2.26" (5.74 cm) long, 1.81" (4.6 cm) tall, 1.02" (2.6 cm) tall Dromaeosaur? Vertebrae. Found in Custer County, Montana, from the Hell Creek formation, 66-70 million years old.

I believe this is a dromaeosaur tail vertebrae. But since no upper tail vertebrae have been described I can't be sure. It's theropod, and doesn't match tyrannosaur, ornithomimid or oviraptor. There is some gap fill.