Résumé
The shallow marine deposits of the Lutetian of Saudi Arabia (Dammam Formation) yield common and diverse marine biota, including abundant isolated fish teeth. Several taxa of ray-finned fishes and elasmobranchs, dominated by sand tiger sharks, tiger sharks, and hammerhead sharks were used for oxygen isotope analysis of tooth apatite (delta (super 18) O (sub p) ) to estimate seawater temperatures in the tropical Neo-Tethys during the Lutetian. Petrographic observations including cathodoluminescence and rare earth element (REE) concentrations were used to assess a possible diagenetic overprint. REEs and cathodoluminescence data suggest that dentine tissue is systematically altered by diagenesis, whereas enamel(oid) is well preserved and can be used for palaeoenvironmental reconstructions. delta (super 18) O (sub p) in shark tooth enameloid varies between 18.0 and 21.9 per mille (average value of 19.4 + or - 0.8 per mille, n = 31), corresponding to an average calculated temperature of 27.9 + or - 3.4 degrees C using delta (super 18) O (sub water) of -0.5 per mille V-SMOW. Ray-finned fish delta (super 18) O (sub p) values range from 19.4 per mille to 20.9 per mille (average 20.0 + or - 0.4 per mille, n = 31), with an average calculated temperature of 27.3 + or - 2.1 degrees C using delta (super 18) O (sub water) of 0 per mille V-SMOW. The higher delta (super 18) O (sub p) values of ray-finned fish, however, are interpreted to be influenced by higher evaporation rates nearshore. Calculated temperatures from shark teeth are consistent with modeled Eocene sea surface temperatures, suggesting that shark tooth delta (super 18) O can be a useful proxy for paleoenvironmental reconstructions at basin scale.