-dimensional tracks provide unique insights into the locomotor mechanics of their track makers. An isolated, large hadrosauriform print attributable to Caririchnium lotus from the ＂mid＂-Cretaceous Lotus track s...Three-dimensional tracks provide unique insights into the locomotor mechanics of their track makers. An isolated, large hadrosauriform print attributable to Caririchnium lotus from the ＂mid＂-Cretaceous Lotus track site （Jiaguan Formation） in China permits reconstruction of the footfall, weight-bearing, and kick-off phases of the step cycle. Large-scale modifications of the pes during the step cycle indicate C. lotus trackmakers were capable of locomotory modifications in response to substrate consistency beyond the ＂expected＂ shift between bipedal and quadrupedal postures. An unusual curvature to the trace of one of the outer digits indicates substantial transverse mobility. The remaining digits demonstrate lesser degrees of transverse movement accompanied by extension of the digits during footfall. The absence of overprinted scale-scratch marks and toe drags are consistent with a vertical kick-off of the pes and concomitant flexion of the digits. This track suggests that pedal mobility in C. lotus track makers was greater than previously suspected and has implications for reconstructions of hadrosauriform locomotion.展开更多
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
A pterosaur-bird track assemblage from a sandstone-siltstone-mudstone sequence of the Lower Cretaceous Tugulu Group of Xinjiang comprises the first pterosaur track record from this province and the largest specimen th...A pterosaur-bird track assemblage from a sandstone-siltstone-mudstone sequence of the Lower Cretaceous Tugulu Group of Xinjiang comprises the first pterosaur track record from this province and the largest specimen thus far known from China.The pterosaur tracks are assigned to the ichnogenus Pteraichnus based on the triangular overall-shape,the four elongate digit traces and the robust manual digit trace Ⅲ.Supposed trackmakers were dsungaripterid pterodactyloids whose skeletal remains are well known from the Tugulu Group.The bird tracks that occur on the same surface,are those of typical shorebirds,known from different other localities in southeast Asia.The congruence with Koreanaornis dodsoni described from the same stratigraphic level justifies an assignment to this ichnospecies.This is a further evidence of the co-occurrence of pterosaurs and birds in a typical iakeshore environment with possible seasonal alteration of water supply and aerial exposure indicated by wave ripples,mudcracks and repeated cycles of coarse to fine sediment.Pterosaurs and birds frequented the shoreline and may have fed also on the numerous invertebrates such as the Scoyenia tracemaker that left abundant burrows.展开更多
The Nyctosaurus specimen K J1 was reconstructed under the hypothesis that there is a membrane attached to the crest; the so-called headsail crest. The aerodynamic forces and moment acting on the headsail crest were an...The Nyctosaurus specimen K J1 was reconstructed under the hypothesis that there is a membrane attached to the crest; the so-called headsail crest. The aerodynamic forces and moment acting on the headsail crest were analyzed. It was shown that K J1 might adjust the angle of the headsail crest relative to the air current as one way to generate thrust （one of the aerodynamic forces, used to overcome body drag in forward flight） and that the magnitude of the thrust and moment could vary with the gesture angle and the relative location between the aerodynamic center of the headsail crest and body＇s center of gravity. Three scenarios were tested for comparison： the crest with membrane attachment, the crest without membrane attachment and the absence of a cranial crest. It was shown that the aerodynamic characteristics （increasing, maintaining and decreasing thrusts and moment） would have almost disappear in flight for the crest without membrane attachment and was non-existent without the cranial crest. It is suggested from aerodynamics evidence alone that Nyctosaurus specimen KJ1 had a membrane attached to the crest and used this reconstructed form for auxiliary flight control.展开更多
