Black bedded, nodular, and lenticular chert and silicified parts of stromatolites from the approximately 1 400 - 1 600 million year-old Gaoyuzhuang Formation, North China, contain remark-ably well prep served microflo...Black bedded, nodular, and lenticular chert and silicified parts of stromatolites from the approximately 1 400 - 1 600 million year-old Gaoyuzhuang Formation, North China, contain remark-ably well prep served microflora composed of diverse prokaryotic and possible eukaryotic microbes. Macroscopic algae have also been found. This Formation provides important paleobiological information from which to assess status of Mesoproterozoic life, and to evaluate paleoenvironmental conditions and pre-Phanerozoic biostratigraphy. The Gaoyuzhuang Formation has yielded over 100 taxa described by over 10 investigators. Most of the microbial taxa can be divided into three different assemblages according to their paleobiological and paleoenvironmental characteristics. I. The oscillatoriacean/chroococcacean assemblage which occurs in the first member of the Formation and this is interpreted to represent an assemblage from shallow water mat-building and mat-dwelling taxa with some possible planktonic taxa; 2. the nostocacean assemblage found only in the second member, and includes benthic mat-building or mat-dwelling taxa; and 3. the chroococcacean assemblage of the fourth member, which represents intertidal to supratidal mat-building and allochthonous taxa. Proterozoic microfossils found in chert, especially cyanobacteria, are possibly more valuable as paleoenvironmental indicators than as chronostratigraphic tools because of their morphological conservation, although trends in diversity appear to exist for cyanobacteria in the Proterozoic. The general characteristics of Gaoyuzhuang microfossils, and the fact that most nostocacean chains occur and are. preserved with the chain perpendicular to bedding indicate that: (1) the individual size of Gaoyuzhuang microfossils are part of a general trend of increase with time; (2) Gaoyuzhuang deposits are possibly in a fresh water environment and the rate of sedimentation might be equal to or less than the microbial growth rate; (3) the sedimentary model of Gaoyuzhuang might be from intertidal to subtidal or deep sea, and then to intertidal or supratidal; and (4) the eukaryotic organisms had densely occurred when Gaoyuzhuang Formation deposited.展开更多
Established in 1989, the Open Laboratory ofPalaeobiology & Stratigraphy is a department-spon-sored experimental entity and the only one of its kindin China. At present, it has become a research basefor disciplinar...Established in 1989, the Open Laboratory ofPalaeobiology & Stratigraphy is a department-spon-sored experimental entity and the only one of its kindin China. At present, it has become a research basefor disciplinary studies of Palaeobiology &Stratigraphy. It is noted for its innovative work incarrying out such projects as "Early life evolution &Cambrian biota explosion," "Global stratotypes of theOrdovician series and stage boundaries," "展开更多
The anurognathids are an enigmatic and distinctive clade of small,non-pterodactyloid pterosaurs with an unusual combination of anatomical traits in the head,neck,wings and tail.They are known from very limited remains...The anurognathids are an enigmatic and distinctive clade of small,non-pterodactyloid pterosaurs with an unusual combination of anatomical traits in the head,neck,wings and tail.They are known from very limited remains and few have been described in detail,and as a result,much of their biology remains uncertain.This is despite their importance as potentially one of the earliest branches of pterosaur evolution or even lying close to the origins of pterodactyloids.This review covers the taxonomy and palaeoecology of the anurognathids,which remain an interesting branch of pterosaurian evolution.展开更多
文摘Black bedded, nodular, and lenticular chert and silicified parts of stromatolites from the approximately 1 400 - 1 600 million year-old Gaoyuzhuang Formation, North China, contain remark-ably well prep served microflora composed of diverse prokaryotic and possible eukaryotic microbes. Macroscopic algae have also been found. This Formation provides important paleobiological information from which to assess status of Mesoproterozoic life, and to evaluate paleoenvironmental conditions and pre-Phanerozoic biostratigraphy. The Gaoyuzhuang Formation has yielded over 100 taxa described by over 10 investigators. Most of the microbial taxa can be divided into three different assemblages according to their paleobiological and paleoenvironmental characteristics. I. The oscillatoriacean/chroococcacean assemblage which occurs in the first member of the Formation and this is interpreted to represent an assemblage from shallow water mat-building and mat-dwelling taxa with some possible planktonic taxa; 2. the nostocacean assemblage found only in the second member, and includes benthic mat-building or mat-dwelling taxa; and 3. the chroococcacean assemblage of the fourth member, which represents intertidal to supratidal mat-building and allochthonous taxa. Proterozoic microfossils found in chert, especially cyanobacteria, are possibly more valuable as paleoenvironmental indicators than as chronostratigraphic tools because of their morphological conservation, although trends in diversity appear to exist for cyanobacteria in the Proterozoic. The general characteristics of Gaoyuzhuang microfossils, and the fact that most nostocacean chains occur and are. preserved with the chain perpendicular to bedding indicate that: (1) the individual size of Gaoyuzhuang microfossils are part of a general trend of increase with time; (2) Gaoyuzhuang deposits are possibly in a fresh water environment and the rate of sedimentation might be equal to or less than the microbial growth rate; (3) the sedimentary model of Gaoyuzhuang might be from intertidal to subtidal or deep sea, and then to intertidal or supratidal; and (4) the eukaryotic organisms had densely occurred when Gaoyuzhuang Formation deposited.
文摘Established in 1989, the Open Laboratory ofPalaeobiology & Stratigraphy is a department-spon-sored experimental entity and the only one of its kindin China. At present, it has become a research basefor disciplinary studies of Palaeobiology &Stratigraphy. It is noted for its innovative work incarrying out such projects as "Early life evolution &Cambrian biota explosion," "Global stratotypes of theOrdovician series and stage boundaries," "
文摘The anurognathids are an enigmatic and distinctive clade of small,non-pterodactyloid pterosaurs with an unusual combination of anatomical traits in the head,neck,wings and tail.They are known from very limited remains and few have been described in detail,and as a result,much of their biology remains uncertain.This is despite their importance as potentially one of the earliest branches of pterosaur evolution or even lying close to the origins of pterodactyloids.This review covers the taxonomy and palaeoecology of the anurognathids,which remain an interesting branch of pterosaurian evolution.
