It seems to be the distal end of a bovid metacarpal, which could be either cow or bison. Difficult to tell them apart without close examination of the complete bone, but it looks to be within the size range for cattle, but small for bison unless from a youngster.
It seems also to have seen some rodent gnawing (usually squirrel or rat). I would say cow and cut with a modern saw.
Yep beat me to it, my first thought was a dog treat, to my knowledge there’s nothing worth buying and cooking on that part of the animal, so maybe they cut them off and turn a little profit selling them as something for a dog to chew on… not that a dog made those marks, that’s definitely a rodent. Maybe Rex carried it outside and lost interest and a rat or squirrel found it.