The paired cranial crests of Sinosaurus （Theropoda） have been hypothesized as too weak to resist mechanical loads during combat. Finite element analysis （FEA） is used to test this hypothesis, first with geometry o...The paired cranial crests of Sinosaurus （Theropoda） have been hypothesized as too weak to resist mechanical loads during combat. Finite element analysis （FEA） is used to test this hypothesis, first with geometry obtained through direct laser scanning of a well-preserved fossil of the crest, and then with two conceptual FE models of both crests analyzing the structure-deformation effects of fenestration. In the original fossil model, under direct loading on the dorsal faces of the crest, we found that the areas surrounding cavities on the crest experience shear stress that implies a high chance of material failure - the fracture of bone. In the conceptual model, a series of computational studies were conducted with varying loading directions. One simulation found that the shear stress and strain in the material around the cavity presented more deformation compared with the conceptual model without the cavities, and under this morphologically realistic scenario the loading conditions would result in local bone fractures. These model-based computational results indicate that the crest could not resist high loads, because it could not effectively decentralize the loading stress. Future investigations need to focus on more comprehensive computational experiments with more conditions, e.g. dynamical loading conditions, and direct palaeontological evidence.展开更多
A new species of Huaxiapterus： H. benxiensis sp. nov. is erected based on the new specimen. The diagnostic characters of Huaxiapterus benxiensis are well-developed premaxillary crest and parietal spine, the crest and...A new species of Huaxiapterus： H. benxiensis sp. nov. is erected based on the new specimen. The diagnostic characters of Huaxiapterus benxiensis are well-developed premaxillary crest and parietal spine, the crest and spine parallel and extending posterodorsally, and a shallow groove present on the dorsal surface of the anterior portion of the mandibular symphysis. The different skull morphologies of Chinese tapejarid pterosaurs indicate that they are much more diverse than the previous thought.展开更多
Objective Phoresy represents a non-parasitic association between animals of different taxa related to transportation. Members of several pseudoscorpion families are phoretic. In pseudoscorpions, phoresy may or may not...Objective Phoresy represents a non-parasitic association between animals of different taxa related to transportation. Members of several pseudoscorpion families are phoretic. In pseudoscorpions, phoresy may or may not be associated with their predatory behavior, enabling dispersal over larger distances than they could manage with their own short legs. This provides a wide distribution, and a potential food supply.展开更多
The neuroanatomy of the mid-sized theropod Sinosaurus triassicus from the Lower Jurassic Lufeng Formation, Lufeng Basin in Yunnan Province, China was studied using X-ray computed tomography. The braincase is character...The neuroanatomy of the mid-sized theropod Sinosaurus triassicus from the Lower Jurassic Lufeng Formation, Lufeng Basin in Yunnan Province, China was studied using X-ray computed tomography. The braincase is characterized by a large supraoccipital knob that is capped by a posterior projection of the parietal and two external foramina for the caudal middle cerebral vein, which is completely enclosed by the supraoccipital. The basicranium has well defined, short basipterygoid processes that project ventral to the basal tubera. The basisphenoid is expanded, projects posteroventrally, and is pierced by four pneumatic recesses. The endocranial morphology resembles that observed in other basal theropods—in particular some allosauroids—and has a strongly marked pontine flexure and a large dorsal expansion. The inner ear morphology is also similar to that observed in other basal theropods, with slender semicircular canals. The anterior semicircular canal is 20% larger than the posterior semicircular canal, and the angle formed between them is less than 90° when seen in dorsal view.展开更多
Objective The oofamily Dendroolithidae is elliptical or oblate eggs with loosely arranged dendritic eggshell units and large cavities between eggshell units (Zhang et al., 2018).Dendroolithidae is represented by two o...Objective The oofamily Dendroolithidae is elliptical or oblate eggs with loosely arranged dendritic eggshell units and large cavities between eggshell units (Zhang et al., 2018).Dendroolithidae is represented by two oogenera,Dendroolithus (Zhao Zikui and Li Zuocong, 1988), and Placoolithus (Zhao Hong and Zhao Zikui, 1998)according to the latest classification (Zhang et al., 2018).展开更多
