In the Linxia Basin on the northeast margin of the Tibetan Plateau, the Cenozoic strata are very thick and well exposed. Abundant mammalian fossils are discovered in the deposits from the Late Oligocene to the Early P...In the Linxia Basin on the northeast margin of the Tibetan Plateau, the Cenozoic strata are very thick and well exposed. Abundant mammalian fossils are discovered in the deposits from the Late Oligocene to the Early Pleistocene. The Dzungariotherium fauna comes from the sandstones of the Jiaozigou Formation, including many representative Late Oligocene taxa. The Platybelodon fauna comes from the sandstones of the Dongxiang Formation and the conglomerates of the Laogou Formation, and its fossils are typical Middle Miocene forms, such as Hemicyon, Amphicyon, Platybelodon, Choerolophodon, Anchitherium, and Hispanotherium. The Hipparion fauna comes from the red clay of the Liushu and Hewangjia Formations, and its fossils can be distinctly divided into four levels, including three Late Miocene levels and one Early Pliocene level. In the Linxia Basin, the Hipparion fauna has the richest mammalian fossils. The Equus fauna comes from the Wucheng Loess, and it is slightly older than that of the classical Early Pleistocene Nihewan Fauna. The mammalian faunas from the Linxia Basin provide the reliable evidence to divide the Cenozoic strata of this basin and correlate them with European mammalian sequence.展开更多
A specimen collected from the Lower Cretaceous Yixian Formation of western Liaoning, China, represents a new genus and species of troodontid theropod. The new taxon is named and described on the basis of the holotype ...A specimen collected from the Lower Cretaceous Yixian Formation of western Liaoning, China, represents a new genus and species of troodontid theropod. The new taxon is named and described on the basis of the holotype and the only known specimen, which comprises an articulated skeleton with the presacral vertebral, shoulder girdle and forelimbs missing as preserved. Diagnostic features of the new species include nasals that are sinusoid in lateral view, absence of a passage connecting the antorbital and maxillary fenestrae, relatively large teeth, plate-like chevrons forming a band along most of the length of the tail, and a long neck between the femoral head and shaft. The temporal constraints of the three paravian groups (Troodontidae, Dromaeosauridae and Aves) combined with the character distributions among the earliest known troodontids indicate a rapid evolution at the base of the Troodontidae.展开更多
A new dinosaur of Early Cretaceous age was recently discovered from the Mazongshan area of northwestern Gansu Province, China. The new dinosaur represents a new genus and species of Sauropoda, and is among the most ba...A new dinosaur of Early Cretaceous age was recently discovered from the Mazongshan area of northwestern Gansu Province, China. The new dinosaur represents a new genus and species of Sauropoda, and is among the most basal members of Titanosauria. Its finding also suggests that titanosaurs might have originated in Asia no later than the Early Cretaceous.展开更多
An almost complete skull, which was collected from the Upper Cretaceous of the Bayan Mandahu area in Inner Mongolia, China by the Sino-Canadian Dinosaur Project, is described and assigned to a new genus of protocerato...An almost complete skull, which was collected from the Upper Cretaceous of the Bayan Mandahu area in Inner Mongolia, China by the Sino-Canadian Dinosaur Project, is described and assigned to a new genus of protoceratopsid dinosaur, Magnirostris dodsoni gen. et sp. nov. This new taxon is distinguished from other protoceratopsids by the robust rostral bone and the existence of incipient orbital horn cores. The existence of an additional antorbital fenestra indicates a close relationship between Magnirostris and Bagaceratops.展开更多
Pygostyle was previously considered as a unique structure of ornithothoracine birds, used to maneuver tail feathers. A similar structure from an oviraptorosaurian dinosaur was considered functionally associated with t...Pygostyle was previously considered as a unique structure of ornithothoracine birds, used to maneuver tail feathers. A similar structure from an oviraptorosaurian dinosaur was considered functionally associated with the rectrices as in birds. We report a pygostyle-like structure from a therizinosauroid dinosaur. The presence of filamentous integuments, but absence of rectrices, on the tail of this therizinosauroid, combined with other lines of evidence, suggests that the initial function of the pygostyle was not related to the rectrices.展开更多
