An Early Cambrian tunicate from China

Like the Burgess Shales of Canada, the Chengjiang Lagerstätte from the Lower Cambrian of China is renowned for the detailed preservation as fossils of delicate, soft-bodied creatures, providing an insight into the Cambrian explosion. The fossils of possible hemichordate chordates and vertebrates have attracted particular attention. Tunicates, or urochordates, comprise the most basal chordate clade, and details of their evolution could be important in understanding the sequence of character acquisition that led to the emergence of chordates and vertebrates. However, definitive fossils of tunicates from the Cambrian are scarce or debatable. Here we report a probable tunicate Cheungkongella ancestralis from the Chengjiang fauna. It resembles the extant ascidian tunicate genus Styela whose morphology could be useful in understanding the origin of the vertebrates.

[1]  Zhang Aiyun.  FOSSIL APPENDICULARIANS IN THE EARLY CAMBRIAN , 1987 .

[2]  H. Wada.  Details of the evolutionary history of invertebrates to vertebrates as deduced from sequence 18S rRNA , 1994 .

[3]  M. Levine,et al.  Ascidian embryogenesis and the origins of the chordate body plan. , 1998, Current opinion in genetics & development.

[4]  S. Morris,et al.  A Pikaia-like chordate from the Lower Cambrian of China , 1996, Nature.

[5]  N. Satoh,et al.  Developmental Biology of Ascidians , 1995 .

[6]  C. Nielsen.  Animal Evolution: Interrelationships of the Living Phyla , 1995 .

[7]  D. Shu,et al.  Anatomy and systematic affinities of the Lower Cambrian bivalved arthropod Isoxys auritus , 1995 .

[8]  H. Wada,et al.  Details of the evolutionary history from invertebrates to vertebrates, as deduced from the sequences of 18S rDNA. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[9]  Douglas H. Erwin,et al.  The Fossils of the Burgess Shale , 1994 .

[10]  D. Shu,et al.  Reinterpretation of Yunnanozoon as the earliest known hemichordate , 1996, Nature.

[11]  G. Edgecombe,et al.  A possible Early Cambrian chordate , 1995, Nature.

[12]  N. Berrill.  The origin of vertebrates , 1955 .

[13]  N. Satoh,et al.  Ascidian Homologs of Mammalian Thyroid Transcription Factor-1 Gene Are Expressed in the Endostyle , 1999 .

[14]  H. Wada.  Evolutionary history of free-swimming and sessile lifestyles in urochordates as deduced from 18S rDNA molecular phylogeny. , 1998, Molecular biology and evolution.

[15]  M. Jollie.  What are the ‘Calcichordata’? and the larger question of the origin of Chordates , 1982 .

[16]  W. Garstang.  Memoirs: The Morphology of the Tunicata, and its Bearings on the Phylogeny of the Chordata , 1928 .

[17]  B. Swalla,et al.  Evolution of the chordate body plan: new insights from phylogenetic analyses of deuterostome phyla. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[18]  S. Morris,et al.  Lower Cambrian vertebrates from south China , 1999, Nature.

[19]  Jian Han,et al.  New sites of Chengjiang fossils: crucial windows on the Cambrian explosion , 2001, Journal of the Geological Society.

[20]  X. Hou,et al.  Arthropods of the Lower Cambrian Chengjiang fauna, southwest China , 1997, Fossils and Strata.

[21]  K. Müller.  Palaeobotryllus from the Upper Cambrian of Nevada — a probable ascidian , 1977 .

[22]  S. Morris,et al.  A pipiscid-like fossil from the Lower Cambrian of south China , 1999, Nature.

[23]  A. Romer.  The Vertebrate Story , 1959 .

[24]  B. Swalla,et al.  Urochordates are monophyletic within the deuterostomes. , 2000, Systematic biology.