roscore
roslaunch marco_description upload_marco.launch
Also:
rosparam set /robot_description "`rosrun xacro xacro.py robot.urdf`"
rosrun joint_state_publisher joint_state_publisher _use_gui:=true
rosrun robot_state_publisher robot_state_publisher
rosrun rviz rviz
Relaunch the robot description and robot state publisher to see new URDF.