A new specimen consisting of a complete skull and lower jaw was discovered from the Lujiatun bed of the Lower Cretaceous Yixian Formation in the Lujiatun site, Beipiao, western Liaoning Province. It represents an adul...A new specimen consisting of a complete skull and lower jaw was discovered from the Lujiatun bed of the Lower Cretaceous Yixian Formation in the Lujiatun site, Beipiao, western Liaoning Province. It represents an adult specimen of Hongshanosaurus houi. Comparative studies show that Hongshanosaurus is distinguishable from its sister taxon Psittacosaurus by having the preorbital portion about half of the basal skull length, and the elliptical external naris, orbit, and a lower temporal fenestra oriented caudodorsally.展开更多
A Iarge number of enantiornithine birds are discovered from the Early Cretaceous Jiufutang Formation in western Liaoning, China. They are all small-sized birds with a few small teeth. The enantiornithine bird from the...A Iarge number of enantiornithine birds are discovered from the Early Cretaceous Jiufutang Formation in western Liaoning, China. They are all small-sized birds with a few small teeth. The enantiornithine bird from the Jiufutang Formation in the Shangheshou area, Chaoyang, Liaoning Province reported in this paper is the largest individual known in all enantiornithine birds of the Early Cretaceous. However, its teeth possess a feature of pseudoheterodont. Some different development stages of the new teeth substitute the earlier stages and the stages of development are preserved in this specimen. This development pattern is similar to that of Archaeopteryx and alligator but not dinosaur. A well-developed postorbital was also preserved in the skull, which was a diapsidian skull like that of Confuciusornis. Additionally, the distinctive preservation of its prefrontal distinguishes it from other enantiornithine birds of the Early Cretaceous.展开更多
Three anurans (Callobatrachus sanyanensis, Liaobatrachus grabaui, Mesophryne beipiaoensis) and six urodeles (Laccotriton subsolanus, Liaoxitriton zhongjiani, Jeholotriton paradoxus, Sinerpeton fengshanensis, Chunerpet...Three anurans (Callobatrachus sanyanensis, Liaobatrachus grabaui, Mesophryne beipiaoensis) and six urodeles (Laccotriton subsolanus, Liaoxitriton zhongjiani, Jeholotriton paradoxus, Sinerpeton fengshanensis, Chunerpeton tianyiensis, Liaoxitriton daohugouensis) are reported from the late Mesozoic tuff-interbedded lacustrine deposits (mostly of the Jehol Group) in northeastern China. They document the first discovery of Chinese Mesozoic lissamphibians, and their old geological age, superb preservation condition, and large taxoncmic diversity are unique compared with other findings worldwide. The anurans occupy a higher evolutionary position than typical Jurassic taxa, supporting a post-Late Jurassic age of the fossil horizons. The urodeles all have unicapitate ribs, suggesting an evolutionary grade at the cryptobranchoid level, and are advanced in osteological features over non-urodeles from the Middle and Upper Jurassic in England and Central Asia. Some urodeles (Jeholotriton and Chunerpeton) exhibit neotenic features, representing the earliest occurrence among such findings. Six fossil horizons are rscognized for the known Chinese Mesozoic anurans and urodeles: the Daohugou fossil bed, the Dabeigou Formation, the Lujiatun Bed, Jianshangou Bed and Dawangzhangzi Bed of the Yixian Formation, and the Jiufotang Formation. As implied from the osteological and phylogenetical studies, the geological age of these anurans and urodeles is the Early Cretaceous.展开更多
Carbon isotope analysis of modern herbaceous plants in the Gyirong Basin (Tibet, China) indicates that although C3 plants are dominant, C4 plants rarely comprise of the vegetation in the area at 4000 m above sea level...Carbon isotope analysis of modern herbaceous plants in the Gyirong Basin (Tibet, China) indicates that although C3 plants are dominant, C4 plants rarely comprise of the vegetation in the area at 4000 m above sea level. The C4 plants discovered in the Gyirong Basin are Salsola nepalensis of Chenopodiaceae and Pennisetum flaccidum of Gramineae, affirming that C4 plants affected by high solar gain can be distributed at high altitude, which supports the opinion that some C4 plants can exist in areas of high elevation. Carbon isotope analysis of herbivore tooth enamel from the Gyirong Basin indicates that carbon isotopes of structural carbonate in biogenic apatite at high altitude still keep a stable enrichment relationship with those of plants in their diet. Carbon isotopes in tooth enamel are therefore an accurate proxy for vegetation ecotypes and should reflect climatic and environmental features.展开更多
