This image is of a Atocetus fuchsii dolphin fin fossil model on display at Mace Brown Museum of Natural History (August 2017). It dates to the Miocene Epoch (about 12 million years ago), Neogene Period. The fossil was found in the Sarmatian Marl, Chinteni Village, Cluj-Napoca, Romania.
Learn more at their blog: http://blogs.cofc.edu/macebrownmuseum/