The mollusc Watsonella crosbyi was studied on the basis of material from the lower Cambrian Dahai Member of the Zhujiaqing Formation in eastern Yunnan, China and the Pestrotsvet Formation of the Aldan River region in ...The mollusc Watsonella crosbyi was studied on the basis of material from the lower Cambrian Dahai Member of the Zhujiaqing Formation in eastern Yunnan, China and the Pestrotsvet Formation of the Aldan River region in the Siberian Platform. This fossil had been excessively described under different names in the literature, such as Heraultia varensalensis Cobboid, 1935, H. sibirica Missarzhevsky, 1974, Heraultipegma yunnanensis He and Yang, 1982, H. yannanese He and Yang,1982, Watsonella yunnanensis, W. crosbyi Grabau, 1900, etc. Taxonomic revision shows that other species are junior synonyms of W. crosbyi. Analysis of functional morphology implies that W. crosbyi may be rather a heicionelloid than a rostroconch since its univalved conch is untorted endogastric and lacks a rostrum and a true internal pegma. Replicas of the original microstrnctures preserved on the surfaces of phosphatic internal moulds confirm that the shell consists of two layers. The inner layer is lamello-fibrillar, and the outer layer is spherulitic prismatic. The widespread geographical occurrences in both siliciclastic and carbonate rocks of the late Terreneuvian indicate that W. crosbyi is an important index fossil for global correlations and subdivision of the Cambrian Series I （Terreneuvian）.The first appearance datum （FAD） of W. crosbyi is suggested to be a potential GSSP （Global Boundary Stratotype Section and Point） candidate marker for defining the base of the Cambrian Stage 2.展开更多
Yanjiahella gen. nov., a distinctive fossil taxon from the Early Cambrian Yanjiahe Biota in Yichang, Hubei Province, is characterized by： 1） an overall body plan composed of a stalk and a calyx （also arms in some s...Yanjiahella gen. nov., a distinctive fossil taxon from the Early Cambrian Yanjiahe Biota in Yichang, Hubei Province, is characterized by： 1） an overall body plan composed of a stalk and a calyx （also arms in some species）; 2） a stalk with closely spaced, transverse wrinkles and a medial, longitudinal ridge; and 3） a calyx preserved with three-dimensional radiating striations, as well as a probable madreporite in some specimens. Three species that can be assigned to this genus, which are Y. ancarpa sp. nov., Y. monocarpa sp. nov., and Y. biscarpa sp. nov. Yanjiahella is comparable to certain echinoderm taxa in terms of morphology and some biological structures, which might indicate the early evolution and diversification of ancestral echinoderm lineages from the early Early Cambrian Yangtze Platform. The discovery of putative echinoderms in the Yanjiahe Biota provides significant clues about the origination and evolution of the deuterostome phylum Echinodermata.展开更多
基金supported by the Chinese Academy of Sciences (KZCX3-EW-115)the Ministry of Science and Technology of China (2006FY120300-3)the National Natural Science Foundation of China, and National Science and Technology Major Project (2008ZX05008-001-001)
文摘The mollusc Watsonella crosbyi was studied on the basis of material from the lower Cambrian Dahai Member of the Zhujiaqing Formation in eastern Yunnan, China and the Pestrotsvet Formation of the Aldan River region in the Siberian Platform. This fossil had been excessively described under different names in the literature, such as Heraultia varensalensis Cobboid, 1935, H. sibirica Missarzhevsky, 1974, Heraultipegma yunnanensis He and Yang, 1982, H. yannanese He and Yang,1982, Watsonella yunnanensis, W. crosbyi Grabau, 1900, etc. Taxonomic revision shows that other species are junior synonyms of W. crosbyi. Analysis of functional morphology implies that W. crosbyi may be rather a heicionelloid than a rostroconch since its univalved conch is untorted endogastric and lacks a rostrum and a true internal pegma. Replicas of the original microstrnctures preserved on the surfaces of phosphatic internal moulds confirm that the shell consists of two layers. The inner layer is lamello-fibrillar, and the outer layer is spherulitic prismatic. The widespread geographical occurrences in both siliciclastic and carbonate rocks of the late Terreneuvian indicate that W. crosbyi is an important index fossil for global correlations and subdivision of the Cambrian Series I （Terreneuvian）.The first appearance datum （FAD） of W. crosbyi is suggested to be a potential GSSP （Global Boundary Stratotype Section and Point） candidate marker for defining the base of the Cambrian Stage 2.
基金funded by National Basic Research Program of China(Grant No.40902007)the Special Fund for Basic Scientific Research of Central Colleges, Chang'an University,China(Grant Nos CHD2011TD005, CHD2011TD020,CHD2010JC074,CHD2009JC0018)+1 种基金the China Postdoctoral Science Foundation(Grant No. 20100471020)the Doctoral Fund of Ministry of Education of China(Grant No.20100205110003)
文摘Yanjiahella gen. nov., a distinctive fossil taxon from the Early Cambrian Yanjiahe Biota in Yichang, Hubei Province, is characterized by： 1） an overall body plan composed of a stalk and a calyx （also arms in some species）; 2） a stalk with closely spaced, transverse wrinkles and a medial, longitudinal ridge; and 3） a calyx preserved with three-dimensional radiating striations, as well as a probable madreporite in some specimens. Three species that can be assigned to this genus, which are Y. ancarpa sp. nov., Y. monocarpa sp. nov., and Y. biscarpa sp. nov. Yanjiahella is comparable to certain echinoderm taxa in terms of morphology and some biological structures, which might indicate the early evolution and diversification of ancestral echinoderm lineages from the early Early Cambrian Yangtze Platform. The discovery of putative echinoderms in the Yanjiahe Biota provides significant clues about the origination and evolution of the deuterostome phylum Echinodermata.
