What is "mylagaulidae"

The Mylagaulidae or mylagaulids are a prehistoric family of sciuromorph rodents. They are known from the Neogene of North America and China. The oldest member is the Late Oligocene Trilaccogaulus montanensis from living some 29 million years ago (Mya), and the youngest was Ceratogaulus hatcheri—formerly in Epigaulus—which was found barely into the Pliocene, some 5 Mya.