File:Teleoceras major (fossil barrel-bodied rhino) in fossiliferous volcanic tuff (Ash Hollow Formation, Miocene, 11.83 Ma; Ashfall Fossil Beds, Nebraska, USA) 1.jpg

English: Teleoceras major Hatcher, 1894 - fossil barrel-bodied rhinoceros in fossiliferous volcanic tuff in the Miocene of Nebraska, USA.

Volcanic tuff is a fine-grained, clastic-textured, extrusive igneous rock - basically a solidified volcanic ash deposit. Volcanic tuff can be well to poorly indurated / lithified. This exposure is at Nebraska's Ashfall Fossil Beds. The ash is derived from the Bruneau-Jarbidge Volcanic Field in southwestern Idaho's Snake River Plain. The wind-blown ash buried a vertebrate-rich biota at what was originally a Miocene waterhole.

The skull seen here is from a barrel-bodied rhino, Teleoceras major, which is a common species at Ashfall Fossil Beds.

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From on-site info.:

YOUNG ADULT MALE RHINO "Tusker"

Estimated Age: 8-9 years (wisdom teeth just coming in)

The highly polished tooth at the front of the jaw is a tusk. The large size of the tusk identifies this animal as a male. The thigh bone acros its face was probably pulled from the carcass of a neighboring rhino by a large predator.

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The most abundant large animal discovered in the volcanic ash bed is an extinct rhinoceros with a body shape similar to today's hippopotamus. Like hippos, barrel-bodied rhinos may have wallowed in the waterholes that dotted the ancient savannas of the Great Plains. Unlike modern-day rhinos, which are primarily solitary creatures, the Nebraska rhino probably was a social species that formed herds. By studying the age and sex of more than 100 skeletons from Ashfall, paleontologists concluded that Teleoceras males (with large tusks) may have defended "harems" of females (with small tusks) and their calves. Young adult male skeletons are remarkably rare in the ash bed, suggesting that "bachelor males" may have been excluded from the breeding herds and forced to live elsewhere.

Adult males were only about 3.5 feet tall at the shoulder but were over 10 feet long and 10 feet in circumference around the belly. Females measured 20% smaller.

[Teleoceras - ] the name means "perfect horn" and refers to the fact that both mle and female skulls have rough bumps near the end of their nasal bones, proving that they had a true horn in life.

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Classification: Animalia, Chordata, Vertebrata, Mammalia, Perissodactyla, Rhinocerotidae

Stratigraphy: Cap Rock Member, Ash Hollow Formation, Ogallala Group, Miocene, 11.83 Ma

Locality: Hubbard Rhino Barn, Ashfall Fossil Beds State Historical Park, northeastern Nebraska, USA

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Info. at: en.wikipedia.org/wiki/Teleoceras and

en.wikipedia.org/wiki/Ashfall_Fossil_Beds