0.87" (2.21 cm) Ceratosaurus or Allosaurus tooth from the Morrison Formation of Moffat County, Colorado. 149 million years old. This tooth is a little off for Allosaurus. It's symmetrical, pretty thin, the serrations are a bit of a different size from distal to mesial. However, due to how close some Allosaurus and Ceratosaurus teeth can be I cannot say for certain.