Hunter-gatherer populations in greater northeast Asia experienced dramatic range expansions during the early Upper Paleolithic (45—22 ka) and the late Upper Paleolithic (18—10 ka), both of which led to intensive occ...Hunter-gatherer populations in greater northeast Asia experienced dramatic range expansions during the early Upper Paleolithic (45—22 ka) and the late Upper Paleolithic (18—10 ka), both of which led to intensive occupations of cold desert environments including the Mongolian Gobi and northwest China. Range contractions under the cold, arid extremes of the Last Glacial Maximum (LGM, 22—18 ka) may have entailed widespread population extirpations. The high elevation Qinghai-Tibetan Plateau is significantly more extreme in both climate and environment than either the Gobi or the Siberian taiga forests, and provides an ideal setting to test fundamental models of human biogeog- raphy in the context of regional population fluctuations. The area is presently occupied primarily by nomadic pastoralists, but it is clear that these complex middle Holocene (<6 ka) economic adaptations were not a necessary prerequisite for successful colonization of the high elevation Plateau. Exploratory field-work in 2000—2001 has established that Upper Paleolithic hunter-gatherers were present on the Qinghai-Tibetan Plateau by at least 12 ka and possibly much earlier. A speculative model for the colonization process is developed and preliminary archaeological data in support of the model are presented.展开更多
The Tianyuan Cave is the only human fos-sil-bearing site containing rich mammalian fossils found in the last decades near Zhoukoudian. Up to now more than 34 specimens of the human body have been recovered, and the ma...The Tianyuan Cave is the only human fos-sil-bearing site containing rich mammalian fossils found in the last decades near Zhoukoudian. Up to now more than 34 specimens of the human body have been recovered, and the mammalian fossils can be put into 29 species. Cervids domi-nate the fauna, and carnivores are very rare. Based on the primary examination, the human fossils can be attributed to the species Homo sapiens. All the mammalian fossils, except one between tooth of Crocuta belong to the species that still exist today. But some of them are the first records in fossil form north of the Yellow River, such as Arctonyx and Capri-cornis. Based on the mammalian fauna study, it seems that the Tianyuan Cave can be correlated with the Upper Cave. Sixty-three percent of the species of the mammalian fauna from the Tianyuan Cave are also present in the Upper Cave. The characters of the deposits also share some similarities between the Tianyuan Cave and the Upper Cave; both of them are mainly composed of breccia without cement. The dating using the U-series method on deer tooth samples in-dicates that the geological age of the new site is around 25 thousand years B.P. This is the first discovery of human sites outside the core area of the Peking Man Site at Zhoukoudian, which throws new light onto this world famous site complex.展开更多
Rich paleoanthropological materials were unearthed in primary context from the Xinglongdong Cave in Fengjie County, Chongqing, South China, including a human tooth, numerous mammalian fossils, some stone artifacts and...Rich paleoanthropological materials were unearthed in primary context from the Xinglongdong Cave in Fengjie County, Chongqing, South China, including a human tooth, numerous mammalian fossils, some stone artifacts and a Stegodon tusk exhibiting intentional engravings.Based on biostratigraphic data and uranium series dating,the cave was utilized as a human shelter about 120000-150000 years ago. It is the first time that an archaic Homo sapiens fossil has been unearthed from the Three Gorges Region. Engravings on the Stegodon tusk appear in groups,making up simple and abstract images. It is the earliest known engravings created by human beings; it exhibits great potential for the study of the origin of art and the development of ancient cultures in south China and bears important implications for the origin of modern humans in East Asia.展开更多
The Yuanmou Basin of Yunnan Province is ahotspot for the research of early hominid evolution and its environmental background. During the implementation ofthe Program 揜esearch of the Origin and Evolution of Early Man...The Yuanmou Basin of Yunnan Province is ahotspot for the research of early hominid evolution and its environmental background. During the implementation ofthe Program 揜esearch of the Origin and Evolution of Early Man and Its Environmental Background?from 1998 to 2001, a huge quantity of hominoid and mammal fossils were col-lected. The present report systematically describes an Eu-prox robustus sp. nov. identified during the recent laboratory work on the collected material. Euprox is a group of earliest cervids with true antlers. The new species is the third one of the genus discovered in China. Judged by its morphologiccharacteristics, the new species feed on juicy and tenderleaves of dicotyledon. It implies that the vegetation of itsepoch in the Yuanmou Basin is a kind of southern subtropi-cal evergreen forest and the climate is humid and temperate with evident seasonality. The latter is mostly influenced by the monsoon and secondly by the latitude.展开更多
基金the National Natural Science Foundation of China(No.40232023)Chinese Academy of Sciences(No.KZCX2-103,RJZ2001-105)Ministry of Science and Technology of China(No.G2000077700).