Objective Despite a large number of bird fossils in the Jehol Biota, Mesozoic bird records from other parts of China are dominated by tracks. Late Cretaceous bird tracks are rarely found in China. Reliable reports so...Objective Despite a large number of bird fossils in the Jehol Biota, Mesozoic bird records from other parts of China are dominated by tracks. Late Cretaceous bird tracks are rarely found in China. Reliable reports so far include a Dongyangornipes and Koreanaornis assemblage of early Late Cretaceous age from Dongyang City, Zhejiang Province, China （Azuma et al., 2013）. Buckley et al. （2016） consider Dongyangornipes sinensis a subjective junior synonym of Uhangrichnus chuni. Type Uhangrichnus chuni （Yang et al. 1995; Lockley et al., 2012） from the Uhangri Formation, Hwangsan Basin of South Korea is Late Cretaceous in age, and the trackrnaker was a web-footed avian.展开更多
The trackway of a swimming theropod (ichnogenus Characichnos) is reported from the Lower Cretaceous Feitianshan Formation of Sichuan, China. These swim tracks help confirm that non-avian theropods were capable of forg...The trackway of a swimming theropod (ichnogenus Characichnos) is reported from the Lower Cretaceous Feitianshan Formation of Sichuan, China. These swim tracks help confirm that non-avian theropods were capable of forging moderately deep bodies of water. The trackway occurs on the same surface as a typical walking trackway of a sauropod (ichnogenus Brontopodus). Both occurrences are the first reported from the Cretaceous of Sichuan, and the swim tracks are the first well-preserved example of a Characichnos trackway from China. Additionally, a theropod walking trackway and several ornithopod walking trackways (similar to the ichnogenus Caririchnium) occur in the same horizon. The ornithopod trackways show a parallel orientation, suggesting gregarious behavior of the trackmakers, which may have been iguanodontiforms and/or hadrosauriforms. The co-occurrence of theropod swim tracks and theropod walking tracks suggests a fluctuation of water depth within a distinct time span.展开更多
基金supported by the National Natural Science Foundation of China(No.41790455,41772008)the National Geographic Society,USA(No.EC0768-15)+1 种基金the Fundamental Research Funds for the Central Universities(No.2652017215)the State Key Laboratory of Palaeobiology and Stratigraphy(Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences)(No.173127)
基金supported by the Grant-in-Aid for Scientific Research of the Japan Society for the Promotion of Science(to Masaki Matsukawa,no.1183303,1999-2000)the Grant-in Aid for University and Society Collaboration of the Japanese Ministry of Education, Science,Sports and Culture(to Masaki Matsukawa,no. 11791012,1999-2001)+2 种基金The Shandong portion of this study was supported financially,in part,by the National Natural Science Foundation of China grant no.40972005 to Rihui LiThe Nei Mongol portion of this study was supported by a grant from the National Natural Science Foundation of China(40872005) to Jianjun Lithe Beijing Museum of Natural History,with supplemental support from the Dinosaur Tracks Museum,University of Colorado Denver
文摘＂Splitting＂ and ＂lumping＂ are perpetual problems in vertebrate, especially dinosaur, ichnotaxonomy. Chinese dinosaur ichnotaxonomy, which began in 1940, provides a series of interesting case studies, highlighting the dual problems of historical and dubious ichnotaxonomy. Chinese Mesozoic tetrapod track types have been placed into 63 ichnospecies （one Triassic, 28 Jurassic, and 34 Cretaceous）, exclusive of other, non-type ichnospecies or ichnotaxa identified from China. Fifty-two （~83%） of these 63 tetrapod ichnospecies were placed in monospecific ichnogenera. At the ichnogenus level, we prune---either by recognizing nomina dubia or by synonymy--17 from the list of 53 dinosaurian ichnogenera （a 32% reduction）, leaving 36 ichnotaxa that we consider valid. Most of the cuts affect Jurassic theropod ichnotaxa, which are reduced from 23 to only nine because most ichnogenera are subjective junior synonyms of Grallator and Eubrontes. Fewer Chinese Cretaceous ichnotaxa （only six of 21 ichnogenera） are obvious nomina dubia or subjective synonyms, suggesting greater east Asian endemism during this time. Because ichnospecies differences are subtle, we provisionally retain ichnospecies as valid pending detailed comparative analyses of congeneric ichnospecies. This synthesis is long overdue and is necessary to address problems of historical and provincial ichnotaxonomy, which severely hamper comparisons of tetrapod ichnofaunas in space and time.
