a) Lately there has been a movement in the realm of archaeology to go back and rethink "arrow-head" marks and other signs of human involvement. These same marks can appear through non-human activities such as teeth marks, damage during decay, etc. Produce that arrow head and prove that it lay in the same strata as the "dinosaur" or STFU.
b) Are you sure it was a dinosaur? Not all large bones are, you know. And if you are from the states, which I suspect you are, please be aware that in prehistory in N. America there was such a thing as "megafauna".
c) You wanna know why the excavation went so fast? The developers are required to hire arachaeologists during the surveys of a site and required to call them if they find anything, but they aren't required to give them adequete time to excavate. If the archaeologist (or paleotologist, in this case) had tried to take his good sweet time to thouroughly excavate he would have gotten hell from the developers and community. That's just how it goes, it sucks.