Xiphiacetus is an extinct genus of cetacean known from the Miocene (early Burdigalian to late Tortonian, 20.43 to 7.246 million years ago of Europe and the U.S. East Coast. described Priscodelphinus cristatus based on partial and poorly preserved skulls with extremely long and narrow rostra with a huge number of densely packed teeth. He estimated the rostrum of a large specimen to be 90 cm (35 in) long and the cranium to be 20 cm (7.9 in) long and slightly wider. He also found a series of well-preserved cervicals and a few of the anterior-most thoracics.