Wyoming bone fossil

This is a fossilized bone fragment found in Sheridan County, WY, summer of 1999. The thumbnail graphics are linked to larger versions of the photos.

geological map This is a portion of a geologic map[1] of the area. The point of the red V is approximately where the rock was uncovered, in the Jurassic Sundance formation.
view from Sand Turn This is a view of the surrounding area from Sand Turn in the Big Horn Mountains. The red V points to where the rock was probably uncovered. The view is towards east.
view of fence The rancher was using a cat to prepare for building this fence, and removed large pieces of a limestone ledge. The debris was skidded into a ravine for erosion control.
front view of rock Later, he found the fossil piece lying in the roadbed. This is a front view of the rock. The coin on the rock is a USA Sacajawea dollar.
close up of front Close up view of the front.
another front close up Another close up view of the front of the rock.
back view of the rock Back view of the rock.
close up of back Close up view of the back.
another fossil Most of the debris in the ravine was covered, with dirt and old barbed wire. This fossil fragment was visible. It is about an inch wide. The rock is wet.
rhomaleosaurus Dr. David Martill of the University of Portsmouth has suggested that the original fossil was a humerus with radius and ulna, possibly an early Jurassic pliosauru such as Rhomaleosaurus, which would be the first such found in the United States.

[1] Langenheim, Reinbold and Tissue, in the Wyoming Geological Association Guidebook, Twenty-Eighth Annual Field Conference--1976, pp.97-105.