looks like a pet dog to me, there may be other bones in there from another animal depending on what it was being fed, or not. . .

That bone youre calling a flipper is the scapula, as was pointed out, it's the shoulder of the dog. . .

By dog i'm not saying it's barny or rover, i'm using the term dog loosely, in fact it may be an exotic species so it may be hard to tell. . . get more information and take it to your local vet, he/she might know about this animal . . .