文摘In the Linxia Basin on the northeast margin of the Tibetan Plateau, the Cenozoic strata are very thick and well exposed. Abundant mammalian fossils are discovered in the deposits from the Late Oligocene to the Early Pleistocene. The Dzungariotherium fauna comes from the sandstones of the Jiaozigou Formation, including many representative Late Oligocene taxa. The Platybelodon fauna comes from the sandstones of the Dongxiang Formation and the conglomerates of the Laogou Formation, and its fossils are typical Middle Miocene forms, such as Hemicyon, Amphicyon, Platybelodon, Choerolophodon, Anchitherium, and Hispanotherium. The Hipparion fauna comes from the red clay of the Liushu and Hewangjia Formations, and its fossils can be distinctly divided into four levels, including three Late Miocene levels and one Early Pliocene level. In the Linxia Basin, the Hipparion fauna has the richest mammalian fossils. The Equus fauna comes from the Wucheng Loess, and it is slightly older than that of the classical Early Pleistocene Nihewan Fauna. The mammalian faunas from the Linxia Basin provide the reliable evidence to divide the Cenozoic strata of this basin and correlate them with European mammalian sequence.
基金the National Natural Science Foundation of ChinaNational Geographic Socicty+1 种基金Special Funds for Major State Basic Research Projects of China Chinese Acalemy of Sciences for financial support.
文摘A specimen collected from the Lower Cretaceous Yixian Formation of western Liaoning, China, represents a new genus and species of troodontid theropod. The new taxon is named and described on the basis of the holotype and the only known specimen, which comprises an articulated skeleton with the presacral vertebral, shoulder girdle and forelimbs missing as preserved. Diagnostic features of the new species include nasals that are sinusoid in lateral view, absence of a passage connecting the antorbital and maxillary fenestrae, relatively large teeth, plate-like chevrons forming a band along most of the length of the tail, and a long neck between the femoral head and shaft. The temporal constraints of the three paravian groups (Troodontidae, Dromaeosauridae and Aves) combined with the character distributions among the earliest known troodontids indicate a rapid evolution at the base of the Troodontidae.
文摘A new dinosaur of Early Cretaceous age was recently discovered from the Mazongshan area of northwestern Gansu Province, China. The new dinosaur represents a new genus and species of Sauropoda, and is among the most basal members of Titanosauria. Its finding also suggests that titanosaurs might have originated in Asia no later than the Early Cretaceous.
文摘An almost complete skull, which was collected from the Upper Cretaceous of the Bayan Mandahu area in Inner Mongolia, China by the Sino-Canadian Dinosaur Project, is described and assigned to a new genus of protoceratopsid dinosaur, Magnirostris dodsoni gen. et sp. nov. This new taxon is distinguished from other protoceratopsids by the robust rostral bone and the existence of incipient orbital horn cores. The existence of an additional antorbital fenestra indicates a close relationship between Magnirostris and Bagaceratops.
基金supported by grants from the National Natural Science Foundation of China(No.40125006)the Special Funds for Major State Basic Research Projects of China(No.G2000077700)the Chinese Academy of Sciences(No.KZCX3-J-03).
文摘Pygostyle was previously considered as a unique structure of ornithothoracine birds, used to maneuver tail feathers. A similar structure from an oviraptorosaurian dinosaur was considered functionally associated with the rectrices as in birds. We report a pygostyle-like structure from a therizinosauroid dinosaur. The presence of filamentous integuments, but absence of rectrices, on the tail of this therizinosauroid, combined with other lines of evidence, suggests that the initial function of the pygostyle was not related to the rectrices.
