Will mark

bird bones are not often found because:

birds did not exist until very recently
most bird species are now extinct
the bones are light and do not preserve well
scientists are not looking in the right places

the bones are light and do not preserve well

the united states has a federal government. the president is the head of the federal government of the united states. however, each state forms its government for administration purposes. the powers of the state governments are exercised within restricted state boundaries. and citizens participate in this government by voting.

buildings sir and respect