This Fossil Friday we have the dental plate of a cownose ray (genus Rhinoptera). This fossil is from the Gatún Formation and is late Miocene in age. Today, modern members of this genus (see photo below) can be found swimming in the shallows of the Pacific Ocean. A ray that possessed this dental plate would have used it to prey on invertebrates by sucking them into its mouth and crushing them. Skates and rays are known as batoids and, like sharks, are cartilaginous fish (chondricthyans).
To learn more about this specimen, check out the Fossils of Panama page on it here.