Zygorhiza ("Yoke-Root") is an extinct genus of basilosaurid early whale known from the Late Eocene (Priabonian, 38–34 Ma) of Louisiana, Alabama, and Mississippi, United States, and the Bortonian (43–37 Ma on the New Zealand geologic time scale) to the late Eocene of New Zealand (43 to 33.9 million years ago).Specimens reported from Europe are considered Dorudontinae incertae sedis. Zygorhiza kochii is the state fossil of Mississippi. The mounted specimen in the Mississippi Museum of Natural Science in Jackson is commonly referred to as "Ziggy".