Wow! I missed this in the SVP abstract book this year. Lungfish toothplates are a common fossil from the Chinle Formation, but I've never seen any specimen even come close to the size of this one from the Cretaceous of North America. Unfortunately, the provenance is not exactly known; however, the specimen is 117mm wide and would have come from an animal with an estimated body length of 4 meters. That is one big dipnoan, a full two meters larger than living forms today. You can read more about this here. The suggested diet is turtles, but there are plenty of large freshwater invertebrates during the Cretaceous as well.