Are known? there's only 3 cases of bite marks on dinosaur bones attributed to Deinosuchus, two on hadrosaurid remains, probably Kritosaurus and one in a small-ish theropod. Predation is not certain, however there's lots of turtle shells indicating that Deinosuchus frequently preyed on marine turtles.
There's no evidence of Sarcosuchus preying on any dinosaur, Sereno et al. conclusion basically says it could because its snout was more robust than in the gharial and that's it, when in fact its rostral proportion indicates that its snout was no wider than those of slender-snouted and freshwater crocodiles, that its snout was not only uniformly very shallow across all of its length (from 12 to 10cm) as it was its dentary but that the proportional size (most around 3 to 4cm, just 4 up to 7cm long), arrangement (equal to those of the much slender snouted Terminonaris and similar to that of Tomistoma) and number of its teeth (30 in the maxilla, much more than even the gharial) are more consistent with a mostly piscivorous diet, though given its size, full grown adults could have preyed and huge fish and small dinosaurs but there's nothing on Sarcosuchus anatomy indicating a macrophagus diet.