"Based upon the skull and the body as seen from this angle, I would say this is the front half of a canid, probably a dog. The “bird’s tail” is merely the spinal column extending out the midsection of a split body cavity. The “bird’s feet” are the front legs (probably with the actual feet taken off) of the canid. Nothing mysterious about this carcass, really."
With this said, it is most likely that the carcass belonged to dog, however the Iranian news article below thinks different.
"Is it a bird or something else? The creature, which was discovered near Meshginshahr in Iran is reportedly bipedal,
quickly decaying, and nothing like any of the other creatures ever discovered in the area - or anywhere else on Earth. Not only is the creature bipedal, it has massive teeth with fangs unlike anything we've seen flying through the air - at least not for several million years. Is this a survivor of the cretaceous period that somehow met its end recently in Iran? Or is this something completely different?
How could a creature that so clearly is very different from anything we've seen before survive near densely populated areas? And are there more of this species elsewhere in Iran? The creature, which was first reported by IRNA on Sunday had a long snout (or beak), feathers, and what appear to be two bird-like legs. But ornithologists looking into the case are saying those three things don't go together. Currently the incident is being investigated by the Iranian Environmental Protection Organization.
Cryptozoologists are equally vexed in most cased as they examine photographs of the bird's body. It is currently unknown what the composition of the creature's bones are, or how it could be held aloft if the head were made of the more dense heavy skull material of most land-based creatures.But the story doesn't end there. As officials continued their investigation, they found that the creature was recently alive. Villagers told stories of the creature living in a cave just outside the village where it would be seen walking about. Upon closer investigation of the area they found evidence that indeed something had recently been living there. But just what that is, they could not say.
You may recall coverage we did a year ago of the legendary Thunderbird of the western world. This creature not only had teeth, but tremendously powerful wings that would allow the incredibly large creature to stay aloft. This thunderbird was also said sometimes to have sharp fangs which it would use to rend the flesh of its victims during attacks.
The bird-creature, however, does not appear to have massive wings in this photo. Instead, it simply appears to be a roughly bird-shaped bipedal creature with an elongated snout and fangs. Whether the wings are part of the creature in the end will have to be determined by those studying the strange creature. But the investigation has run into a snag. Since they were sent to the area, the specimen has gone missing and there are rumors that one of the villagers might be hiding the creature for reasons that are not entirely clear. Some say this is evidence of a hoax, and to find the creature is to find the hoaxer who perpetrated it. But what would happen if the creature was discovered and found to be a genuine cryptozoological curiosity? And how does one go about hiding a decaying cryptid?"