Late Cretaceous

Lance Formation, Krejci Ranch

Niobrara County, WY, USA

Unusual 0.25 inch vertebra

Reptile.

This might be a lizard vertebra.  Somebody willing to do some research could figure out what it is.

Triceratops and Tyrannosaurus remains have also been found in the Lance Formation which represents the last few million years of the Cretaceous Period.  Their vertebrae are much larger.