文摘A new specimen consisting of a complete skull and lower jaw was discovered from the Lujiatun bed of the Lower Cretaceous Yixian Formation in the Lujiatun site, Beipiao, western Liaoning Province. It represents an adult specimen of Hongshanosaurus houi. Comparative studies show that Hongshanosaurus is distinguishable from its sister taxon Psittacosaurus by having the preorbital portion about half of the basal skull length, and the elliptical external naris, orbit, and a lower temporal fenestra oriented caudodorsally.
基金the Grand Project of the National Natural Science Foundation of China(Grant No.4983002)the National Natural Science Foundation of China(Grant No.49920026,40072006)+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20020145002) the keytask project of Science and Technology of Liaoning Province(Grant No.2001230001).
文摘A Iarge number of enantiornithine birds are discovered from the Early Cretaceous Jiufutang Formation in western Liaoning, China. They are all small-sized birds with a few small teeth. The enantiornithine bird from the Jiufutang Formation in the Shangheshou area, Chaoyang, Liaoning Province reported in this paper is the largest individual known in all enantiornithine birds of the Early Cretaceous. However, its teeth possess a feature of pseudoheterodont. Some different development stages of the new teeth substitute the earlier stages and the stages of development are preserved in this specimen. This development pattern is similar to that of Archaeopteryx and alligator but not dinosaur. A well-developed postorbital was also preserved in the skull, which was a diapsidian skull like that of Confuciusornis. Additionally, the distinctive preservation of its prefrontal distinguishes it from other enantiornithine birds of the Early Cretaceous.
基金This research was supported by gran ts from the National Natural Science Foundation of China(No.40302008)the Ministry of Science and Technology of China(No.2000077700)the National Science Foundation of the US.
文摘Three anurans (Callobatrachus sanyanensis, Liaobatrachus grabaui, Mesophryne beipiaoensis) and six urodeles (Laccotriton subsolanus, Liaoxitriton zhongjiani, Jeholotriton paradoxus, Sinerpeton fengshanensis, Chunerpeton tianyiensis, Liaoxitriton daohugouensis) are reported from the late Mesozoic tuff-interbedded lacustrine deposits (mostly of the Jehol Group) in northeastern China. They document the first discovery of Chinese Mesozoic lissamphibians, and their old geological age, superb preservation condition, and large taxoncmic diversity are unique compared with other findings worldwide. The anurans occupy a higher evolutionary position than typical Jurassic taxa, supporting a post-Late Jurassic age of the fossil horizons. The urodeles all have unicapitate ribs, suggesting an evolutionary grade at the cryptobranchoid level, and are advanced in osteological features over non-urodeles from the Middle and Upper Jurassic in England and Central Asia. Some urodeles (Jeholotriton and Chunerpeton) exhibit neotenic features, representing the earliest occurrence among such findings. Six fossil horizons are rscognized for the known Chinese Mesozoic anurans and urodeles: the Daohugou fossil bed, the Dabeigou Formation, the Lujiatun Bed, Jianshangou Bed and Dawangzhangzi Bed of the Yixian Formation, and the Jiufotang Formation. As implied from the osteological and phylogenetical studies, the geological age of these anurans and urodeles is the Early Cretaceous.
基金supported by the Ministry of Science and Technology of China(Grant No.G2000077700)the Na-tional Natural Science Foundation of China(Grant No.40232023)+1 种基金the Chinese Academy of Sciences(Grant No.RJZ2001-105)the Key Laboratory for Continental Dynamics of the Ministry of Education of China.
文摘Carbon isotope analysis of modern herbaceous plants in the Gyirong Basin (Tibet, China) indicates that although C3 plants are dominant, C4 plants rarely comprise of the vegetation in the area at 4000 m above sea level. The C4 plants discovered in the Gyirong Basin are Salsola nepalensis of Chenopodiaceae and Pennisetum flaccidum of Gramineae, affirming that C4 plants affected by high solar gain can be distributed at high altitude, which supports the opinion that some C4 plants can exist in areas of high elevation. Carbon isotope analysis of herbivore tooth enamel from the Gyirong Basin indicates that carbon isotopes of structural carbonate in biogenic apatite at high altitude still keep a stable enrichment relationship with those of plants in their diet. Carbon isotopes in tooth enamel are therefore an accurate proxy for vegetation ecotypes and should reflect climatic and environmental features.
