Copepod-infested Bathonian (Middle Jurassic) echinoids from northern France
Authors
Urszula Radwanska
Institute of Geology, University of Warsaw, Al. Żwirki i Wigury 93; PL-02-089 Warszawa
Eric Poirot
240 Grande Rue, Cedex 307, F-54113 Moutrot
Keywords:
Parasitic cysts, Copepod crustaceans, Echinoids, Middle Jurassic, Bathonian, France
Abstract
New examples of Bathonian (Middle Jurassic) parasitic exocysts on acrosaleniid echinoid tests are recorded from northern France. These exocysts can be attributed to the life activity of copepod crustaceans and are considered to have been formed as a result of copepod larval settlement in these echinoids by way of the gonopores. Sexual dimorphism is recognised in copepod-infested Acrosalenia spinosa L. Agassiz, 1840, on the basis of size and position of gonopores, those in females being larger and wider apart, those in males smaller and situated subcentrally. The previous stratigraphic range of copepod cysts of this type (i.e., Middle Oxfordian to Middle Kimmeridgian) can now be extended down to the base of the Bathonian (convergens Subzone).
