Wow that is a weird one! Sorry for the delayed response. I am in the field, busy busy, and had difficulty with my password and resetting my password to get onto the site. My first reaction is that it is not a dinosaur and not an ungual. I suspect that it might be a worn vertebra missing the neural arch. Not sure on species yet, but its size and shape are not consistant with a young hadrosaur ungual. Lookis like a reptilian centra except for the “anterior” end. I have a couple days off around the 4th and can look into it further then. Love a good mystery!!!