It shows the characteristic hippopotamus-flange to the lower jaw, but has also a large descending process from the jugal bone of the zygomatic arch of the skull.
In the skull the tympanic bulla is hollow, the pterygoid fossa shallow and the zygomatic arch slender, with a rudimentary jugal bone.
In the skull the zygomatic arch is slender and the jugal bone small and not extending far forwards, being supported by the long zygomatic process of the maxilla, while the infra-orbital foramen is mostly large, and there are no post-orbital processes.
The front root of the zygomatic arch is nearly vertical, and placed so far back that it is above the second molar, while the orbit - a unique feature among rodents - is almost completely surrounded by bone.
The zygomatic arch is variously developed, and the position of the jugal is a character for grouping the families.
They are specially distinguished by the great development of the anterior half of the zygomatic arch of the skull, and by the presence in the boars of a horny protuberance of the skin in front of each eye, which overlies a tuberosity on the nasal bone; the molars are also small and simple, and the anterior premolars are generally shed at an early stage of life.