Open Access Research article

Morphology and function in the Cambrian Burgess Shale megacheiran arthropod Leanchoilia superlata and the application of a descriptive matrix

Joachim T Haug1*, Derek EG Briggs23 and Carolin Haug1

Author Affiliations

1 Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, University of Greifswald, Soldmannstr. 23, 17487, Greifswald, Germany

2 Department of Geology and Geophysics, Yale University, PO Box 208109, New Haven, CT, 06511, USA

3 Yale Peabody Museum of Natural History, Yale University, New Haven, CT, 06520, USA

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BMC Evolutionary Biology 2012, 12:162  doi:10.1186/1471-2148-12-162

Published: 30 August 2012

Abstract

Background

Leanchoilia superlata is one of the best known arthropods from the middle Cambrian Burgess Shale of British Columbia. Here we re-describe the morphology of L. superlata and discuss its possible autecology. The re-description follows a standardized scheme, the descriptive matrix approach, designed to provide a template for descriptions of other megacheiran species.

Results

Our findings differ in several respects from previous interpretations. Examples include a more slender body; a possible hypostome; a small specialised second appendage, bringing the number of pairs of head appendages to four; a further sub-division of the great appendage, making it more similar to that of other megacheirans; and a complex joint of the exopod reflecting the arthropod’s swimming capabilities.

Conclusions

Different aspects of the morphology, for example, the morphology of the great appendage and the presence of a basipod with strong median armature on the biramous appendages indicate that L. superlata was an active and agile necto-benthic predator (not a scavenger or deposit feeder as previously interpreted).

Keywords:
Megacheira; Great-appendage arthropods; Chelicerata sensu lato; Descriptive matrix; Active predator