文摘Hunter-gatherer populations in greater northeast Asia experienced dramatic range expansions during the early Upper Paleolithic (45—22 ka) and the late Upper Paleolithic (18—10 ka), both of which led to intensive occupations of cold desert environments including the Mongolian Gobi and northwest China. Range contractions under the cold, arid extremes of the Last Glacial Maximum (LGM, 22—18 ka) may have entailed widespread population extirpations. The high elevation Qinghai-Tibetan Plateau is significantly more extreme in both climate and environment than either the Gobi or the Siberian taiga forests, and provides an ideal setting to test fundamental models of human biogeog- raphy in the context of regional population fluctuations. The area is presently occupied primarily by nomadic pastoralists, but it is clear that these complex middle Holocene (<6 ka) economic adaptations were not a necessary prerequisite for successful colonization of the high elevation Plateau. Exploratory field-work in 2000—2001 has established that Upper Paleolithic hunter-gatherers were present on the Qinghai-Tibetan Plateau by at least 12 ka and possibly much earlier. A speculative model for the colonization process is developed and preliminary archaeological data in support of the model are presented.
文摘The Tianyuan Cave is the only human fos-sil-bearing site containing rich mammalian fossils found in the last decades near Zhoukoudian. Up to now more than 34 specimens of the human body have been recovered, and the mammalian fossils can be put into 29 species. Cervids domi-nate the fauna, and carnivores are very rare. Based on the primary examination, the human fossils can be attributed to the species Homo sapiens. All the mammalian fossils, except one between tooth of Crocuta belong to the species that still exist today. But some of them are the first records in fossil form north of the Yellow River, such as Arctonyx and Capri-cornis. Based on the mammalian fauna study, it seems that the Tianyuan Cave can be correlated with the Upper Cave. Sixty-three percent of the species of the mammalian fauna from the Tianyuan Cave are also present in the Upper Cave. The characters of the deposits also share some similarities between the Tianyuan Cave and the Upper Cave; both of them are mainly composed of breccia without cement. The dating using the U-series method on deer tooth samples in-dicates that the geological age of the new site is around 25 thousand years B.P. This is the first discovery of human sites outside the core area of the Peking Man Site at Zhoukoudian, which throws new light onto this world famous site complex.
文摘Rich paleoanthropological materials were unearthed in primary context from the Xinglongdong Cave in Fengjie County, Chongqing, South China, including a human tooth, numerous mammalian fossils, some stone artifacts and a Stegodon tusk exhibiting intentional engravings.Based on biostratigraphic data and uranium series dating,the cave was utilized as a human shelter about 120000-150000 years ago. It is the first time that an archaic Homo sapiens fossil has been unearthed from the Three Gorges Region. Engravings on the Stegodon tusk appear in groups,making up simple and abstract images. It is the earliest known engravings created by human beings; it exhibits great potential for the study of the origin of art and the development of ancient cultures in south China and bears important implications for the origin of modern humans in East Asia.
基金the Climbing Project of the Ministry of Science and Technology of China (Grant No. PD980002)
文摘The Yuanmou Basin of Yunnan Province is ahotspot for the research of early hominid evolution and its environmental background. During the implementation ofthe Program 揜esearch of the Origin and Evolution of Early Man and Its Environmental Background?from 1998 to 2001, a huge quantity of hominoid and mammal fossils were col-lected. The present report systematically describes an Eu-prox robustus sp. nov. identified during the recent laboratory work on the collected material. Euprox is a group of earliest cervids with true antlers. The new species is the third one of the genus discovered in China. Judged by its morphologiccharacteristics, the new species feed on juicy and tenderleaves of dicotyledon. It implies that the vegetation of itsepoch in the Yuanmou Basin is a kind of southern subtropi-cal evergreen forest and the climate is humid and temperate with evident seasonality. The latter is mostly influenced by the monsoon and secondly by the latitude.
基金This work was supported by the National Natural Science Foundation of China(Grant No.40121202)Special Funds for Major State Basic Research Projects of China(Grant No.TG2000077700)the Chinese Academy of Sciences(Grant No.KZCX3-SW-142).
基金the National Natural Science Foundation of China(Grant No.40272010)the Chinese Academy of Sciences(Grant No.KZCX3-SW-127)the Natural Sciences and Engineering Council of Canada