13.1" Fossil Running Rhino (Hyracodon) Skull - South Dakota

This is a jaw dropping, 13.1" long skull of the running rhino, Hyracodon nebrascensis. It was collected from the the Brule Formation in South Dakota and would be approximately 30-34 million years old. This specimen includes the upper skull and mandible which are held together by the rock they were found in. The natural bone preserved well, though some sections of bone weren't recoverable due to compression, requiring restoration which I elaborate on below.

All of the molars and premolars on the maxilla and mandible are natural and haven't undergone any restoration, though there is a repaired crack between the root and crown of one of the molars. Three of the incisors on the maxilla are restored and six of the incisors on the mandible are either incomplete or restored.

Much of the nasal bone has been restored, with restoration continuing down the right side of the maxilla, stopping about 1-2" above the molars. Due to the natural compression and fragmentation of the bone, gap fill restoration will be found intermixed with natural bone throughout the upper skull just anterior to the nuchal crest. On the right side of the skull the zygomatic process of the temporal bone is restored, while the majority of the temporal process of the zygomatic bone is natural. Surprisingly, a good 95% of the nuchal crest is natural, only requiring some minor gap fill restoration between some of the fragmented bone. Overall this specimen is exceptionally well preserved.

About 5 to 10% of the natural rock has been replaced with false rock that fluoresces white under UV. This specimen is accompanied by a display stand.