Morphology and function in the Cambrian Burgess Shale megacheiran arthropod Leanchoilia superlata and the application of a descriptive matrix
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
BMC Evolutionary Biology 2012, 12:162 doi:10.1186/1471-2148-12-162Published: 30 August 2012
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.
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.
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).