Interesting! At a first glance, kinda recalls me of a derived Maniraptoriformes neural arch (Oviraptorosaurian? Alvarezsauroid?), but need a more thorough double check, maybe with some more views.
For me it's difficult to give a clear systematic solution based exclusively on these photos, but I think also that it's a vertebra fragment. But the discovery it's exiting, try to find additional material, it worth a lot.
Thanks for all suggestions. I will compare it with other neural arches of derived theropods. It woud be great to find additional material but for now this fossil remain was found isolated on surface in a badly exposed outcrop