BIVALVE MOLLUSK PALEOECOLOGY: TROPHIC AND ENVIRONMENTAL RECONSTRUCTION FROM STABLE ISOTOPES, SCLEROCHRONOLOGY AND SHELL DAMAGE by Carlos Edgar Cintra Buenrostro ________________________ A Dissertation Submitted to the Faculty of the DEPARTMENT OF GEOSCIENCES In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 2006