基金supported by the Key Laboratory of Evolutionary Systematics of Vertebrates,Chinese Academy Of Sciences (No. 2011LESV008)Qijiang County Bureau of Land and Resources,Chongqing,China
文摘Three-dimensional tracks provide unique insights into the locomotor mechanics of their track makers. An isolated, large hadrosauriform print attributable to Caririchnium lotus from the ＂mid＂-Cretaceous Lotus track site （Jiaguan Formation） in China permits reconstruction of the footfall, weight-bearing, and kick-off phases of the step cycle. Large-scale modifications of the pes during the step cycle indicate C. lotus trackmakers were capable of locomotory modifications in response to substrate consistency beyond the ＂expected＂ shift between bipedal and quadrupedal postures. An unusual curvature to the trace of one of the outer digits indicates substantial transverse mobility. The remaining digits demonstrate lesser degrees of transverse movement accompanied by extension of the digits during footfall. The absence of overprinted scale-scratch marks and toe drags are consistent with a vertical kick-off of the pes and concomitant flexion of the digits. This track suggests that pedal mobility in C. lotus track makers was greater than previously suspected and has implications for reconstructions of hadrosauriform locomotion.
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 Key Laboratory of Evolutionary Systematics of Vertebrates, CAS (2011LESV008)the Xinjiang Research Institute of Petroleum Exploration
文摘A pterosaur-bird track assemblage from a sandstone-siltstone-mudstone sequence of the Lower Cretaceous Tugulu Group of Xinjiang comprises the first pterosaur track record from this province and the largest specimen thus far known from China.The pterosaur tracks are assigned to the ichnogenus Pteraichnus based on the triangular overall-shape,the four elongate digit traces and the robust manual digit trace Ⅲ.Supposed trackmakers were dsungaripterid pterodactyloids whose skeletal remains are well known from the Tugulu Group.The bird tracks that occur on the same surface,are those of typical shorebirds,known from different other localities in southeast Asia.The congruence with Koreanaornis dodsoni described from the same stratigraphic level justifies an assignment to this ichnospecies.This is a further evidence of the co-occurrence of pterosaurs and birds in a typical iakeshore environment with possible seasonal alteration of water supply and aerial exposure indicated by wave ripples,mudcracks and repeated cycles of coarse to fine sediment.Pterosaurs and birds frequented the shoreline and may have fed also on the numerous invertebrates such as the Scoyenia tracemaker that left abundant burrows.
基金supported by the Chinese Ministry of Science and Technology (973 Project,2006CB701405)China Geological Survey,National Geographic (China Edition)and China Aviation Media Group.
文摘The Nyctosaurus specimen K J1 was reconstructed under the hypothesis that there is a membrane attached to the crest; the so-called headsail crest. The aerodynamic forces and moment acting on the headsail crest were analyzed. It was shown that K J1 might adjust the angle of the headsail crest relative to the air current as one way to generate thrust （one of the aerodynamic forces, used to overcome body drag in forward flight） and that the magnitude of the thrust and moment could vary with the gesture angle and the relative location between the aerodynamic center of the headsail crest and body＇s center of gravity. Three scenarios were tested for comparison： the crest with membrane attachment, the crest without membrane attachment and the absence of a cranial crest. It was shown that the aerodynamic characteristics （increasing, maintaining and decreasing thrusts and moment） would have almost disappear in flight for the crest without membrane attachment and was non-existent without the cranial crest. It is suggested from aerodynamics evidence alone that Nyctosaurus specimen KJ1 had a membrane attached to the crest and used this reconstructed form for auxiliary flight control.
文摘The paired cranial crests of Sinosaurus （Theropoda） have been hypothesized as too weak to resist mechanical loads during combat. Finite element analysis （FEA） is used to test this hypothesis, first with geometry obtained through direct laser scanning of a well-preserved fossil of the crest, and then with two conceptual FE models of both crests analyzing the structure-deformation effects of fenestration. In the original fossil model, under direct loading on the dorsal faces of the crest, we found that the areas surrounding cavities on the crest experience shear stress that implies a high chance of material failure - the fracture of bone. In the conceptual model, a series of computational studies were conducted with varying loading directions. One simulation found that the shear stress and strain in the material around the cavity presented more deformation compared with the conceptual model without the cavities, and under this morphologically realistic scenario the loading conditions would result in local bone fractures. These model-based computational results indicate that the crest could not resist high loads, because it could not effectively decentralize the loading stress. Future investigations need to focus on more comprehensive computational experiments with more conditions, e.g. dynamical loading conditions, and direct palaeontological evidence.
