Titanotheres are large, thick-skinned quadrupeds.
As the encyclopedia says, titanotheres were extinct relatives of the rhinocerous and lived during the Oligocene. They lived in areas that are currently in the United States. They are also known as Brontotheres.
Unlike modern rhinos, titanotheres had a forked horn.
Extinct rhinos include a variety of forms, the most
spectacular being _Baluchitherium_ from the Oligocene of
Asia, which is the largest known land mammal. Its body, 18
feet high at the shoulder and carried on massive limbs,
allowed the 4-foot-long head to browse on the higher branches
of trees. Though not as enormous, the titanotheres of the
early Tertiary were also large perissodactyls, _Brontotherium_
of the Oligocene being 8 feet high at the shoulder.