Document Detail


Exceptionally preserved crustaceans from western Canada reveal a cryptic Cambrian radiation.
MedLine Citation:
PMID:  22307616     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The early history of crustaceans is obscured by strong biases in fossil preservation, but a previously overlooked taphonomic mode yields important complementary insights. Here we describe diverse crustacean appendages of Middle and Late Cambrian age from shallow-marine mudstones of the Deadwood Formation in western Canada. The fossils occur as flattened and fragmentary carbonaceous cuticles but provide a suite of phylogenetic and ecological data by virtue of their detailed preservation. In addition to an unprecedented range of complex, largely articulated filtering limbs, we identify at least four distinct types of mandible. Together, these fossils provide the earliest evidence for crown-group branchiopods and total-group copepods and ostracods, extending the respective ranges of these clades back from the Devonian, Pennsylvanian, and Ordovician. Detailed similarities with living forms demonstrate the early origins and subsequent conservation of various complex food-handling adaptations, including a directional mandibular asymmetry that has persisted through half a billion years of evolution. At the same time, the Deadwood fossils indicate profound secular changes in crustacean ecology in terms of body size and environmental distribution. The earliest radiation of crustaceans is largely cryptic in the fossil record, but "small carbonaceous fossils" reveal organisms of surprisingly modern aspect operating in an unfamiliar biosphere.
Authors:
Thomas H P Harvey; Maria I Vélez; Nicholas J Butterfield
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-01-17
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  109     ISSN:  1091-6490     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-02-06     Completed Date:  2012-03-30     Revised Date:  2013-06-26    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1589-94     Citation Subset:  IM    
Affiliation:
Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, United Kingdom.
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MeSH Terms
Descriptor/Qualifier:
Animals
Canada
Crustacea*
Fossils*
Mandible / anatomy & histology
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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