文摘A new species of Huaxiapterus： H. benxiensis sp. nov. is erected based on the new specimen. The diagnostic characters of Huaxiapterus benxiensis are well-developed premaxillary crest and parietal spine, the crest and spine parallel and extending posterodorsally, and a shallow groove present on the dorsal surface of the anterior portion of the mandibular symphysis. The different skull morphologies of Chinese tapejarid pterosaurs indicate that they are much more diverse than the previous thought.
基金funded by the Natural Sciences and Engineering Research Council of Canada (2015-00681)the National Geographic Society, USA (EC0768-15)+1 种基金National Natural Science Foundation of China (No. 41772008)National Natural Science Foundation of China (No. 31872198)
文摘Objective Phoresy represents a non-parasitic association between animals of different taxa related to transportation. Members of several pseudoscorpion families are phoretic. In pseudoscorpions, phoresy may or may not be associated with their predatory behavior, enabling dispersal over larger distances than they could manage with their own short legs. This provides a wide distribution, and a potential food supply.
文摘The neuroanatomy of the mid-sized theropod Sinosaurus triassicus from the Lower Jurassic Lufeng Formation, Lufeng Basin in Yunnan Province, China was studied using X-ray computed tomography. The braincase is characterized by a large supraoccipital knob that is capped by a posterior projection of the parietal and two external foramina for the caudal middle cerebral vein, which is completely enclosed by the supraoccipital. The basicranium has well defined, short basipterygoid processes that project ventral to the basal tubera. The basisphenoid is expanded, projects posteroventrally, and is pierced by four pneumatic recesses. The endocranial morphology resembles that observed in other basal theropods—in particular some allosauroids—and has a strongly marked pontine flexure and a large dorsal expansion. The inner ear morphology is also similar to that observed in other basal theropods, with slender semicircular canals. The anterior semicircular canal is 20% larger than the posterior semicircular canal, and the angle formed between them is less than 90° when seen in dorsal view.
基金supported by the National Natural Science Foundation of China (grant No. 41802006)the Natural Science Foundation of Anhui Province (grant No. 1708085QD86)the University Natural Science Research Project of Anhui Province (grant No. KJ2018A0005)
文摘Objective The oofamily Dendroolithidae is elliptical or oblate eggs with loosely arranged dendritic eggshell units and large cavities between eggshell units (Zhang et al., 2018).Dendroolithidae is represented by two oogenera,Dendroolithus (Zhao Zikui and Li Zuocong, 1988), and Placoolithus (Zhao Hong and Zhao Zikui, 1998)according to the latest classification (Zhang et al., 2018).
基金supported by State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, CAS) (No.173127)the Fundamental Research Funds for the Central Universities (No.2652017215)
文摘Objective Despite a large number of bird fossils in the Jehol Biota, Mesozoic bird records from other parts of China are dominated by tracks. Late Cretaceous bird tracks are rarely found in China. Reliable reports so far include a Dongyangornipes and Koreanaornis assemblage of early Late Cretaceous age from Dongyang City, Zhejiang Province, China （Azuma et al., 2013）. Buckley et al. （2016） consider Dongyangornipes sinensis a subjective junior synonym of Uhangrichnus chuni. Type Uhangrichnus chuni （Yang et al. 1995; Lockley et al., 2012） from the Uhangri Formation, Hwangsan Basin of South Korea is Late Cretaceous in age, and the trackrnaker was a web-footed avian.
基金supported by Key Laboratory of Evolutionary Systematics of Vertebrates,Chinese Academy Sciences (2011LESV008)
文摘The trackway of a swimming theropod (ichnogenus Characichnos) is reported from the Lower Cretaceous Feitianshan Formation of Sichuan, China. These swim tracks help confirm that non-avian theropods were capable of forging moderately deep bodies of water. The trackway occurs on the same surface as a typical walking trackway of a sauropod (ichnogenus Brontopodus). Both occurrences are the first reported from the Cretaceous of Sichuan, and the swim tracks are the first well-preserved example of a Characichnos trackway from China. Additionally, a theropod walking trackway and several ornithopod walking trackways (similar to the ichnogenus Caririchnium) occur in the same horizon. The ornithopod trackways show a parallel orientation, suggesting gregarious behavior of the trackmakers, which may have been iguanodontiforms and/or hadrosauriforms. The co-occurrence of theropod swim tracks and theropod walking tracks suggests a fluctuation of water depth within a distinct time span.
